Now Including International Topics · standpoint of pest, diseases, and soil fertility. The main...

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Now Including International T Now Including International T Now Including International T Now Including International T Now Including International Topics opics opics opics opics 2005 Number 1 2005 Number 1 2005 Number 1 2005 Number 1 2005 Number 1 I N T T T T THIS HIS HIS HIS HIS I I I I I SSUE SSUE SSUE SSUE SSUE Fertilization for Cotton Rotations Managing High Yield Canola Cultivars What Is Sustainable Agriculture and How Do We Do It? ... and much more Introducing: Introducing: Introducing: Introducing: Introducing: Be Y Be Y Be Y Be Y Be Your Own our Own our Own our Own our Own Cotton Doctor Cotton Doctor Cotton Doctor Cotton Doctor Cotton Doctor See page 21 See page 21 See page 21 See page 21 See page 21

Transcript of Now Including International Topics · standpoint of pest, diseases, and soil fertility. The main...

Page 1: Now Including International Topics · standpoint of pest, diseases, and soil fertility. The main rotation crop in cotton cropping in the Southern High Plains is sorghum. Surprisingly,

Now Including International TNow Including International TNow Including International TNow Including International TNow Including International Topicsopicsopicsopicsopics2005 Number 12005 Number 12005 Number 12005 Number 12005 Number 1

IIIIINNNNN T T T T THISHISHISHISHIS I I I I ISSUESSUESSUESSUESSUE

• Fertilization for CottonRotations

• Managing High YieldCanola Cultivars

• What Is SustainableAgriculture and HowDo We Do It?... and much more

Introducing:Introducing:Introducing:Introducing:Introducing:Be YBe YBe YBe YBe Your Ownour Ownour Ownour Ownour OwnCotton DoctorCotton DoctorCotton DoctorCotton DoctorCotton DoctorSee page 21See page 21See page 21See page 21See page 21

61885_01.p65 2/3/2005, 10:12 AM1

Page 2: Now Including International Topics · standpoint of pest, diseases, and soil fertility. The main rotation crop in cotton cropping in the Southern High Plains is sorghum. Surprisingly,

Vol. LXXXIX (89) 2005, No. 1

Our Cover: Introducing �Be Your Own Cotton Doctor�Cover Design: Todd Scott/Kathy Hefner

Editor: Donald L. ArmstrongAssistant Editor: Katherine P. GriffinCirculation Manager: Carol MeesDesign: Kathy Hefner

Potash & Phosphate Institute (PPI)W.J. Doyle, Chairman of the Board

PotashCorpF.W. Corrigan, Vice Chairman of the Board

MosaicW.J. Whitacre, Chairman, Finance Committee

Simplot

HEADQUARTERS: NORCROSS, GEORGIA, U.S.A.D.W. Dibb, PresidentT.L. Roberts, Senior Vice President, PPI/PPICC.V. Holcomb, Assistant TreasurerS.J. Couch, IT ManagerB. Rose, Statistics/Accounting

NORTH AMERICAN PROGRAMS-Brookings, South DakotaP.E. Fixen, Senior Vice President, North American Program

Coordinator, and Director of ResearchP. Pates, Secretary

REGIONAL DIRECTORS-North AmericaT.W. Bruulsema, Guelph, OntarioA.M. Johnston, Saskatoon, SaskatchewanR.L. Mikkelsen, Davis, CaliforniaT.S. Murrell, Woodbury, MinnesotaC.S. Snyder, Conway, ArkansasW.M. Stewart, San Antonio, Texas

INTERNATIONAL PROGRAMSPotash & Phosphate Institute of Canada (PPIC)T.L. Roberts, Senior Vice President, PPI/PPIC

International Program CoordinatorA.M. Johnston, President, PPIC, Saskatoon, SaskatchewanL.M. Doell, Corporate Secretary, PPIC, and

Administrative Assistant, Saskatoon, SaskatchewanG. Sulewski, Agronomist, Saskatoon, Saskatchewan

INTERNATIONAL PROGRAM LOCATIONSBrazil T. Yamada, POTAFOS, PiracicabaChina Ji-yun Jin, Beijing

Ping He, BeijingShutian Li, BeijingFang Chen, WuhanShihua Tu, Chengdu

India K.N. Tiwari, Gurgaon, HaryanaT.N. Rao, Hyderabad, Andhra PradeshK. Majumdar, Calcutta (Kolkata), West Bengal

Northern Latin America J. Espinosa, Quito, EcuadorLatin America-Southern Cone F.O. Garcia, Buenos Aires, ArgentinaSoutheast Asia C. Witt, Singapore

Foundation for Agronomic Research (FAR), Monticello, IllinoisH.F. Reetz, Jr., President

BETTER CROPS WITH PLANT FOOD(ISSN:0006-0089) is published quarterly by the Potash & PhosphateInstitute (PPI). Periodicals postage paid at Norcross, GA, and atadditional mailing offices (USPS 012-713). Subscription free onrequest to qualified individuals; others $8.00 per year or $2.00 perissue. POSTMASTER: Send address changes to Better Crops with PlantFood, 655 Engineering Drive, Suite 110, Norcross, GA 30092-2837.Phone (770) 447-0335; fax (770) 448-0439. www.ppi-ppic.org.Copyright 2005 by Potash & Phosphate Institute.

The Government of Saskatchewan helps make the InternationalSection of this publication possible through its resource tax funding.We thank them for their support of this important educationalproject.

Members: Agrium Inc. • Intrepid Mining, LLC • Mosaic • PotashCorp • Simplot • Yara International

C O N T E N T SC O N T E N T SC O N T E N T SC O N T E N T SC O N T E N T S

WWWWW.J. Doyle Elected Chairman,.J. Doyle Elected Chairman,.J. Doyle Elected Chairman,.J. Doyle Elected Chairman,.J. Doyle Elected Chairman,FFFFF.W.W.W.W.W. Corrigan V. Corrigan V. Corrigan V. Corrigan V. Corrigan Vice Chairman of PPI Boardice Chairman of PPI Boardice Chairman of PPI Boardice Chairman of PPI Boardice Chairman of PPI Board 33333

TTTTT.L. Roberts Named Senior V.L. Roberts Named Senior V.L. Roberts Named Senior V.L. Roberts Named Senior V.L. Roberts Named Senior Vice Presidentice Presidentice Presidentice Presidentice Presidentas M.D. Stauffer Retires from PPI/PPICas M.D. Stauffer Retires from PPI/PPICas M.D. Stauffer Retires from PPI/PPICas M.D. Stauffer Retires from PPI/PPICas M.D. Stauffer Retires from PPI/PPIC 44444

PPI/PPIC Staff Honored in Latin AmericaPPI/PPIC Staff Honored in Latin AmericaPPI/PPIC Staff Honored in Latin AmericaPPI/PPIC Staff Honored in Latin AmericaPPI/PPIC Staff Honored in Latin America 44444

Fertilization for Cotton-Sorghum Rotations vs.Fertilization for Cotton-Sorghum Rotations vs.Fertilization for Cotton-Sorghum Rotations vs.Fertilization for Cotton-Sorghum Rotations vs.Fertilization for Cotton-Sorghum Rotations vs.Continuous Cotton (TContinuous Cotton (TContinuous Cotton (TContinuous Cotton (TContinuous Cotton (Texas)exas)exas)exas)exas) 55555

J.D. Booker, K.F. Bronson, W.J. Keeling, andC.L. Trostle

Nutrient Management of Soybeans with theNutrient Management of Soybeans with theNutrient Management of Soybeans with theNutrient Management of Soybeans with theNutrient Management of Soybeans with thePotential for Asian Soybean RustPotential for Asian Soybean RustPotential for Asian Soybean RustPotential for Asian Soybean RustPotential for Asian Soybean Rust 77777

Broadcast and Deep Band Placement ofBroadcast and Deep Band Placement ofBroadcast and Deep Band Placement ofBroadcast and Deep Band Placement ofBroadcast and Deep Band Placement ofPhosphorus for Soybeans Managed withPhosphorus for Soybeans Managed withPhosphorus for Soybeans Managed withPhosphorus for Soybeans Managed withPhosphorus for Soybeans Managed withRidge TRidge TRidge TRidge TRidge Tillage (Iowa)illage (Iowa)illage (Iowa)illage (Iowa)illage (Iowa) 88888

A.P. Mallarino and R. Borges

Management of High YManagement of High YManagement of High YManagement of High YManagement of High Yielding Canola Cultivarsielding Canola Cultivarsielding Canola Cultivarsielding Canola Cultivarsielding Canola Cultivars(Northern Great Plains)(Northern Great Plains)(Northern Great Plains)(Northern Great Plains)(Northern Great Plains) 1212121212

S. Brandt, D. Ulrich, G. Lafond, R. Kutcher,S. Malhi, and A. Johnston

Soil Fertility and FertilizersSoil Fertility and FertilizersSoil Fertility and FertilizersSoil Fertility and FertilizersSoil Fertility and Fertilizers—-—-—-—-—-Seventh Edition of Book Now ASeventh Edition of Book Now ASeventh Edition of Book Now ASeventh Edition of Book Now ASeventh Edition of Book Now Availablevailablevailablevailablevailable 1414141414

Rice Potassium Nutrition Research ProgressRice Potassium Nutrition Research ProgressRice Potassium Nutrition Research ProgressRice Potassium Nutrition Research ProgressRice Potassium Nutrition Research Progress(Missouri)(Missouri)(Missouri)(Missouri)(Missouri) 1515151515

David Dunn and Gene Stevens

InfoAg 2005 Scheduled for July 19 to 21InfoAg 2005 Scheduled for July 19 to 21InfoAg 2005 Scheduled for July 19 to 21InfoAg 2005 Scheduled for July 19 to 21InfoAg 2005 Scheduled for July 19 to 21 1717171717

Differences in Potassium RequirementDifferences in Potassium RequirementDifferences in Potassium RequirementDifferences in Potassium RequirementDifferences in Potassium Requirementand Response by Older and Modernand Response by Older and Modernand Response by Older and Modernand Response by Older and Modernand Response by Older and ModernCotton VCotton VCotton VCotton VCotton Varieties (South Carolina)arieties (South Carolina)arieties (South Carolina)arieties (South Carolina)arieties (South Carolina) 1818181818

J.J. Camberato and M.A. Jones

North Central Extension-IndustryNorth Central Extension-IndustryNorth Central Extension-IndustryNorth Central Extension-IndustryNorth Central Extension-IndustryConference Proceedings AConference Proceedings AConference Proceedings AConference Proceedings AConference Proceedings Availablevailablevailablevailablevailable 2020202020

Introducing: Introducing: Introducing: Introducing: Introducing: Be YBe YBe YBe YBe Your Own Cotton Doctorour Own Cotton Doctorour Own Cotton Doctorour Own Cotton Doctorour Own Cotton Doctor 2121212121

Annual Statement of OwnershipAnnual Statement of OwnershipAnnual Statement of OwnershipAnnual Statement of OwnershipAnnual Statement of Ownership 2121212121

What Is Sustainable Agriculture andWhat Is Sustainable Agriculture andWhat Is Sustainable Agriculture andWhat Is Sustainable Agriculture andWhat Is Sustainable Agriculture andHow Do WHow Do WHow Do WHow Do WHow Do We Do It? (California)e Do It? (California)e Do It? (California)e Do It? (California)e Do It? (California) 2222222222

Craig Kallsen

Nutrient Exclusivity in Organic Farming—Nutrient Exclusivity in Organic Farming—Nutrient Exclusivity in Organic Farming—Nutrient Exclusivity in Organic Farming—Nutrient Exclusivity in Organic Farming—Does It Offer Advantages?Does It Offer Advantages?Does It Offer Advantages?Does It Offer Advantages?Does It Offer Advantages? 2424242424

H. Kirchmann and M.H. Ryan

INTERNAINTERNAINTERNAINTERNAINTERNATIONAL SECTIONTIONAL SECTIONTIONAL SECTIONTIONAL SECTIONTIONAL SECTION

Soil TSoil TSoil TSoil TSoil Testing: A Proven Diagnostic Testing: A Proven Diagnostic Testing: A Proven Diagnostic Testing: A Proven Diagnostic Testing: A Proven Diagnostic Tooloolooloolool 2828282828Sam Portch and Mark D. Stauffer

Fertilizers to Sustain Production ofFertilizers to Sustain Production ofFertilizers to Sustain Production ofFertilizers to Sustain Production ofFertilizers to Sustain Production of100 Million Metric T100 Million Metric T100 Million Metric T100 Million Metric T100 Million Metric Tons of Grain (Argentina)ons of Grain (Argentina)ons of Grain (Argentina)ons of Grain (Argentina)ons of Grain (Argentina) 3333333333

F.O. García, G. Oliverio, F. Segovia, and G. López

New Leaf Color Chart for Effective NitrogenNew Leaf Color Chart for Effective NitrogenNew Leaf Color Chart for Effective NitrogenNew Leaf Color Chart for Effective NitrogenNew Leaf Color Chart for Effective NitrogenManagement in Rice (Southeast Asia)Management in Rice (Southeast Asia)Management in Rice (Southeast Asia)Management in Rice (Southeast Asia)Management in Rice (Southeast Asia) 3636363636

C. Witt, J.M.C.A. Pasuquin, R. Mutters, andR.J. Buresh

Potash & Phosphate Institute:Potash & Phosphate Institute:Potash & Phosphate Institute:Potash & Phosphate Institute:Potash & Phosphate Institute:Still Going Strong at 70Still Going Strong at 70Still Going Strong at 70Still Going Strong at 70Still Going Strong at 70 4040404040

B.C. Darst

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Better Crops/Vol. 89 (2005, No. 1) 3

William J. Doyle, President andChief Executive Officer (CEO)of Potash Corporation of

Saskatchewan Inc. (PotashCorp), waselected Chairman of the Potash & Phos-phate Institute (PPI) Board of Directorsat a recent meeting. Fredric W. �Fritz�Corrigan, CEO and President of Mosaic,was elected Vice Chairman of the PPIBoard.

�The extensive achievement, experi-ence, and leadership of these individualsis welcomed by the Institute as they servein these key positions,� said Dr. David W.Dibb, PPI President.

Mr. Doyle wasappointed CEO ofPotashCorp in July1999 after 12 yearsas a key member ofthe company�s man-agement team.PotashCorp is theworld�s largest inte-grated producer ofnitrogen, phosphate,

and potash. Mr. Doyle joined the companyas President of PCS Sales in 1987, assum-ing responsibility for the sales and distri-bution of all potash produced by the com-pany. In March 1995, he was appointed Ex-ecutive Vice President of PotashCorp,where he took charge of all sales for thecompany�including phosphate and nitro-gen�following a series of acquisitions. InJuly 1998, he was named President andChief Operating Officer.

Mr. Doyle serves on the boards ofCanpotex Limited and The Fertilizer

Institute (TFI). He is Chairman of the Pro-duction and International Trade Commit-tee for the International FertilizerIndustry Association (IFA). He will alsoserve as chairman of the Foundation forAgronomic Research (FAR) Board ofDirectors.

Mr. Corriganmost recently servedas Executive VicePresident of Cargill,Incorporated. Hewas Chairman ofthe Board of CargillFertilizer, Inc.,Chairman of theCargill CorporateBusiness Excellence

Committee, and a member of Cargill�sCorporate Leadership Team and CorporatePublic Affairs Committee. (Mosaic was re-cently formed by the combination of IMCGlobal with Cargill Incorporated�s cropnutrition businesses.)

After joining Cargill in 1966, Mr.Corrigan held various positions, includingPresident of Cargill�s Fertilizer Division,Cargill Worldwide Fertilizer, and Cargill�sAgriculture-Biosciences Group. Mr.Corrigan serves on the Board of Directorsof the Florida Phosphate Council and isformer Board Chairman. He also serves onthe Board of Directors and is former BoardChairman of TFI.

In other action of the PPI Board,William J. Whitacre was elected Chairmanof the Finance Committee. Mr. Whitacreis President, AgriBusiness Group, J.R.Simplot Company. BC

W.J. Doyle Elected Chairman,F.W. Corrigan Vice Chairman of PPI Board

W.J. Doyle

F.W. Corrigan

PPI/PPIC on the Web: www.ppi-ppic.org

Learn more about PPI/PPIC programs, research support, and links by visitingthe website: >www.ppi-ppic.org<. From the central website, visitors may reach

the various individual regional sites where PPI/PPIC programs are at work. BC

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4 Better Crops/Vol. 89 (2005, No. 1)

Dr. Terry L. Roberts has beenpromoted to Senior Vice Presidentof PPI/PPIC effective November 1,

2004 and International Program Coordinatorof the organization effective January 1, 2005.

Dr. Mark D. Stauffer of Saskatoon,Saskatchewan, who served as PPI SeniorVice President, International ProgramCoordinator, and President of PPIC since1994, retired at the end of 2004.

�In this action, the PPI Board of Di-rectors expressed its great appreciation toDr. Stauffer for his dedicated performanceover the past 17 years with PPI/PPIC,�said Dr. David W. Dibb, President of PPI.�Dr. Roberts has several years of experi-ence in our international programs and will

transition quickly tothese broader re-sponsibilities. Hewill continue hisleadership role inCommunicationsand Member Ser-vices as well.�

Dr. Robertsjoined the staff ofPPI/PPIC in 1989 asWestern Canada Di-

rector. In 1999, he moved to PPI headquar-ters in Norcross, Georgia. In addition tohis responsibility for Communications andMember Services, Dr. Roberts has beenPPIC Vice President for Latin AmericanPrograms and served as President andnow Vice President of the Foundation for

Agronomic Research (FAR). A native ofsouthern Alberta, he grew up in a familyowned and operated retail fertilizer busi-ness. He received a B.S.A. in Crop Science(1981) and a Ph.D. in Soil Fertility andPlant Nutrition (1985) from the Univer-sity of Saskatchewan. Dr. Roberts is a Fel-low in the American Society of Agronomy(ASA)

Dr. Stauffer joined the PPI/PPIC staffin 1988 as Western Canada Director, thenmoved in 1989 to Ontario to serve as Di-rector for Eastern Canada, Michigan, andOhio. In 1994, hebecame PPI VicePresident and thenSenior Vice Presi-dent for Interna-tional Programs andPresident of PPIC.A native of Ontario,Dr. Stauffer took hisu n d e r g r a d u a t etraining at the Uni-versity of Guelph andearned his Doctorate in Agronomy atVirginia Polytechnic Institute and StateUniversity. He worked in agricultural re-search, sales, and management in the U.S.and Canada and was a research scientistwith a major agricultural chemical com-pany in Saskatchewan before joining PPI/PPIC. Dr. Stauffer has actively served inmany community and professional orga-nizations, including ASA and the CanadianSociety of Agronomy. BC

Terry L. Roberts Named Senior Vice Presidentas Mark D. Stauffer Retires from PPI/PPIC

PPI/PPIC Staff Honored in Latin AmericaNorthern Latin America Program(INPOFOS) Director Dr. José Espinosa,were honored at the closing ceremony ofthe XVI Latin American Soil ScienceCongress and XII Colombian Congress ofSoil Science in Cartagena, Colombia. BC

Directors of two PPI/PPIC programswere recently recognized for distin-

guished activities in agronomic researchand education in Latin America.PPI/PPIC-IPI Brazil (POTAFOS)Director Dr. T. Yamada and PPI/PPIC

M.D. Stauffer

T.L. Roberts

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Better Crops/Vol. 89 (2005, No. 1) 5

T E X A S

500130/04

Crop rotation has been long recognizedas a benefit to soil and crops from thestandpoint of pest, diseases, and soil

fertility. The main rotation crop in cottoncropping in the Southern High Plains issorghum. Surprisingly, yield data on thecotton-sorghum rotation compared to con-tinuous cotton for this region is sparse. Inother regions, rotating sorghum with cot-ton has reportably helped control nema-todes in cotton. Although much soil fertil-ity information has been generated in thelast 40 years on mono-cropped sorghumand cotton, very little study has been doneon the fertilizer needs of the cotton-sor-ghum rotation.

In the 2000 cropping season, we estab-lished a limited irrigation study evaluat-ing rotation sequences of cotton-sorghum,sorghum-cotton, and continuous cotton.Fertilizer treatments included three ratesof N, two rates of P, and two rates of zinc(Zn). The main objective of this study wasto document N, P, and Zn fertilizer re-sponse for the cotton-sorghum and cotton-cotton rotations. We also tested the hy-pothesis of yield gains by rotating versusmono-cropping. We compared soil organicmatter build-up by rotating with sorghumcompared to continuous cotton.

This field research study, located at theTexas A&M University Lubbock Research& Extension Center, was in a split-plotdesign with three replicates. Main plots(eight 40-in. rows wide, by 200 ft. long)

were crop rotation: continuous cotton, cot-ton-sorghum, and sorghum-cotton. Sub-plots (eight 40-in. rows wide, by 50 ft. long)were factorial combinations of three ratesof N, two rates of P, and two rates of Znfertilizer. Crops were planted in early Mayon 40-in. wide ridges that were re-listed ev-ery spring following fall disc plowing. Soilsamples were taken every spring from the0 to 6, 6 to 12, 12 to 24, and 24 to 36 in.soil layers for extractable soil nitrate(NO3

�). The 0 to 6 in. depth was analyzedfor other nutrients such as P, potassium(K), Zn, and iron (Fe). Additionally, weanalyzed the top two layers for soil organicmatter by �loss on ignition� and for totalsoil carbon (C) and N by dry combustion.

Table 1 describes the soil test resultsand the rates of fertilizer applied. Phos-phorus (0-18-0 as H3PO4 in 2000 and in2001, 10-34-0 in 2002 and 2003), and Zn(10% EDTA-Zn) were applied pre-plantby knifing-in liquid fertilizers 3 in. deep

Fertilization for Cotton-SorghumRotations vs. Continuous CottonBy J.D. Booker, K.F. Bronson, W.J. Keeling, and C.L. Trostle

Sorghum is the main rotation crop in the 3 million acre cotton growing region of theSouthern High Plains of Texas. However, fertilizer requirements for the cotton-sorghum rotation are not well documented. We observed no rotation effect on theyield of cotton. Nitrogen (N) and phosphorus (P) fertilizer response was affected byrotation during the 4 years of this study.

CoCoCoCoCotttttttttton and soron and soron and soron and soron and sorghumghumghumghumghum plots in Texas study.

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6 Better Crops/Vol. 89 (2005, No. 1)

below the rows. The first rate of N fertilizer(soil-test and yield goal based) and half ofsecond rate (based on two times the firstrate) was knifed-in pre-plant (32-0-0, ureaammonium nitrate) at 3 in. depth, 3 in. offthe row. The second half of the higher Nrate was applied in the same manner at firstsquare in cotton and at the 12 in. heightof sorghum. The grain yield goal for sor-ghum was 4,000 lb/A and the N fertilizerto be added was 70 lb N minus 0 to 24 in.soil NO3-N, according to regional recom-mendations. The lint yield goal for cottonwas 750 lb/A and the N fertilizer to beadded was 90 lb N minus 0 to 24 in. soilNO3-N, also following regional recommen-dations. At the start of the study, the soiltested 39 lb NO3-N/A (0 to 24 in.), 20 partsper million (ppm) Mehlich 3-extractable P(0 to 6 in.), and 0.25 ppm DTPA-extract-able Zn (0 to 6 in.) See Table 1.

Soil test P in the zero P control plotstended to increase to about 30 ppm for rea-sons not clear to us. Soil test Zn in the zeroZn control plots remained between 0.25and 0.30 ppm. Soil test P and Zn in fertil-izer addition plots increased in all cases(Table 1). Spring extractable NO3-N in 0to 24 in. soil depth was on average 39 lb N/

A less in plots following sorghum comparedto continuous cotton plots.

In the establishment year of the study(2000), sorghum grain yields and cottonlint yields averaged 5,500 and 740 lb/A,respectively (data not shown). Nitrogen, P,or Zn fertilizer responses were not ob-served. Discussion from this point on willfocus on the three seasons of data whererotation data applies, from 2001-2003.

Cotton lint yields were similar follow-ing sorghum compared to cotton followingcotton for all 3 years (Table 2). Onaverage, 39 lb more fertilizer-N/A was ap-plied to the 1X N rate for cotton followingsorghum compared to continuous cotton(Table 1). In 2001, sorghum grain yieldswere only about half of the expected level.In 2002 and 2003, sorghum yields weregreater and similar to the 4,000 lb/A yieldgoal. Continuous cotton lint yields equaledthe expected goal of 750 lb/A in 2001 and2003 and cotton in both rotations exceededthe yield goal in 2002. The summer of 2001was hotter and drier than average and bothcrops suffered from water stress.

Nitrogen response was observed in all3 years in cotton following sorghum, butwas absent in the cotton-cotton rotation

TTTTTable 1. able 1. able 1. able 1. able 1. Soil test results (fertilized plots after 2000) and N, P, and Zn fertilizer rates applied to cottonfollowing cotton, cotton following sorghum, and sorghum following cotton.

Soil 1st N 2nd (2x)Previous NO

3-N rate N rate Soil P P rate Soil Zn, Zn rate

Crop crop - - - - - - - - - - - - lb/A - - - - - - - - - - - - ppm lb P2O

5/A ppm lb Zn/A

Spring 2000Cotton N/A 39 51 102 20 45 0.25 2Sorghum N/A 39 31 62 20 40 0.25 4

Spring 2001Cotton Cotton 99 0 0 35 0 0.33 2Cotton Sorghum 22 68 136 27 30 0.36 0Sorghum Cotton 75 0 0 28 20 0.45 0

Spring 2002Cotton Cotton 52 38 76 39 0 0.32 0Cotton Sorghum 20 70 140 29 30 1.4 0Sorghum Cotton 54 16 32 30 20 0.41 2

Spring 2003Cotton Cotton 23 67 135 46 0 0.38 0Cotton Sorghum 14 76 153 39 0 0.71 0Sorghum Cotton 24 46 93 35 0 0.53 2

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Better Crops/Vol. 89 (2005, No. 1) 7

continuous cotton. Nevertheless, no posi-tive rotation effect in yield was observed.

Conservation compliance and protec-tion of cotton seedlings is considered an-other benefit of rotating sorghum withcotton. Soil organic N and C (average of0.06 and 0.55 %, respectively) analyzedfrom spring 2002 soil samples did not yetshow rotation effects after 3 years and oneor two sorghum crops. Soil organic matterbuildup, therefore, probably requires sev-eral years of cotton-sorghum cropping. BC

Mr. Booker is Assistant Research Scientist,Dr. Bronson (e-mail: [email protected]) isAssociate Professor, and Dr. Keeling is Professor,with Texas A&M University (TAMU), TexasAgricultural Experiment Station. Dr. Trostle isAssistant Professor, TAMU, Texas CooperativeExtension. All are located in Lubbock, Texas.

TTTTTable 2.able 2.able 2.able 2.able 2. Yields of cotton and sorghum as affected by previous crop and N, P, or Znfertilizer.

2001 Standard2001 2000 Yields deviation N P ZnCrop Crop - - - - - - - lb/A - - - - - - - response response response

Cotton Cotton 765 79 No Yes NoCotton Sorghum 630 79 Yes No NoSorghum Cotton 2,356 410 No No No

2002 Crop 2001 Crop 2002 Yields

Cotton Cotton 1,086 42 No No NoCotton Sorghum 1,096 42 Yes No NoSorghum Cotton 5,096 487 Yes No No

2003 Crop 2002 Crop 2003 Yields

Cotton Cotton 763 166 No Yes NoCotton Sorghum 654 201 Yes No NoSorghum Cotton 4,095 880 No No No

(Table 2). Grain sorghum responded to Nfertility in 2002 only. Phosphorus responsewas observed in continuous cotton only,and only in 2001 and 2003. No Zn fertilityresponses were observed in any rotation orin any year.

Important in understanding N fertil-izer response on the Acuff sandy clay loamsoil is that about 50 lb N/A is availablefrom mineralization of soil organic matterand from previous cotton crop leaf litter.Sorghum residue, on the other hand, maybe biologically �tieing-up� or immobiliz-ing N. This may contribute to the moreconsistent N fertilizer responses in cottonfollowing sorghum compared to cotton af-ter cotton. As N fertilizer recommenda-tions for these cropping systems are re-fined, N credits may be needed for cottonleaf-fall and N debits for sorghum residue.Lack of P response in most rotations isprobably because soil test P was near theregional recommended critical level of 33ppm (Table 1). Soil Zn was likewise nearthe critical levels of 0.29 ppm for cottonand sorghum (Table 1).

The lack of a positive cotton lint yieldresponse following sorghum compared tomono-cropped cotton was unexpected. Inthe stormy spring of 2003, the groundcover of about 30% of sorghum residueprotected cotton seedlings from wind andblowing sand damage suffered in the

Nutrient Management of Soybeanswith the Potential for Asian RustInfection

Asian soybean rust has been identifiedin the U.S., and there are many questionsabout how it will affect production. Thefocus has been on fungicides andgenetic development. For an article and re-lated information about how plant nutri-tion might be a factor, check the PPI/PPICwebsite at: >www.ppi-ppic.org<.

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8 Better Crops/Vol. 89 (2005, No. 1)

I O W A

ing. The band control received a coulter-knife pass without fertilizer.

Soybean response to direct P applica-tion was evaluated in seven trials (Sites 1through 7). The treatments were appliedin the fall (October or November) afterharvesting the previous corn crop and be-fore soils had frozen. At the remainingseven trials (Sites 8 through 14), P wasapplied 1 year earlier (in the fall prior tothe previous corn crop).

Soil samples were collected immedi-ately before applying P treatments. Soilsamples, comprised of 16 cores each, werecollected from a depth of 0 to 6 in. Onesample was collected from the ridges andanother between the ridges (or valleys). AtSites 1 through 7 (direct fertilization), com-posite soil samples were collected from eachexperimental area. At Sites 8 through 14(residual fertility), separate compositesamples were collected from fertilized andunfertilized plots. Samples were analyzedfor P with the Bray P-1 test.

Aboveground portions of 10 soybeanplants were sampled from each plot at theV5 to V6 growth stages. Total P concen-trations in the plant tissue were measuredand total P uptake calculated, based on drymatter accumulation. Grain yields werecorrected to 13% moisture.

Soybean Grain Yield. As Table 1shows, statistically significant grain yield

Fourteen trials with soybeans wereevaluated in farmer fields managedwith ridge-till during 3 years. All

fields had been planted to corn the previ-ous year, and the fields had 2 to 7 year his-tories of ridge tillage. Crop and soil man-agement practices were those used by eachfarmer, except for P and potassium (K) fer-tilization. Row spacing was 38 in. exceptfor Site 3, where it was 36 in.

Phosphorus rates were 0, 29, and 115lb P2O5/A, applied as granular triple super-phosphate (0-46-0). The highest P rateapproximately represented the 2-year ratecurrently recommended by Iowa StateUniversity for the corn-soybean rotationwhen soil test P (STP) is in the Low inter-pretation class (9 to 15 parts per million[ppm]), Bray P-1 or Mehlich-3 tests.

Placement methods were broadcastand deep bands. The bands were approxi-mately 6 to 8 in. deep and 1 in. wide. Band-ing equipment placed the fertilizer eitherthrough a vertical slit opened from the topof the ridge or through one ridge shoulder.The coulter-knife combinations openedand closed narrow slits (1 to 2 in.) thatcaused a minimum amount of disturbanceof the ridge and placed the band 2 to 3 in.below the planned seeding depth, approxi-mately under the planned seed row. Thebroadcast control received no fertilizer andthe ridges were not disturbed until plant-

Broadcast and Deep Band Placement ofPhosphorus for Soybeans Managed withRidge TillageBy A.P. Mallarino and R. Borges

Phosphorus (P) fertilization frequently increases yield of soybean on low P-testingsoils in ridge-till systems in Iowa. Yields associated with broadcast and banded Papplications usually do not differ. However, banded P often increases early P uptakemore than broadcast P.

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Better Crops/Vol. 89 (2005, No. 1) 9

responses occurred at four sites: Sites 1 and2 (P applied before soybean) and Sites 10and 13 (P applied prior to the previousyear�s corn crop). Yield response to P fer-tilization reached a maximum at the low-est rate of applied P (29 lb P2O5/A). Dif-ferences between placement methods wereobserved at two sites. At Site 2, both place-ment methods increased soybean yield, butbanded P provided a small additional in-crease. At Site 10, only the broadcast ap-plication significantly increased yield. Theinconsistent yield response to P placementmethod is in contrast with the benefit ofdeep-band K placement shown in a simi-lar Iowa study (Mallarino et al., 2001).

Soils of the four responsive sites tested7 to 18 ppm Bray P-1, according to aver-age results for soil samples collected in andbetween the ridges (Table 2). Three of theresponsive sites tested Very Low or Lowand one tested Optimum (16 to 20 ppm)according to current Iowa State Universityinterpretations (Sawyer et al., 2002).Across the entire study, eight sites testedVery Low or Low. According to current soiltest interpretations, soybeans grown on

soils testing in these ranges would be con-sidered likely to respond to P fertilization.There is a 25% or lower probability of asmall response in the Optimum class, forwhich maintenance fertilization is recom-mended.

With only one exception, soil samplestaken from the ridges were higher in P thanthose taken between the ridges (valleys).This is consistent with findings from otherinvestigations in Iowa with corn (Mallarinoet al., 2001) as well as studies from otherstates. A reclassification of the sites ac-

cording to STPresults fromsamples takensolely from theridges indi-cated that onlysix sites testedVery Low orLow (three ofwhich re-sponded sig-nificantly to Pfertilization)while fourtested Opti-mum (one ofwhich was re-s p o n s i v e ) .These results,and similar re-sults for ridge-till corn notshown in thisarticle, were

BandingBandingBandingBandingBanding of P for ridge-till soybeans may increase earlyplant P uptake.

TTTTTable 1.able 1.able 1.able 1.able 1. Soybean grain yield and P uptake at the V5 to V6 growth stages asaffected by P fertilization and placement. Data are averages of twoapplication rates (29 and 115 lb P

2O

5) because yields for these two rates

were statistically similar at all sites.Change in Change in

Control soybean grain yield Control P uptakeP timing Site yield Broadcast Band P uptake Broadcast Band

- - - - - - - - - - bu/A - - - - - - - - - - - - - - - - 10-5 lb P2O

5/plant - - - - - -

Direct 1 32.3 3.33.33.33.33.3 5.55.55.55.55.5 1.59 0.390.390.390.390.39 0.470.470.470.470.472 44.0 3.83.83.83.83.8 4.34.34.34.34.3 2.04 0.250.250.250.250.2511111 1.091.091.091.091.0911111

3 59.6 2.7 -1.0 4.13 0.06 0.430.430.430.430.434 40.2 -0.3 1.4 1.94 0.180.180.180.180.18 0.570.570.570.570.575 49.2 1.0 -0.9 1.61 -0.20 0.320.320.320.320.326 44.6 0.7 1.4 2.54 -0.02 0.317 45.1 1.1 0.9 3.85 0.320.320.320.320.32 0.610.610.610.610.61

Residual 8 47.4 2.2 3.0 1.98 -0.25 0.109 43.4 -1.8 -0.6 2.67 -0.16 0.620.620.620.620.6210 42.8 1.51.51.51.51.5 0.9 2.68 -0.05 0.480.480.480.480.4811 43.7 0.1 2.2 3.64 -0.12 0.3612 47.7 0.4 1.9 1.90 0.03 0.0713 30.7 2.72.72.72.72.7 2.52.52.52.52.5 2.82 0.20 0.0814 33.8 4.5 1.4 3.02 -0.15 -0.46

1P uptake at the higher P application rate.Bold type indicates statistically different from the control (p<0.1).

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10 Better Crops/Vol. 89 (2005, No. 1)

used to update Iowa soil sampling recom-mendations for the ridge-till system (Saw-yer et al., 2003). The updated guidelinesrecommend taking 0 to 6 in. samples fromthe top and shoulders of the ridges (avoid-ing valleys) to improve the prediction ofyield response. Consideration of deepsamples (6 to 12 in., not shown) indicatedno benefits in prediction of response.Higher STP results for the ridges may alsoexplain why the lowest rate of applied P(29 lb P2O5/A) was sufficient for statisti-cally maximum yields. Only one site (Site1) tested Very Low in the ridge, and thislevel was borderline with the Low class.

Early Season P Uptake. Uptake of Pby soybean plants at the V5 to V6 growthstage was often influenced by P fertiliza-tion (Table 1). This was the result of theadditive effects of slight (typically insig-nificant) responses in early plant dry mat-ter accumulation and tissue P concentra-tion (not shown). With the exception ofSite 2, P applied at the lower rate (29 lbP2O5/A) increased uptake to the same ex-tent as the higher rate (115 lb P2O5/A).Consequently, P uptake values reported inTable 1 represent the lower P applicationrate, except for Site 2, where reported Puptake is associated with the higher fer-tilization rate.

When P was applied prior to the soy-bean year, P uptake increased significantlyat most sites (six of the seven sites). At twoof these sites (Sites 3 and 5), banded P in-creased soybean P uptake when broadcastP did not, and banded P led to greater Puptake than broadcast P at other respon-sive sites. When P was applied prior to corngrown the previous year, P uptake in-creased significantly at two of the sevensites (Sites 9 and 10). At Site 9, responsewas observed to banded P only. At site 10,both broadcast and banded P significantlyincreased P uptake when results were av-eraged over P rates (not shown). Across allsites, increased P uptake was observed onsoils ranging from Very Low to Very Highin STP. On average, P uptake was greaterfor banded P than for broadcast P.

Changes in Soil Test P. To evaluatechanges in STP over time, seven sites wereexamined where P had been applied priorto the previous year�s corn crop (Sites 8through 14). The low P application rateseldom changed STP levels�an expectedresult because this rate was lower than theP removal rate associated with grain har-vest. Consequently, only STP changes as-sociated with the high P rate (115 lb P2O5/A) are presented.When fertilizer P wasbroadcast, STP levels in the ridge did not

TTTTTable 2.able 2.able 2.able 2.able 2. Initial Bray P-1 soil test levels and soil pH for various sampling positions. All levels are forsamples taken from a 0 to 6 in. depth.

Years in Soil test P levels Soil pHP Timing Site ridge-till In ridges Between ridges In and between ridges in and between ridges

- - - - - - - - - - - - - - - - - - - - ppm - - - - - - - - - - - - - - - - - - - -Direct 1 6 8 7 7 6.5

2 5 14 9 11 6.13 2 66 56 61 6.54 5 25 15 20 5.65 3 26 20 23 6.46 4 20 7 14 6.17 6 12 7 10 6.4

Residual 8 7 16 16 16 7.09 4 17 8 13 6.110 6 13 9 11 6.511 6 10 8 9 6.312 4 13 8 11 6.013 5 20 17 18 6.914 5 24 15 20 6.4

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Better Crops/Vol. 89 (2005, No. 1) 11

change significantly compared with the non-fertilized control. However, STP levels in thevalleys between the ridges increased signifi-cantly at five sites (Figure 1).

Banded P significantly increased STPin the ridge at six of the seven sites (Fig-ure 1). However, it increased STP betweenthe ridges at only one site (Site 13).

The way in which P placement altersSTP has implications on environmentalnutrient management. Concentrated sur-face water flow occurs between ridges,mainly on trafficked areas. Becausebanded P seldom increases STP betweenridges and also places P below the surface,this placement method is expected to re-duce the chances for offsite P transportinto water bodies.

SummarySoybean yield response to P fertiliza-

tion was frequent in low-testing soils, in-frequent in soils testing Optimum, and didnot occur in high-testing soils. Collectingsoil samples solely from ridges improvedthe prediction of yield response to appliedP. When responses occurred, STP in theridges was 20 ppm or less. The P placementmethod did not influence yield responseconsistently, which was in contrast withthe clear benefits of deep K placementobserved in parallel Iowa studies with cornand soybean. However, early plant uptakeof P by soybean was increased more fre-quently and to a greater extent by bandedP than by broadcast P. Furthermore,banded P increased STP primarily in theridges, while broadcast P increased STPlevels primarily in the soil between theridges. Therefore, banded P may notincrease grain yield more than broadcastP, but it is more likely to stimulate earlyplant P uptake and is a viable option forreducing the risk of P loss from ridge-tillfields. BC

Dr. Mallarino (e-mail: [email protected]) isProfessor, Soil Fertility Research and Extension,Iowa State University, Ames.

Dr. Borges is Assistant Professor, Department ofAgronomy, University of Wisconsin, Madison.PPI/FAR Research Project IA-11F

ReferencesMallarino, A.P., R. Borges, and D. Wittry. 2001. Corn

and soybean response to potassium fertilizationand placement. p. 5-11. In North-Central Ex-tension-Industry Soil Fertility Conference. Pro-ceedings. Vol. 17. Des Moines, Iowa.

Sawyer, S., A.P. Mallarino, and R. Killorn. 2003. Takea good soil sample to help make good decisions.Publ. Pm-287 (Rev.). Iowa State Univ. Exten-sion.

Sawyer, J.E., A.P. Mallarino, R. Killorn, and S.K.Barnhart. 2002. General guide for crop nutri-ent recommendations in Iowa. Publ. Pm-1688(Rev.). Iowa State Univ. Extension.

FFFFFigurigurigurigurigure 1.e 1.e 1.e 1.e 1. Effect of broadcast and banded P (115lb P

2O

5/A) on soil-test P of ridges and

areas between ridges (valleys) measuredafter crop harvest. Differencespresented are between fertilized andunfertilized treatments. Values followedby an asterisk represent statisticallysignificant (p<0.1) changes due tofertilization when compared tounfertilized treatments.

2

108 7 8

1

7

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5*

11*7*

3

11*

-10

-5

0

5

10

15

20

25

30

35

40

37*

14*12

31*

12*

22*

28*

5

0

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11*

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-5

0

5

10

15

20

25

30

35

40

8 9 10 11 12 13 14

Site

So

il t

est

P d

iffe

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, p

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Broadcast P

Banded P

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Between ridges

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12 Better Crops/Vol. 89 (2005, No. 1)

Management of High YieldingCanola CulitvarsBy S. Brandt, D. Ulrich, G. Lafond, R. Kutcher, S. Malhi, and A. Johnston

To maximize seed yield, high yielding canola cultivars should be receiving morefertilizer than is currently being applied on the northern Great Plains.

Registered open pollinated andhybrid canola currently grownon the northern Great Plains pro-

vide higher yield potential than conven-tional varieties for farmers. However, themanagement strategies necessary toachieve optimum yield are not well under-stood. Nutrients frequently restrict theyield of canola and it is reasonable to ex-pect that higher fertilizer application rateswould be required to support higher yieldspossible with newer cultivars.

Seed of hybrid canola cultivars is sev-eral times more expensive than open polli-nated types, and therefore reduced seed-ing rates is seen as a possible area for cut-ting input costs. Research trials were con-ducted over a three-year period to evalu-ate whether combinations of fungicides,seed rates and fertility levels needed to bealtered, and whether increased rates of fer-tilizer nitrogen (N) would be required tooptimize the yield of newer high yieldingcanola cultivars.

Field trials were conducted inSaskatchewan at Melfort (clay), IndianHead (heavy clay), and Scott (loam), be-tween 1999 and 2001. Canola was directseeded into wheat stubble using low distur-bance openers with on row packers. Atseeding, N was applied as banded urea,along with a phosphorus (P), potassium(K), and sulfur (S) fertilizer blend. Treat-ments in the experiment were two culti-vars (hybrid and open pollinated), threefertility levels that supplied 2/3, 1.0, and 11/3 times a target level of soil test recom-mendation for N, P, K, and S, and three

NORTHERN GREAT PL AINS

seeding rates: 2.5, 5.0, and 7.5 lb/A. A fun-gicide treatment included an applicationof Ronilan EG (vinclozolin) to controlsclerotinia stem rot. At Melfort only, therewas an additional application of Quadris(azoxystobin) for blackleg. Backgroundlevels of N and S to 24 in. depth, and Pand K to 6 in., were measured each year toestablish residual soil fertility. Residual soilN varied from 18 to 52 lb/A depending onlocation and year.

In a second experiment, six N rateswere applied (0, 27, 54, 80, 107, and 134lb/A) as urea using the same open polli-nated and hybrid cultivars as above. Re-sidual soil N varied from 22 to 67 lb/A. Asingle rate of P-K-S blend was applied,with a seed rate of 6.2 lb/A. Growing sea-son moisture conditions were above normalin 1999, near normal in 2000, and belownormal in 2001.

The two cultivars responded consis-tently to seeding rate, nutrient level, andfungicide across all location and years, de-spite the hybrid producing greater seedyield than open pollinated cultivar. Be-cause the same weight of seed was sownfor both cultivars, and the seed size for thehybrid was greater than that of the openpollinated cultivar by an average of 40%,the number of hybrid seeds sown waslower. This was the major factor affectingcultivar differences in plant density (Table1).

Generally, the hybrid had lower densi-ties than the open pollinated cultivar, whilethe reverse occurred for percent establish-ment (% of seeds sown that emerged).

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Better Crops/Vol. 89 (2005, No. 1) 13

Biomass and grain yield with the hybridwas similar or higher than the open polli-nated cultivar at all locations and years,and averaged 12% higher. With above nor-mal moisture during 1999 grain yield dif-ferences between cultivars were relativelysmall (0.9 bu/A), while in the dry year 2001grain yield differences between cultivarswere quite large (5.5 bu/A). These resultsprovide good evidence that canola hybridsdo not require more available moisture toexpress a yield advantage, and possibly aremore drought tolerant.

Both increased seed rate and fertilitylevel generally increased yield (Table 2).However, for the low fertility treatment,yield increased when seed rate wasincreased from 2.5 to 5.0 lb/A, with nofurther increase at 7.5 lb/A. Similarly, at2.5 lb/A seed rate, yield was higher for themid than low fertility level, but further in-creases in yield were not detected for thehigh fertility treatment. At the 5.0 and7.5 lb/A seed rates yield continued to

increase with each increase in fer-tility. This provides strong evidencethat higher plant densities are re-quired to take advantage of higherfertility, and vice versa. The lack ofan interaction of cultivar with seedrate or fertility level suggests thatboth canola cultivars require simi-lar seed rates and fertility to opti-mize yield.

In the N rate trial, the interac-tion of cultivar with location-yearand N rate was significant. The gen-eral trend was for the yield of the

hybrid to be equal to, or greater than, theyield of the open pollinated cultivar at allN rates. Under dry conditions in 2001, seedyield of both cultivars was maximized with105 lb/A of applied N (Figure 1). But yieldwas not maximized even with the highestN rate under near normal moisture condi-tions in 2000. Averaged over all location-years, the seed yield of the hybrid canolawas maximized at 40 bu/A with 119 lb/Aof fertilizer N/A, while the yield of theopen pollinated was maximized at 34 bu/A with 132 lb N/A. The hybrid outyieldedthe open pollinated cultivar at all levels ofapplied N indicating that it used N moreefficiently. The relative difference in seedyield between the two cultivars increasedas N supply increased, yielding 10% morewithout N application and 17% more when98 lb N/A was applied.

TTTTTable 1.able 1.able 1.able 1.able 1. Plant densities, plant establishment, biomassproduction, and seed yield of hybrid and openpollinated canola at Scott, Melfort, and IndianHead during 1999-2001. (Data are the mean ofthree seed rates and three fertility levels).

Factor1 Hybrid Open Pollinated

Plant density, no./sq yd 67b 79aPercent establishment, % of seed planted 53 47Biomass yield, tons/A 3.32a 2.95bGrain yield, bu/A 32.6a 29.0b1Values in rows followed by a different letter are significantly differentat p=0.05.

TTTTTable 2.able 2.able 2.able 2.able 2. Seed yield (bu/A) with three fertilityrates and three seed rates averagedacross 7 location-years. (Means for twocultivars and two fungicide treatments).

Fertility Seed rate, lb/A 1

level 2.5 5.0 7.5

Low 26.8e 30.1d 29.8dMid 29.1d 31.9c 33.6bHigh 29.9d 33.7b 35.4a

1Values in rows followed by a different letter aresignificantly different at p=0.05.

0.0

10.0

20.0

30.0

40.0

50.0

60.0

0 50 100 150

N rate, lb N/A

Can

ola

yiel

d, b

u/A

Hybrid Open pollinated

2001

2000

FFFFFigurigurigurigurigure 1.e 1.e 1.e 1.e 1. Seed yield of hybrid and open pollinatedcanola as a function of applied N undernormal to above normal moistureconditions in 2000 and below normalmoisture conditions in 2001.

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14 Better Crops/Vol. 89 (2005, No. 1)

In this study, despite an average yieldadvantage of 3.6 bu/A for the hybrid overthe open pollinated cultivar and greateradvantage under dry conditions, both cul-tivars were consistent in their response toseed rate, nutrient level, and fungicide.Fungicide generally failed to increase yieldin our trials since disease levels were insig-nificant. While yields generally increasedwith increasing fertility and increased seedrate, the seed yield response to high fertil-ity occurred only with high seed rates.

The N response results indicate thattarget N levels for canola grown on wheatstubble in moisture-limited environmentsshould be the same for a higher yieldinghybrid as they are for a high yielding openpollinated cultivar. The results also suggest

that high yielding cultivars should be re-ceiving more fertilizer to maximize seedyield than is currently being applied bymany farmers. When adequately fertilizedwith N, greater N use efficiency of hybridcanola results in greater seed yields thanthe open pollinated cultivar at all location-years, despite a higher seed cost. BC

Mr. Brandt ([email protected]) and Mr. Ulrichare agronomists with Agriculture and Agri-FoodCanada in Scott, SK. Dr. Lafond is an agronomistwith Agriculture and Agri-Food Canada in IndianHead, SK. Dr. Kutcher is a plant pathologist andDr. Malhi is a soil scientist with Agriculture andAgri-Food Canada in Melfort, SK. Dr. Johnstonis PPI/PPIC Northern Great Plains Directorlocated in Saskatoon, SK.PPI/FAR Research Project SK-24

of Soil Science,North CarolinaState University.Dr. Beaton is nowretired after a longand distinguishedcareer in agro-nomic research and education. Contribu-tions to the book by Dr. Havlin and Dr.Beaton serve to further its effectiveness asa teaching tool.

The new edition, copyright 2005, con-tains 528 pages, with 13 chapters coveringa range of topics with reference to biologi-cal, chemical, and physical properties af-fecting nutrient availability.

Soil Fertility and Fertilizers, SeventhEdition (ISBN 0-13-027824-6), is availablefrom Pearson Education/Prentice-Hall,Inc., Upper Saddle River, New Jersey. Costof the book is US$110.00 plus shipping.For single copy purchase in the U.S., call(800) 811-0912; in Canada, call (800) 567-3800.

Additional information is available at:>www.prenhall.com<. BC

With increased attention tominimizing the environmentalimpact of soil and fertilizer man-

agement, the Seventh Edition of the popu-lar text Soil Fertility and Fertilizers: AnIntroduction to Nutrient Management, isnow available. Long regarded as the lead-ing book in its field, this volume providesa basic introduction to the biological,chemical, and physical properties affect-ing soil fertility and plant nutrition. It cov-ers all aspects of nutrient management forprofitable crop production.

The Seventh Edition has been substan-tially revised to reflect rapidly advancingknowledge and technologies in both plantnutrition and nutrition management. It isconsidered the most comprehensive trea-tise on soil fertility and nutrient manage-ment on the market today.

Authors of the book are Dr. John L.Havlin, Dr. James D. Beaton, Dr. SamuelL. Tisdale, and Dr. Werner L. Nelson. Dr.Tisdale and Dr. Nelson, both now deceased,were authors of the first edition of the textin 1956. Dr. Havlin is with the Department

Soil Fertility and Fertilizers�Seventh Edition of Book Now Available

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Better Crops/Vol. 89 (2005, No. 1) 15

M I S S O U R I

Missouri has a long history of riceproduction, going back to 1910when the crop was first grown in

the southeast region of the state. From this40-acre start, rice acreage has increasedsteadily over the years to over 200,000 acrescurrently. The statewide average yield was110 bu/A in 1997 and increased to over 141bu/A in 2004. Traditionally, nitrogen (N)management has been given top priorityby farmers. But with increased yields androtations with soybeans, K fertility is in-creasingly being recognized as a yield limi-tation in some Missouri rice fields.

Research conducted by the Universityof Missouri is now highlighting the impor-tance of K in rice production. Historically,soil test-based fertilizer recommendationsfor rice grown in Missouri were adaptedfrom work in the surrounding states ofArkansas and Mississippi. As productionincreased, a need for soil test recommen-dations specific to Missouri soils was rec-ognized. Missouri uses a 1 N ammoniumacetate (NH4OAc) extraction for K, whileArkansas uses the Mehlich-3 extractantand Mississippi uses the Lancaster extrac-tant. Initial soil testing and soil fertilityresearch in Missouri focused on improvingsoil test recommendations for K and hasnow expanded to the diagnosis and correc-tion of K deficiency at mid-season.

Rice production in the Bootheel regionof southeast Missouri is on silt loam soilswest of Crowley�s Ridge, and clayey soilsgenerally found to the east of Crowley�sRidge. The Sharkey clay soils (Vertic

Rice Potassium NutritionResearch ProgressBy David Dunn and Gene Stevens

Recent Missouri research has shown significant rice response to potassium (K)fertilization applied pre-plant or at mid-season on silt loam soils. Soil test K interpre-tations and fertilizer recommendations for rice were increased.

Haplaquepts) generally have high nativeavailable K levels (500 to 600 lb K/A) anddo not require K fertilization. Many ofthese clayey soils have been recently landleveled and have a limited history of riceproduction. If intensive rice and soybeanproduction continues on these soils, theywill eventually require K fertilization. Thesilt loam to silty clay loam soils with alonger history of rice production often re-quire K fertilization. This article focuseson drill-seeded rice grown on silt loams us-ing the delayed-flood management system(i.e., flooded at the 5-leaf stage, 20 to 30days after emergence, after urea is appliedto a dry soil surface).

Soil test K management. Potassiumdeficiency in rice can reduce grain yieldsand increase lodging. Visual symptoms ofK deficiency in rice first appear in olderleaves (Figure 1). These symptoms include

FFFFFigurigurigurigurigure 1.e 1.e 1.e 1.e 1. Brown areas on leaf margins and tips inrice are a visual indicator of Kdeficiency.

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16 Better Crops/Vol. 89 (2005, No. 1)

a yellowing of leaf tips, decreased diseaseresistance, and reduced yields. Increasedstalk strength and decreased lodging areassociated with proper K nutrition. Whenthis study began, the University of Mis-souri soil test critical level for K (lb/A) was5 x cation exchange capacity (CEC) basedon a 1 N NH4OAc extraction. During thelate 1990s, Missouri rice producers begangrowing Baldo, a variety grown for a special-ized Mediterranean and west Asian market.This variety is much taller than the semi-dwarf varieties typically grown. Agrono-mists from Italy recommended applyingmid-season K applications on Baldo to in-crease stalk strength and reduce lodging.

To test this management strategy un-der Missouri conditions, a 2-year evalua-tion of pre-plant and midseason K fertili-zation strategies was undertaken on aCrowley silt loam soil (Typic Albaqualf)having 110 lb NH4OAc extractable K/A.A single pre-plant (48 lb K2O/A) applica-tion was compared to two 24 lb K2O/Aapplications at mid-season, using potas-sium chloride (KCl) as the K source. Twofoliar treatments were also evaluated: 1)two applications of 12 lb K2O/A aspotassium nitrate (KNO3), and 2) two fo-liar applications of urea (1.3 lb N/A). Theurea treatment was included to allow sepa-ration of the effects of N and K in theKNO3 treatment. The results for the foliarurea treatment were identical to that ofthe untreated check and will not be

discussed further. Response of Baldo wascompared to Bengal, which is consideredsusceptible to K deficiency.

The results of these investigationswere: 1) pre-plant and mid-season K ap-plications increased rice yields on a soilwhere K fertilization was not expected toincrease yields (Figure 2), 2) Visual defi-ciency symptoms were sometimes observedat mid-season. Tissue K analysis of flagleaves at mid-season did not reveal signifi-cant differences between treatments (datanot shown) and was not an effective toolfor diagnosing K deficiency in rice, and 3)Lodging of Baldo was significantly re-duced by foliar applications of KNO3 atmidseason (Figure 3). No lodging of Ben-gal was observed.

These findings prompted a more de-tailed K rate study beginning in 2001.Methods to diagnose mid-season K defi-ciency were also evaluated as part of thestudy. Three rates of pre-plant K fertiliza-tion were compared (0, 50, and 200 lb K2O/A). When relative yields were compared,the 50 lb K2O/A rate provided 95% of themaximum yield (Figure 4). As a result ofthis study, the critical level for soil test rec-ommendations was increased to 125 lb ofavailable K/A + (5 x CEC) in 2003. Compari-son of our results with those in Arkansas,Louisiana, and Mississippi indicate that thisnew soil test K interpretation level is similarto the interpretations in those states.

Monitoring rice tissue K. Plant tissuesamples were collected for K analyses from

FFFFFigurigurigurigurigure 3.e 3.e 3.e 3.e 3. Effect of K treatments on lodging ofBaldo rice variety averaged across 1999and 2000 at Qulin, Missouri.

FFFFFigurigurigurigurigure 2.e 2.e 2.e 2.e 2. Relative yields for K treatments of Baldoand Bengal rice averaged across 1999and 2000 at Qulin, Missouri.

0

10

20

30

40

50

Check Preplant Midseason Foliar

K fertilizer application method

Pla

nt

lod

gin

g, %

Initial soil test K = 110 lb/A.

80

85

90

95

100

Untreated Preplant Midseason dry Foliar

K fertilizer application method

Re

lati

ve y

ield

, %

BengalBaldo

Initial soil

test K =

110 lb/A.

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Better Crops/Vol. 89 (2005, No. 1) 17

each plot every two weeks during the grow-ing season beginning at first tiller and con-tinued until harvest. Samples were dividedinto plant components (i.e. upper leaf,lower leaf, stalk, and whole above-groundplant). Correlation analyses were madebetween yields and plant tissue K levels(Table 1). Plant tissue testing clearlyshowed the effect of K fertilization. At firsttiller, only the whole plant was analyzed.At this growth stage, untreated checkplants (0 K) had lower K concentrationsthan plants that received 50 and 200 lbK2O/A. At internode elongation, the riceplants were divided into the following plantparts: stem, flag leaf, lowest leaf, andwhole plant.

Correlations between plant K and yieldwere generally better in 2003 than 2002(Table 1). The best correlation in 2003 wasfor whole plant at first tiller growth stage.Tissue K levels of lower leaves were bettercorrelated to grain yields than were K lev-els of flag leaves. Leaf K concentrationswere greatest in the upper leaves, but thelowest leaves showed the most differencesbetween K fertilizer treatments. At inter-node elongation, all of the leaves had Klevels above the critical sufficiency level of1.0%. Potassium content of stems alsoreflected K treatment differences at panicleinitiation. Whole plant tissue K contentincreased with increasing K fertilization.Stem K content at 10% heading alsoclosely reflected K treatment differences.

FFFFFigurigurigurigurigure 4.e 4.e 4.e 4.e 4. Effect of preplant K fertilizer rates onrelative rice yields in tissue K monitoringexperiments in 2002 and 2003 atQulin, Missouri.

50

60

70

80

90

100

0 50 200

K fertilizer rate, lb K2O/A

Re

lati

ve y

ield

, %

Initial soil test K = 115 lb/A.

The K content of heads was affected errati-cally by K fertilization, and K levels of headswere poorly correlated to yields.

In summary, tests showed that pre-plant and mid-season K applications in-creased rice yields on soils where K fertili-zation was not previously expected to havethat effect. This prompted the Universityof Missouri to increase critical soil test K(lb/A) from 5 x CEC to 125 lb extractableK/A + (5 x CEC). Tissue testing showedthat K concentrations in lower rice leaveswere better for measuring K status thantissue K in flag leaves. BC

Mr. Dunn ([email protected]) is SoilLaboratory Supervisor and Dr. Stevens([email protected]) is Crop ProductionSpecialist with the University of Missouri, locatedat the Delta Research Center, Portageville.

TTTTTable 1.able 1.able 1.able 1.able 1. Correlation of plant tissue K levels withgrain yields in 2002 and 2003 atQulin, Missouri.

r2 valueGrowth stage Plant part 2002 2003

First tiller Whole 0.22 0.54Internode elongation Whole 0.27 0.37

Flag leaf 0.07 0.23Lowest leaf 0.38 0.39Stem 0.07 0.30

10% Heading Whole 0.25 0.32Flag leaf 0.06 0.07Lowest leaf 0.45 0.39Stem 0.11 0.41Head 0.001 0.003

InfoAg 2005 Scheduled for July 19 to 21The seventh national/international

InfoAg Conference is set for July 19 to 21in Springfield, Illinois. Co-organized byPPI and the Foundation for AgronomicResearch (FAR), the program will focus ona broad range of crop and soil manage-ment systems. More details will be avail-able at the website: >www.infoag.org<.Or contact Dr. Harold F. Reetz by e-mailat: [email protected].

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18 Better Crops/Vol. 89 (2005, No. 1)

Differences in Potassium Requirementand Response by Older andModern Cotton VarietiesBy J.J. Camberato and M.A. Jones

Late-season potassium (K) deficiencies have occurred in many South Carolinacotton fields over the past few years, with some varieties showing deficiency symp-toms more frequently than others. Newer, higher-yielding, fast-fruiting cotton variet-ies appear to respond more favorably to applied K than older varieties, and maybenefit from increased application rates.

In recent years, late-season K deficien-cies have been observed in manycotton fields across South Carolina.

Some varieties have appeared to show Kdeficiency symptoms more frequently thanothers. New, higher-yielding, earlier-ma-turing cotton varieties develop more oftheir total boll load over a shorter periodof time, which can lead to a more con-densed boll filling period and an increaseddemand for the uptake and mobilizationof K from the soil and leaf to the develop-ing lint�from 2 to 4 lb K/A/day.

Since K is the primary osmoticum forfiber development and provides the turgorpressure necessary for fiber elongation,optimum cotton yields and fiber qualityare highly dependent upon an adequatesupply of K throughout the growing sea-son. Late-season K deficiencies appear tobe extremely detrimental to cotton, withreduced fiber quality (especially fiberlength, strength, and micronaire) and lintyield, often occurring as a result of late-season K deficiencies.

Excessive drying of the upper soil lay-ers renders K unavailable to the crop, anddeep soil layers have little K because down-ward leaching is limited in relatively highcation exchange capacity soils. Soils in theCoastal Plain region of South Carolina aremuch different than those in the Missis-sippi River Delta, and the distribution and

SOUTH CAROLINA

availability of K are also quite different.Coastal Plain soils typically have accumu-lations of K in clayey subsoil layers due toleaching of K incorporated into sandy sur-face soil layers. The extent of downwardK movement during the growing seasonand access to subsoil K likely governs Kavailability in Coastal Plain soils. CurrentK fertilizer recommendations in SouthCarolina are based on pre-season K levelsof the topsoils that are adjusted by depthand K content of the subsoil. The data es-tablishing the subsoil K adjustment to fer-tilizer recommendations preceded develop-ment of these high K-demanding cottonvarieties. Research was conducted to de-termine if current soil sampling proceduresand recommendations are valid to optimizeyield of modern cotton varieties.

A replicated field experiment was con-ducted in 2002 and 2003 at the Pee DeeResearch and Education Center located inFlorence on a Norfolk-Bonneau soil com-plex (Typic Kandiudult-Arenic Paleudult)identified as K deficient in 2001. The plowlayer, upper 8 in. of the E-horizon, andupper 8 in. of the B-horizon were sampledprior to initiating the experiment andanalyzed for Mehlich-1 K and soil pH.Depth to the B-horizon was also deter-mined. An attempt was made to optimizeyields utilizing a center-pivot irrigationsystem, a split application of 120 lb N/A,

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Better Crops/Vol. 89 (2005, No. 1) 19

and intense pest control.Potassium treatments were broadcast

prior to planting at 0, 50, 75, 100, and 125lb K2O/A. Five cotton varieties releasedbetween the years 1915 and 2001 (DixieTriumph, 1915; DPL 90, 1981; DES 119,1985; Paymaster 1218BR, 1998; and DPL555BR, 2001) were evaluated. The experi-mental design was a split-plot with K fer-tilization rate as the whole plot (20 rowswide by 40 ft. long) and variety as the splitplot (4 rows wide by 40 ft. long).

Only the center two rows were used forplant tissue and lint harvest. Leaf and peti-ole samples were obtained every 2 to 3weeks from first bloom through cutout tomonitor K status of the cotton plant. Thesap from 20 petioles was squeezed out, andK determined with a Cardy K+ meter. Leaftissue was dried, ground, and analyzed fornutrient content by standard laboratoryprocedures. Weekly white bloom countsfrom one middle row were conducted.Destructive plant sampling ( 1 ft. of row)occurred at early squaring (matchheadsquare) and at cutout, in order to deter-mine changes in dry matter partitioning,boll development, and relative maturitylevels. At harvest, plants were mapped toassess changes in fruit distributionthroughout the canopy, and plots weremachine-harvested. Lint yield, gin turn-out, and fiber quality were determined. Re-sponse to K fertilization was examined inrelation to K fertilization rate and inten-sity of the boll-filling period (old to new

varieties) as it is altered by the supply anddistribution of soil K.

Cotton growth and development wassignificantly altered by the K treatments,and visible differences in deficiency symp-toms in the field occurred among varietiesand K rates (Figures 1 and 2). Significantpremature leaf defoliation occurred atlower K application rates, but varied withvariety (Figure 3). Leaf and petiole K lev-els were positively related to the sum ofthe initial soil K level of the A-horizon plus50% of the K fertilization rate (Figures 4and 5). Including E- or B-horizon K levelsand/or a higher or lower percentage of Kfertilization rate did not improve these re-lationships. Leaf K appeared to be a bet-ter indicator of K supply than petiole K,but was also more affected by growth stagecompared to petiole measurements. LeafK concentrations were low throughout boll

FFFFFigurigurigurigurigure 1.e 1.e 1.e 1.e 1. Visual response of cotton variety PM1218BR to 125 lb K

2O/A.

FFFFFigurigurigurigurigure 2.e 2.e 2.e 2.e 2. Visual response of DPL 90 to 125 lbK

2O/A.

FFFFFigurigurigurigurigure 3.e 3.e 3.e 3.e 3. Relationship between premature leafdefoliation and leaf K in July.

0

20

40

60

80

100

120

0.50 1.00 1.50 2.00

July leaf K, %

De

folia

tio

n, %

Defoliation versus leaf K - 2003

PM 1218BRr2= 0.57

DPL 555BRr2= 0.72

DES 119r2= 0.61

DPL 90r2= 0.41

Dixie Triumphr2= 0.64

AAAAAugusugusugusugusugust 12t 12t 12t 12t 120 lb K0 lb K0 lb K0 lb K0 lb K

22222O/AO/AO/AO/AO/AAAAAAugusugusugusugusugust 12t 12t 12t 12t 12

125 lb K125 lb K125 lb K125 lb K125 lb K22222O/AO/AO/AO/AO/A

VVVVVarararararieieieieietytytytyty: PM 1218BR; r: PM 1218BR; r: PM 1218BR; r: PM 1218BR; r: PM 1218BR; released in 1998eleased in 1998eleased in 1998eleased in 1998eleased in 1998

AAAAAugusugusugusugusugust 12t 12t 12t 12t 120 lb K0 lb K0 lb K0 lb K0 lb K

22222O/AO/AO/AO/AO/AAAAAAugusugusugusugusugust 12t 12t 12t 12t 12

125 lb K125 lb K125 lb K125 lb K125 lb K22222O/AO/AO/AO/AO/A

VVVVVarararararieieieieietytytytyty: DPL 90; r: DPL 90; r: DPL 90; r: DPL 90; r: DPL 90; released in 1981eleased in 1981eleased in 1981eleased in 1981eleased in 1981

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20 Better Crops/Vol. 89 (2005, No. 1)

Figure 4. Relationship between percent leaf K andsoil test K levels in the A-horizon plus50% of the applied K rate. Sufficiencyrange is 1.5 to 3.0% K at early bloom to0.75 to 2.5% at late bloom.

0.40.60.81.01.21.41.61.8

25 75 125 175A-horizon soil test K + 50% K rate, lb/A

Le

af

K, %

Aug. 6th

r2= 0.53

July 2nd

r2= 0.78

July 17th

r2= 0.72

1.5% K

0.75% K

Figure 5. Relationship between petiole K and soiltest K levels in the A-horizon plus 50%of the applied K rate.

1,000

2,000

3,000

4,000

5,000

6,000

7,000

25 75 125 175

A-horizon soil test K + 50% K rate, lb/A

Pe

tio

le K

, p

pm

Aug. 6th

r2= 0.50

July 2nd

r2= 0.54

July 17th

r2= 0.68

development (especially with the low Kfertilizer treatments), attaining deficiency

levels of less than 1.5% at early bloom andless than 0.75% at cutout. All varieties re-sponded favorably to increased levels of

leaf K, but the recently released, higher-yielding varieties such as PM 1218BRand DPL 555BR responded more to Kthan older, lower-yielding varietiessuch as Dixie Triumph, DES 119, andDPL 90 (Tables 1 and 2). Lint yields in-creased 400 to 800 lb/A with each 1%increase in leaf K. Yields of newly re-leased varieties increased more thanolder varieties.

Based on these recent results, new,higher-yielding, fast-fruiting cottonvarieties may respond favorably tohigher rates of applied K than oldervarieties. BC

Dr. Camberato (e-mail: [email protected]) andDr. Jones (e-mail: [email protected]) are withClemson University, located at the Pee Dee Re-search and Education Center in Florence, SouthCarolina.PPI/FAR Research Project SC-13F

North Central Extension-Industry Conference Proceedings Available

230-page proceedings (Vol. 20) is US$20.00plus shipping. Contact PPI, 772 22nd Ave.South, Brookings, SD 57006. Phone (605)692-6280, fax (605) 697-7149, or e-mail:[email protected].

Proceedings of the 2004 North CentralExtension-Industry Soil Fertility

Conference are now available for purchase.The annual conference took place Novem-ber 17-18, 2004, in Des Moines. Cost for the

TTTTTable 2.able 2.able 2.able 2.able 2. Variety response to K supply � 2003.Change in

lint yield perLeaf %K (8/6) % change in Lint yield,

Variety with high K leaf K, lb/%K lb/A1

Dixie Triumph 1.18 458 341DPL 90 1.19 428 594DES 119 1.21 718 543PM 1218BR 1.30 528 571DPL 555BR 1.16 819 6431Average across all K rates.

TTTTTable 1.able 1.able 1.able 1.able 1. Variety response to K supply � 2002.Change in

lint yield perLeaf %K (8/6) % change in Lint yield,

Variety with high K leaf K, lb/%K lb/A1

Dixie Triumph 1.02 409 613DPL 90 1.26 497 845DES 119 1.06 666 900PM 1218BR 1.20 543 962DPL 555BR 1.25 678 1,0561Average across all K rates.

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Better Crops/Vol. 89 (2005, No. 1) 21

A new publication from PPI titled Be Your Own Cotton Doctor offers

cotton growers and their advisers and con-sultants a new tool. The 8-page bookletfeatures 40 color illustrations showingtypical symptoms of nutrient deficiencies,toxicities, diseases, and other disorders incotton production. While it does not sub-stitute for diagnostic tools such as planttissue analysis and soil testing, this publi-cation can help distinguish and identifyvarious field problems.

The 8 ½ x 11-in. guide is patternedafter the classic publication Be Your OwnCorn Doctor, which has been widely usedfor over 50 years. Be Your Own CottonDoctor is available for US$0.50 per copy,plus shipping. Discount on quantities.

Contact: Circulation Department,PPI, phone (770) 825-8082; fax (770) 448-0439, or e-mail: [email protected]. BC

Introducing:Be Your Own Cotton Doctor

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22 Better Crops/Vol. 89 (2005, No. 1)

C A L I F O R N I A

The Sustainable Agriculture Researchand Education Program of theUSDA�s Cooperative State Research,

Education, and Extension Service definessustainable agriculture as an agriculturalproduction and distribution system that:

1. Achieves the integration of naturalbiological cycles and controls.

2. Protects and renews soil fertility andthe natural resource base.

3. Optimizes the management and use ofon-farm resources.

4. Reduces use of nonrenewable resourcesand purchased production inputs.

5. Provides an adequate and dependablefarm income.

6. Promotes opportunity in family farm-ing and farm communities.

7. Minimizes adverse impacts on health,safety, wildlife, water quality, and theenvironment.The objectives of sustainable agricul-

ture programs are admirable and each ofthe points listed above expresses a veryworthy objective. Being against sustain-able agricultural as expressed in these ob-jectives is akin to being against mother-hood and apple pie. However, we have tobe careful in our enthusiasm for the objec-tives of sustainable agriculture that wedon�t encourage a backlash against agri-culture in general, that is harmful to thefood distribution system and human nu-trition. Some enthusiastic supporters ofsustainable agriculture are creating animage of agriculture as it is currently

conducted in the U.S. as a �nonsustainableagriculture�. Creation of artificial bound-aries between us (strong adherents of sus-tainable agriculture objectives) and them(other people who do agriculture) is notconducive to progress in meeting the goalsof sustainable agriculture.

The fact that we defined some desir-able objectives and loosely encompassedthem under the term �sustainable� agri-culture should not suggest that our cur-rent agricultural system in the U.S. isunacceptable, antiquated, or evil. Ameri-can agriculture, while far from perfect, isproductive, evolving ecologically, and re-mains an important breadbasket to theworld. Agriculture within the confines ofthe U.S., and even more so in many west-ern European countries where populationgrowth is negative, becomes more sustain-able every year.

We do not want to get into playingthe game of who is more sustainable thanwhom. While a sustainable agriculture isessential for maintaining long-term humanexistence, problems with its establishmentare in the details. Putting full effort intomeeting one of the objectives of sustain-able agriculture may infringe negatively onone of the other objectives. For example,the development of the tomato harvestermaximized the use of on-farm resources(such as capital) and improved farmincome for some tomato-growing farmfamilies while at the same time reducedemployment opportunities for others who

What Is Sustainable Agricultureand How Do We Do It?By Craig Kallsen

�Sustainable agriculture� should not be considered a separate system from thecurrent production agriculture system in the U.S. Artificial boundaries will not beconducive to meeting the goals of sustainable agriculture or to meeting the chal-lenges of providing food, fiber, and fuel needed by the world�s growing population.

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Better Crops/Vol. 89 (2005, No. 1) 23

depended on hand-picking for their liveli-hood. Which uses less non-renewable en-ergy�a single tomato picking machine, or60 people driving to the farm to harvesttomatoes by hand? Who decides what isan adequate and dependable farm income?The objectives of sustainable agricultureare not as straightforward as they appearand conducting a more sustainable agricul-ture is just as much of a balancing actamong environmental, economic, and so-cial issues as is any other human enterprise.

Many of the success stories describedfor programs supporting sustainable agri-culture describe small family farm enter-prises. Typically these families have founda niche that is vertically integrated in thatthey both produce food or fiber and take amore active role in marketing it. Often theyreceive a price premium for their producebecause it was grown organically withnatural pesticides and fertilizers or, at least,with reduced levels of synthetic pesticidesand fertilizers. While these enterprises areadmirable, there is no way that everyonewho desires to make a living from agricul-ture can survive economically doing this.If too many people get in the niche, it ei-ther is no longer a niche, or it is overlycrowded and somebody is no longer goingto have an adequate or dependable income.

Large corporate farms are often ac-cused of being contrary to the objectivesof most if not all of the goals of sustain-able agriculture. In fact, some of the mostinnovative and environmentally friendlyfarming practices are being conducted bylarge farming operations in the SanJoaquin Valley of California. These prac-tices include integrated pest management,water protection and storage, the creationof good paying jobs with reduced drudg-ery and with reduced potential for repeti-tive work injuries, and the use of more en-ergy efficient machinery that comes withtaking advantage of scale.

There is a potential danger of havingan agriculture that gets too far out aheadof the rest of American society and theworld in sustainability. For example, theworld�s current use of oil is not sustain-

able. Oil reserves are down and world stock-piles of agricultural commodities are thelowest they have been for years. The fore-cast increase in world population is notsustainable. World agriculture, sustainableor not, must sustain the world�s popula-tion growth, sustainable or not. SomehowAmerican agriculture will have to help sup-port the huge population growth forecastfor many of the world�s developing coun-tries. To feed the world�s burgeoning popu-lation over the next 50 years or so, we needthe ability to harness the productivity ofsynthetic fertilizers, pesticides, andgroundwater supplies, even if the use isnonsustainable. Sustainability, and thehealth of the world environment, mayhave to be compromised to some extent inthe short-term, if people are to be fed inthe next few decades. Agriculture is just apiece, albeit an important piece, of soci-ety. For sustainability to occur in agricul-ture, society, as a whole, must use its re-sources of air, water, land, energy, and allelse in a more sustainable way.

To insist that farmers in the U.S. be-come fully sustainable immediately, whenfarmers in the rest of the world are not,puts American farmers at a real and dis-tinct economic disadvantage. Sustainableagricultural objectives should be guidelinesfor all of agriculture. To try to make theseguidelines into a separate farming systemor a philosophy of life is to unduly com-plicate the already fragile balance thatfeeds the world and keeps food affordable.

Sustainable agricultural programshave rediscovered and increased the knowl-edge base of practices that farmers usedto maintain their productivity before theadvent of the 20th century. The safest,most secure, and prudent changes thatagriculture accomplishes toward greatersustainability occur from within theagriculture system, one producer at atime, and not from attempts to force pre-mature and possibly catastrophic changesen masse from the outside. BC

Mr. Kallsen is Farm Advisor, University ofCalifornia Cooperative Extension, Bakersfield;e-mail: [email protected].

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24 Better Crops/Vol. 89 (2005, No. 1)

Nutrient Exclusivity in Organic Farming�Does It Offer Advantages?By H. Kirchmann and M.H. Ryan

The following aims are associated with organic farming: to produce healthier foods,to be environmentally friendly, and to be more sustainable. Organic principles areapplied in the belief that they are the best way to achieve these aims. However, acritical analysis of organic fertilization practices does not support this belief.

Fertilization within organic farmingis designed to maintain soil fertility,but not to directly feed plants. Nu-

trients are applied in organic or low solu-bility inorganic forms in the belief thatplants will obtain balanced nutritionthrough the actions of soil microbes. Theexclusion of synthetic fertilizers in organicfarming has been motivated by various ar-guments: lower crop quality, faster humus-breakdown, and a non-synchronized sup-ply to crops. Furthermore, philosophicalviews about life are a basic fundament fororganic principles (Kirchmann 1994).

What yields are achieved on organicfarms and what area of land is requiredto sustain these yields?

A number of long-term field trials inEurope reveal that crop yields are on aver-age 20% lower in organic systems thatcombine crops with animals and 33 to 45%lower in organic systems with crops alone,compared to their conventional counter-parts (Table 1). Studies of farms underlong-term organic management in Austra-lia reveal yields of individual crops as sub-stantially lower than on conventionalneighboring farms (Table 1). Lower yieldsreflect either a lower fertilizer input and/or a lower uptake efficiency of nutrientsfrom fertilizers.

The low yields on organic farms meanthat to produce the same amount of foodas conventional farms, more land isneeded. For instance, to sustain food pro-

duction in Europe, widespread adoption oforganic farming without animals wouldrequire an increase in land area of 64%,assuming crop production is reduced by39%, and adoption of organic systemswith animals would require an increase inland area of 25%. If conventional farm-ing is widely replaced by organic farming,clearing of wildlife habitats and conversionof natural and semi-natural ecosystemsinto agricultural land is unavoidable in sys-tems that did not originally produce a foodsurplus. Thus, biodiversity will be reduced.But the main concern is that lower yieldswould increase the size of the world hun-ger map.

Can an enhanced soil biological commu-nity improve availability of plantnutrients in organic systems?

It is often assumed that the soil bio-logical community will be enhanced in re-sponse to organic management, develop-ing a greater capacity to supply plants withnutrients from organic and poorly solubleinorganic sources. One component of thesoil biological community that occur con-sistently more abundantly on organicfarms are arbuscular mycorrhizal fungi, assoluble phosphorus (P) fertilizers suppresstheir occurrence on conventional farms(Ryan et al., 2000). Arbuscular mycor-rhizal fungi are best known for their abil-ity to enhance host plant uptake of P andother nutrients. However, studies of or-ganic crops and pastures in southern

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Better Crops/Vol. 89 (2005, No. 1) 25

Australia show that high colonization doesnot overcome the serious P-deficiency ex-perienced in these systems (Ryan et al.,2000; Ryan and Angus, 2003). Indeed, asthe fungi obtain all carbon (C) require-ments from the host plant, if the fungisupply no return nutritional benefits theymay act as a parasite on crops, reducingcrop yield potential (Ryan et al., in press).The generalization that organic practicesautomatically stimulate an enlarged soilbiological community, and that this canpartly substitute for inorganic fertilizers,is inaccurate (Ryan and Ash, 1999).

Lower mean N input in organicfarming�does it result in less nitrateleaching?

A comprehensive literature reviewshowed that the average leaching of nitrate(NO3) over a crop rotation was somewhatlower per unit area from organic systemsthan conventional systems (Kirchmannand Bergström, 2001). However, a correctcomparison of leaching between systemsalso requires yields to be considered andthis was not accomplished due to differ-ences in the sequence and type of cropsgrown, differences in the input intensity

TTTTTable 1.able 1.able 1.able 1.able 1. Mean yields and N inputs from long-term farming system experiments in Europe and frompaired commercial farms under long-term organic and conventional management in Australia.

Yield, Yield N input,Experiment and t/ha decrease, kg/ha/yrfarming system Organic Con. % Organic Con. Reference

Norway: Apelsvoll-siteNorway: Apelsvoll-siteNorway: Apelsvoll-siteNorway: Apelsvoll-siteNorway: Apelsvoll-site (8 years)(8 years)(8 years)(8 years)(8 years)Crops plus animals 121 227 Korsaeth and Eltun , 2000Barley, oats, wheat 3.7 5.0 26 Eltun et al., 2002Three-year forage crop 8.3 10.7 22Green fodder 7.1 7.6 7

SwitzerSwitzerSwitzerSwitzerSwitzerland: DOKland: DOKland: DOKland: DOKland: DOK-tr-tr-tr-tr-trials (24 yials (24 yials (24 yials (24 yials (24 yearearearearears )s )s )s )s )Crops plus animals 105 138 Spiess et al., 1993Winter wheat 4.1 4.5 10 Besson et al., 1999Three-year forage crop 11.5 14.0 18 Mäder et al., 2002Potato 30.0 48.0 38

SwSwSwSwSweden: Skeden: Skeden: Skeden: Skeden: Skåne-tråne-tråne-tråne-tråne-trials (12 yials (12 yials (12 yials (12 yials (12 yearearearearears)s)s)s)s)Crops only 59 130 Ivarson and Gunnarsson,Winter wheat 3.7 6.3 41 2001Potato 21.4 38.0 44Crops plus animals 110 185Winter wheat 4.1 6.4 36Two-year forage crop 6.6 9.3 29

AAAAAususususustrtrtrtrtralia: Nalia: Nalia: Nalia: Nalia: Neeeeew Soutw Soutw Soutw Soutw South Wh Wh Wh Wh Wales (30 yales (30 yales (30 yales (30 yales (30 yearearearearears; One pair of fs; One pair of fs; One pair of fs; One pair of fs; One pair of farararararms )ms )ms )ms )ms )Crops plus animals 0 173 Ryan et al., 2004Wheat1 2.9 5.5 48

AAAAAususususustrtrtrtrtralia: Valia: Valia: Valia: Valia: Victictictictictorororororia (17 yia (17 yia (17 yia (17 yia (17 yearearearearears; 10 pairs; 10 pairs; 10 pairs; 10 pairs; 10 pairs of fs of fs of fs of fs of farararararms)ms)ms)ms)ms)Animals only 0 173 Small and McDonald, 1993Milk , L/ha/year2 6740 9060 261 Organic wheat was fertilized with 18 kg P/ha/year as rock phosphate and conventional wheat with 16 kg P/ha/year asdiammonium phosphate (average grain yields over 3 years from a farm pair where one farm had been under organicmanagement for 30 years).2 Conventional pastures received 27 kg P/ha/year as soluble synthetic fertilizers, while biodynamic pastures received no P(average milk yields over 3 years from 10 paired farms where one farm in each pair had been under biodynamicmanagement for an average of 17 years).3 N directly applied in fertilizer (N inputs from legumes not calculated).

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26 Better Crops/Vol. 89 (2005, No. 1)

of nitrogen (N) and a general lack of yielddata (Kirchmann and Bergström, 2001). Ina series of Swedish long-term field lysim-eter trials that commenced in the early1990s, similar crop rotations in the organicand conventional system were maintained,except in years when green manure wasgrown. Furthermore, mean N input in theorganic systems was close to that of con-ventional systems (Table 2). In these stud-ies, on both a sandy and a clay soil, organicsystems had greater nutrient leaching andgreater release of N and P to drainagewater both per hectare and per unit ofharvested N. These experiments indicatethat if differences between comparativestudies caused by different crop rotationsand N input intensity are largely elimi-nated, leaching of N from organic systemsis not lower per unit area.

It appears that the asynchrony of cropN demand and N release from manurescompared to inorganic synthetic fertilizersis the major cause for the higher leachinglosses from organic systems, as more ma-nure N remains in the soil after applica-tion and is mineralized at times when thereis no crop demand (Bergström andKirchmann, 1999; 2004).

Is nutrient cycling enhanced by organicfarming?

There is no doubt that thesustainability of most agriculturalsystems could be improved through an in-creased emphasis on recycling and greaterreturn of nutrients in municipal wastes andoff-farm products. However, losses via the

food cycle would not be reduced throughwidespread adoption of organic farming ascurrent regulations within the organicmovement do not allow use of urbanwastes due to concerns about contamina-tion with metals and organic pollutants.To improve recycling of nutrients and re-duce the risk of contamination with pol-lutants, new recovery technologies to ex-tract nutrients out of wastewater andbiogas residues and other municipal wastesare currently being developed. However, asthe new nutrient recovery technologies willproduce easily soluble, inorganic products,only conventional farmers may be able touse these products and thereby improve nu-trient cycling.

To maintain soil fertility, organic farm-ers may purchase approved organic fertil-izers. In Europe, these fertilizers generallyoriginate from conventional production. Infact, in Sweden there is an increasing trendin organic farming to apply nutrients ofoff-farm origin via approved organic fer-tilizers such as meat meal, bone meal, poul-try manure, and wastes derived from foodindustries (Swedish Control Organizationfor Alternative Crop production). This isan indirect transfer of nutrients originat-ing from conventional production andcreates a reliance on production systemsfertilized with inorganic fertilizers. A regu-lation by the European Union (EU) willprohibit the use of conventionally grownfodder in organic animal production afterAugust 2005. On the other hand, there arepractically no restrictions on the use oforganic fertilizers, such as animal manures,

TTTTTable 2.able 2.able 2.able 2.able 2. Partial N budget in organic and conventional long-term trials in Sweden.Experiment and Organic Conventionalfarming system Input Offtake Leaching Input Offtake Leaching

- - - - - - - kg N/ha/yr - - - - - - - - - - - - - - kg N/ha/yr - - - - - - - Reference

Halland-sitHalland-sitHalland-sitHalland-sitHalland-siteeeeeCrops only 66 30 43 99 79 29 Torstensson et al., 2005Crops plus animals 120 105 35 113 71 26

VäsVäsVäsVäsVästttttererererergggggööööötland-sittland-sittland-sittland-sittland-siteeeeeCrops only 105 42 20 113 85 3 Torstensson, 2003a

Lindén et al., 1993MeanMeanMeanMeanMean 9797979797 5959595959 3333333333 108108108108108 7878787878 1919191919

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Better Crops/Vol. 89 (2005, No. 1) 27

derived from conventional farms and onby-products from food processing indus-tries (meat meal, blood meal, bone meal,residues from fish industries, canning in-dustries etc). Thus, organic farmers cancontinue to rely on the import of nutrientsfrom conventional production throughpurchase of organic manures. This ap-proach obviously would not be sustainableif a large proportion of farms convert toorganic production.

Several peer-reviewed papers concludethat organic farming is superior toconventional agriculture.How stringent are comparisons?

There is a tendency when presentingresults from comparative studies of organicand conventional farms to assume that anydifferences occurring between systems area consequence of the management factorsthat are inherently dissimilar, namely theexclusion of pesticides and readily solubleinorganic fertilizers on organic farms.Thus, it is assumed that the results are gen-erally representative of organic and con-ventional systems. However, differencesmay be caused by management practicesthat are potentially open to manipulationin a similar manner in each system and/ormay vary greatly within one or both.

The following factors should be consid-ered when evaluating comparative studiesof systems:

1) The soil fertility status at the start ofan experiment will determine the pro-ductivity of the system. In fertile soils,initially, smaller yield differences willbe detected and both fertilizer and en-ergy efficiency will be in favor of low-input systems.

2) The choice of crops in rotation will de-termine N leaching. Crops affect N

leaching from agricultural soils in sev-eral ways: the longevity of the crop,rooting depth, the amount of cropresidues and their mineralization po-tential and the degree of soil tillage.

3) The amount of imported (purchased)nutrients and organic matter need tobe equal. To set aside boundary con-ditions between systems is not scien-tific proof for the superiority of onesystem over the other.

ConclusionWhen critical scientific analysis is ap-

plied to organic farming, the dogma of su-periority of organic farming fails. Despitetheir aim of being more sustainable, or-ganic principles do not provide a betterlong-term outcome in the search for suffi-cient food production than conventionalones. We advocate a flexible approachwhere farming systems are designed tomeet specific environmental, economic,and social goals, unencumbered by unsci-entific, dogmatic constraints (Kirchmannand Thorvaldsson, 2000). BC

Dr. Kirchmann is Professor in Plant Nutrition andSoil Fertility at the Swedish University of Agricul-tural Sciences, Department of Soil Sciences, Box7014, S-750 07 Uppsala, Sweden; e-mail:[email protected].

Dr. Ryan is Lecturer at the School of PlantBiology, The University of Western AustraliaMO81, Crawley, WA, Australia, 6009; [email protected].

References: Due to space limitations, thereference list is not printed in the originalissue. The reference list is available as aPDF file (with the article) at the website:>www.ppi-ppic.org<.

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28 Better Crops/Vol. 89 (2005, No. 1)

1/04

Soil Testing:A Proven Diagnostic ToolBy Sam Portch and Mark D. Stauffer

Soil testing is being under-utilized in the developing world, but datashow it puts money in farmers� pockets even when the relatively highcost of a complete analysis is considered. Developing the system totruly meet a farmer�s needs is both practical and feasible.

It is difficult to determine who exactly began the science of soil test-ing. Certainly, Europeans such as Justin von Liebig, famed for theLaw of the Minimum, and Jean Baptiste Boussingault, sometimes

referred to as the father of modern agricultural chemistry, would be can-didates as founding fathers. Since then, several scientists during the late1920s and early 1930s, including those well known by their analyticalmethods such as Bray, Morgan, Spurway, and Truog, advanced soil test-ing by showing the importance of measuring labile or available ratherthan total plant nutrient contents. In terms of service, one of the earli-est laboratories established to analyze large numbers of farmers’ sampleswas developed in the early 1940s by J.W. Fitts in Nebraska.

Today, around 4 to 5 million (M) soil samples are analyzed annuallyin North America alone, in both private and state operated facilities.While this is an impressive number, it still falls short of being adequatefor the region’s large cultivated area. If one looks outside North America,it is clear that soil testing is even more underutilized as a diagnostic tool.The most frequently noted reasons are discussed within this article alongwith points to consider for improving its application.

Common PitfallsCommon PitfallsCommon PitfallsCommon PitfallsCommon PitfallsThe first issue is that many laboratories throughout the world rou-

tinely offer an incomplete assessment of soil fertility, providing only ananalysis of pH, organic matter, some form of ni-trogen (N), available phosphorus (P), and potas-sium (K). Data from China (TTTTTable 1able 1able 1able 1able 1) illustrate thisproblem as the prevalence of secondary and mi-cronutrient deficiencies in a number of soils obvi-ously means that a large percentage of soils werenot receiving adequate analyses—at least 49% ifone considers only zinc (Zn). But given the rangeof deficiencies, at least 70 to 80% of these soilswere inadequately assessed until a complete analy-sis was done. Unfortunately, the same can be saidfor research results based on incomplete soilanalysis. Based on TTTTTable 1able 1able 1able 1able 1, greater than 50% of

Soil tSoil tSoil tSoil tSoil tesesesesestingtingtingtingting atBathalagoda ResearchStation in Sri Lanka showedthe need for K fertilizer.Application of K fertilizerresulted in 1 t averageyield response over threeconsecutive rice crops.

International SectionThe Government of Saskatchewan helps make the International Section of this publication possible throughits resource tax funding. We thank them for their support of this important educational project.

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research using onlyN, P, and K analyseswould give mislead-ing, lower than opti-mum yield results.

I n c o m p l e t eanalyses lead to thenext reason for un-der-utilization ofsoil testing—thatbeing populariza-tion of generalized,generalized,generalized,generalized,generalized,low yielding ferlow yielding ferlow yielding ferlow yielding ferlow yielding fertilizer rtilizer rtilizer rtilizer rtilizer recommendationsecommendationsecommendationsecommendationsecommendations. Continued mischaracterizationof soil fertility status sets up a feedback loop wherein researchers canonly obtain misleading, suboptimal results. The failure of researchers toscrutinize their individual trials sufficiently results in the pooling of poordata with good data. Setting reasonably high yield goals for each trialcould help researchers distinguish between good and poor data. Low yield-ing trials should undergo further study to determine why they performedpoorly. If the trial had excessive insect dam-age, incorrect analysis, poor weather or man-agement, etc., the data should not be pooledwith other valid data. Thirdly, years of researchand observations by the authors, particularlyin developing countries, has led to the conclu-sion that conservative recommendations—tohelp the farmer reduce his fertilizer costs—of-ten reduce his income substantially by ineffi-cient utilization of all inputs, including fertil-izers. Little or no thought is given to theopportunity cost of under-utilized yield poten-tial.

Slow serSlow serSlow serSlow serSlow servicevicevicevicevice is probably the worst deterrent preventing farmer useof soil testing services. Returning fertilizer recommendations to a farmerlong after samples were taken from the field minimizes the benefit, giv-ing the entire concept of soil testing a bad reputation. Recommenda-tions have little meaning to the farmer if the crop for which they wererequired is already planted (although the soil test results are useful forfuture nutrient management). Slow service is most apparent in develop-ing countries where a turn-around time of less than one month is excep-tional. In countries where two or three crops are grown per year, fasterservice is essential. A maximum of 7 to 10 days would be acceptable;anything longer detracts from the service.

The last common concerThe last common concerThe last common concerThe last common concerThe last common concern is cost of the sern is cost of the sern is cost of the sern is cost of the sern is cost of the servicevicevicevicevice. Subjecting a soilsample to a ‘complete’ analysis involves 12 to 14 determinations and cal-culations. The cost of this varies from country to country, but an indi-vidual sample would cost between US$12 to US$20, including the reportwith recommendations. This is often out of range for many resource-

Three reasons why many generalizedfertilizer recommendations result in lowyields:

a ) Many misleading research results haveguided researchers this way;

b ) Pooling of poor data with good;c) An inherent feeling that conservative

recommendations save farmers moneyby reducing fertilizer input costs with-out looking at lost profit.

TTTTTable 1.able 1.able 1.able 1.able 1. Results of 140 greenhouse trials based on soil analyses with soils from 17provinces of China (relative dry yield matter with optimum [OPT] as 100 %).

Nutrient omitted # soils showing deficiency, Range of Averagefrom OPT % of total 140 relative yield, % relative yield, %

-N 137 (98%) 6.1 to 83.9 45.2-P 126 (90%) 8.5 to 89.7 39.6-K 84 (60%) 39.0 to 89.8 73.5

-Ca 20 (14%) 2.2 to89.0 52.8-Mg 25 (18%) 34 to 89.7 74.7-S 45 (32%) 14.0 to 89.8 71.3-Fe 17 (12%) 46 to 87.5 79.4-B 36 (26%) 65 to 89.7 80.9

-Cu 37 (26%) 40 to 89.5 77.2-Mn 34 (24%) 50.2 to 89.5 79.1-Mo 28 (20%) 38.7 to 89.4 79.5-Zn 68 (49%) 40.0 to 89.6 75.1

A R G E N T I N A

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30 Better Crops/Vol. 89 (2005, No. 1)

poor farmers, especially those managing a frac-tion of a hectare. The burden to the farmer couldhopefully be lessened through either analyzing alarger volume of soils, thereby reducing the costper sample or by subsidy made available by gov-ernment or the ag retailer as part of a customerservice package. In the case of small holders, onesuccessful compromise has been to encourage ad-

joining farmers to consolidate their fields and develop a shared recom-mendation of fields with similar landscape, soil type, crop, management,and yield goals. Farmer cooperatives might develop a seasonal field sam-pling rotation that produces a common recommendation for a small num-ber of fields. Thus, analysis cost can be spread amongst a large numberof farmers, but still have an applicable area.

Some may say soil testing is not a worthwhile endeavor, particularlyin developing countries. However, the potential benefits from more de-finitive research results and recommendations require that one must lookfor ways to develop sound soil testing systems. How could this be done?

The first goal should be incrThe first goal should be incrThe first goal should be incrThe first goal should be incrThe first goal should be increased awareased awareased awareased awareased awareness eness eness eness eness (from administrationto technician-level) about the problems mentioned. Strategies to over-come these problems will no doubt follow. The main objective is to regardsoil testing as more than just the ‘bricks and mortar’ of a laboratory. Acomplete program provides: sampling and sample handling, the labora-tory, local research and data interpretation, dynamic recommendations,plus education and extension in all the above.

Benefits frBenefits frBenefits frBenefits frBenefits from an Optimized Soil Tom an Optimized Soil Tom an Optimized Soil Tom an Optimized Soil Tom an Optimized Soil Testing Seresting Seresting Seresting Seresting ServiceviceviceviceviceWhere reliable soil testing is being used, many successful and profit-

able research- and farmer-oriented results are produced. One of the mostrecent and convincing examples comes out of the Bathalagoda rice re-search station in Sri Lanka. Prior to intervention, six consecutive sea-sons of N, P, and K research on rice failed to show any need for K fertil-izer. Secondary and micronutrient deficiencies were not being addressed,hence, only low yields were obtained. After a complete soil test, magne-sium (Mg), sulfur (S), boron (B), and copper (Cu) were included in alltreatments along with variable rates of N, P, and K. The result was a1 tonne (t) average yield response to K over three consecutive rice crops.Seasonal yields ranged between 5.3 and 6.2 t/ha when all yield-limitingnutrients were applied. Higher yields are almost certainly possible usingthis knowledge to adjust other agronomic practices.

Many observations in India show higher, more profitable yields whenfertilizer programs are based on complete soil analyses. Data often illus-trate that recommendations made by many of the state scientists are tooconservative. In northern India, highly significant yield increases in pea(450 kg/ha) and chickpea (1,390 kg/ha) were obtained when soil test-basedtreatments were compared to generalized state recommendations (TTTTTableableableableable22222). Significant responses to P and K were obtained with both crops (datanot shown) and, in both crops, further additions of S and Zn greatlyincreased yield over treatments supplying only N, P, and K. The

In TIn TIn TIn TIn Tibeibeibeibeibet,t,t,t,t, the balancedfertilization plot (at left)showed great response forbarley compared to thelocal recommendedpractice (at right).

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Better Crops/Vol. 89 (2005, No. 1) 31

influence of manganese (Mn)and B (data not shown) were alsopositive in both cases, but onlystatistically significant in thepea crop.

Farmers at five locations ineastern India used soil test-based fertilizer recommenda-tions to produce more profitablerice crops (TTTTTable 3able 3able 3able 3able 3). Interest-ingly, the average loss was lesswhen farmers used their own fer-tilizer program instead of thestate recommendation, but bothwere far less profitable than soiltest-based recommendations.

In the highlands of Tibet, research trials withbarley and wheat showed significantly higher yieldsusing soil test-based recommendations compared withpresent farmer practice. Yield increases were 1,733 kg/ha with barley and 493 kg/ha with wheat. These gainsprovided extra farmer profit of US$313 andUS$83/ha, respectively. Two unreplicated demonstra-tion trials with the same crops in nearby locationsproduced similar results.

Throughout Asia, networks of unreplicated,multi-located field demonstrations provide an effec-tive means of showing farmers that soil test-based rec-ommendations are more profitable than either staterecommendations or their own current practices. Most results remain un-published despite their influence on common practice. For example, theaverage cost of fertilizer for the soil test-based treatment for mustard ineastern India was US$84/ha…higher than the state recommendation(US$43/ha) or the farmer practice (US$59/ha)…but the increased profitresulting from its application was US$183 over the state recommenda-tion and US$149 over the farmer practice (TTTTTable 4able 4able 4able 4able 4). Conservative recom-mendations clearly do not help farmer profitability.

Results from two pomelo demonstration trials in the Fujian Prov-ince of China showed soil test-based yields averaged 7 t/ha over the cur-rent farmer practice and was US$870/ha more profitable. In two bananademonstration trials in the sameprovince, an average increasedprofit of US$540/ha was obtainedusing the soil test-based recom-mendations compared with currentfarmer practice. Similar compari-sons with citrus at three locationsin Hubei Province increased farmer

TTTTTable 2.able 2.able 2.able 2.able 2. The effect of different fertilizer treatments on selectedtreatments in trials with pea and chickpea in northern India.

Grain yield, Straw yield,Crop Treatment kg/ha kg/ha

Pea N30

P90

K90

S40

Zn20

Mn10

B5

3,200 4,470State recommendation 2,750 3,870

N30

P90

K90

S0 Zn

20 Mn

10 B

52,900 4,000

N30

P90

K90

S40

Zn0 Mn

10 B

52,920 4,020

N30

P90

K90

S40

Zn20

Mn0 B

53,000 4,170

C.D. 5% 137 182Chickpea N

30 P

90 K

90 S

40 Zn

20 Mn

10 B

53,390 4,770

State recommendation 2,000 2,800N

30 P

90 K

90 S

0 Zn

20 Mn

10 B

52,800 3,930

N30

P90

K90

S40

Zn0 Mn

10 B

52,900 4,100

N30

P90

K90

S40

Zn20

Mn0 B

53,180 4,450

C.D. 5% 463 653

C.D.=Critical difference

TTTTTable 3.able 3.able 3.able 3.able 3. Loss of profit (US$) growing ricewhen state recommendations (SR)and farmer�s practice (FP) werecompared with soil test-basedfertilizer recommendations ineastern India.

Location Loss with SR Loss with FP

1 -57.70 -53.152 -54.20 -3 -65.40 -52.254 -55.75 -69.505 -47.00 -37.20

Average -56.00 -53.00

TTTTTable 4.able 4.able 4.able 4.able 4. Mean values of fertilizer costs and farmer profit compar-ing soil test (ST) based recommendations with staterecommendations (SR) and farmer practice (FP) in five fielddemonstrations with mustard in eastern India.

Cost of fertilizer, US$/ha Profit, US$/haST SR FP ST over SR ST over FP

Mean values 83.80 41.70 59.00 183.00 149.10

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32 Better Crops/Vol. 89 (2005, No. 1)

profit by an average US$360/ha. Many provinces in China, states in India, andother countries of Asia need to revise their fertilizer recommendations basedon complete soil testing information.

SummarSummarSummarSummarSummaryyyyyConsidering data in this article are derived from research and demon-

stration trials conducted in temperate to tropical conditions with a widevariety of crops, it should be apparent that soil testing, when done cor-rectly, is key to judicious fertilizer use and maximum economic yield.However, useful results are obtained only when the whole soil testingprogram operates at a high level of speed, control, and precision whileperforming a complete analysis.

Testing soil has a cost. However, this should be considered as part ofthe cost of production of a crop or cropping sequence. If done for theexamples used in this article, even using the higher estimate for analysiscost, all results still remain quite profitable for the farmer. Consideringone soil test may be useful for two or three seasons...depending on thecropping pattern...the value of the recommendation will increase as thecost of analysis can be spread over several crops. In perennial crops, ben-efits from proper soil and plant analysis can be realized over several years,making the investment both minimal and wise.

There is also a hidden benefit to soil testing. Following soil test-basedrecommendations usually improves fertilizer use efficiency, meaning moreof the applied fertilizer is taken up by the growing crop to produce higheryields. Higher yields also produce more organic matter to be returned tothe soil, while losses of applied N to the environment are reduced, whichis important for water and air quality. Considering all its benefits, cor-rect soil testing should be vigorously promoted and utilized throughoutthe agricultural world. BC

Dr. Portch is former PPIC Vice President (retired), PPI/PPIC China and IndiaPrograms.

Dr. Stauffer is former PPI/PPIC International Programs Coordinator, PPIC President,and PPI Senior Vice President (retired).

AcknowledgmentsAcknowledgmentsAcknowledgmentsAcknowledgmentsAcknowledgmentsThe authors wish to sincerely thank Drs. K.N. Tiwari, Kaushik Majumdar, Chen Fang,

Tu Shihua, and Darshani Kumaragamage, as well as their cooperators who provided thePPI/PPIC funded data cited in this article.

Soil analyses (Sam Portch and Arvel Hunter, 2002) were provided by the ChineseAcademy of Agricultural Sciences (CAAS)/PPIC laboratory located in Beijing and AgroServices International in Florida, USA.

ReferReferReferReferReferenceenceenceenceencePortch, Sam, and Arvel Hunter. 2002. A Systematic Approach to Soil Fertility Evaluation

and Improvement. PPI/PPIC China Program Special Pub. No. 5.

Note: The publication A Systematic Approach to Soil Fertility Evaluation and Improvementis available on request. Contact the PPIC office in Saskatoon, Saskatchewan; telephone (306)652-3535, fax (306) 664-8941, e-mail: [email protected].

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Fertilizers to Sustain Production of100 Million Metric Tons of GrainBy F.O. García, G. Oliverio, F. Segovia, and G. López

Argentina is anticipating a large increase in its grain production po-tential. It is clear that improved soil nutrient balance is a key to sus-taining this goal.

Sustainable productivity in our agricultural ecosystems is animportant objective for the 21st century. Sufficient attention to cropand soil management details such as control of weeds, insects,

diseases, and soil erosion, along with adequate crop rotation, soil organicmatter balance, and nutrient supply are critical components ofsustainability. Adequate crop nutrient supply is possible only in soils ofoptimum fertility. Most of the grain production regions of Argentina...thePampas and the extra-Pampas areas...were developed under high nativesoil fertility. However, negative soil nutrient balances (nutrient removalexceeding nutrient application) during 100 years of cropping history haveresulted in general deterioration of fertility levels (Andriulo et al., 1996;García, 2001). Sustained, high yield agricultural production can be as-sured once these negative balances are addressed. Crop fertilization isthe main tool available.

Nitrogen (N), phosphorus (P), and in recent years, sulfur (S) are thenutrients of most concern in the Pampas and other grain-production re-gions. Deficiencies and responses to other nutrients such as potassium(K), magnesium (Mg), and micronutrients are reported for specific cropsand areas. Grain production in Argentina, especially for soybeans, hassharply increased in the last decade (FigurFigurFigurFigurFigure 1e 1e 1e 1e 1). A report from FundaciónProducir Conservando has projected a potential production of 100 mil-lion metric tons (M t) of grain for 2010/11 (Oliverio and López, 2002).This increase is projected from further expansion of planted area as wellas average yield improvements for the major grain crops.

This article summarizes and discusses the results of a subsequentprojection by Fundación Producir Conservando (Olivero et al., 2004),which estimates fertilizer consumption based on improved soil nutrientbalances for the goal of 100 M t grain production. The full report is avail-able at >www.producirconservando.org.ar<.

Fertilizer consumption in Argentina has steadily increased since theearly 1990s at a rate of 146,000 t/year (FigurFigurFigurFigurFigure 2e 2e 2e 2e 2). Despite this trend, theoverall nutrient balance is still very negative (FigurFigurFigurFigurFigure 3ae 3ae 3ae 3ae 3a). In the fourmajor grain crops, removal to application ratios for N, P, K, and S areheavily weighted toward depletion at: 3 to 5, 2 to 2.5, 50 to 100, and 10 to100, respectively. The 2010/11 projection by Olivero et al. considers a setof improved rates of replenishment for soil N, P, and S removed bysoybean, wheat, corn, and sunflower. These replenishment rates were es-tablished for each county, or department, according to present soil nutri-ent availability. In highly fertile soils, the replenishment rates were usu-ally lower than 100%, allowing for a decrease in soil nutrient availability

ARGENTINA

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34 Better Crops/Vol. 89 (2005, No. 1)

from a negative nutrient balance. In all cases, crop- and county-specificreplenishment rates were set higher than current estimates. Phosphorusreplenishment rates were set above 100% for wheat and corn in order toaccount for P removed by double-cropped soybeans, a portion of the ro-tation that traditionally relies on residual soil P.

TTTTTable 1able 1able 1able 1able 1 provides site-specific examples of the nutrient replenishmentrates used in the projection. TTTTTable 2able 2able 2able 2able 2 shows national averages for maingrain crops in 2002/03 and those projected for 2010/11.

As a result of the projections, total fertilizer consumption estimatedat 2.3 M t in 2003 would increase by 120% to almost 5.1 M t by 2011.Cereal and oil crops would account for 4 M t, whereas other crops (fruits,vegetables, forages, and others) would account for 1.1 M t. The estima-tion by Olivero et al. considered only increases for N, P, and S. Thus, if

FFFFFigurigurigurigurigure1.e1.e1.e1.e1. Evolution of corn, wheat, soybean, andsunflower production in Argentina, 1991-2003. Source: SAGPyA.

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

9192

9394

9596

9798

9900

0102

03

Gra

in p

rod

ucti

on

, '0

00

tMain grain cropsSoybeanCorn

WheatSunflower

0

500

1,000

1,500

2,000

2,500

9192

9394

9596

9798

9900

0102

03

Fe

rtiliz

er

co

nsu

mp

tio

n, '0

00

t Other fertilizersP fertilizersN fertilizers

FFFFFigurigurigurigurigure 2.e 2.e 2.e 2.e 2. Evolution of consumption of N, P, andother fertilizers in Argentina, 1991-2003. Adapted from data of SAGPyAand Fundación Producir Conservando.

-2,400

-2,100

-1,800

-1,500

-1,200

-900

-600

-300

0

300

600

900

1,200

'00

0 t

WheatCornSunflowerSoybean

30%

15%2%40%

a

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Replenishment

N P K S

-2,400

-2,100

-1,800

-1,500

-1,200

-900

-600

-300

0

300

600

900

1,200

'00

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47%

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b

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N P K S

WheatCornSunflowerSoybean

FFFFFigurigurigurigurigure 3.e 3.e 3.e 3.e 3. Nutrient removal and replenishment in the four major grain crops of Argentina estimated for the 2003/04 season (a) and projected for the 2010/11 season (b). The estimate for N removed by soybeans wasreduced by 50% considering N supplied by biological N fixation. Adapted from data of SAGPyA andFundación Producir Conservando.

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Better Crops/Vol. 89 (2005, No. 1) 35

the potential increase for K fertilizerconsumption is also included, fertil-izer consumption by 2011 wouldequal 5.3 M t. Based on the proposednutrient replenishment rates, amarked improvement in the removalto application ratios is expected ,with values equal to: 2.1, 1.2, 22.8,and 4.2 for N, P, K, and S, respec-tively (FigurFigurFigurFigurFigure 3be 3be 3be 3be 3b).

Most of the increase would be attributedto P fertilizers. Since soybeans will continueas the main crop, future increases in N appli-cation would be much less pronounced com-pared to P. The expansion of soybean monoc-ulture raises concern not only because of thedeficit in soil N replacement, but also becauseof low carbon (C) inputs (i.e. organic matter)to the soil. Grasses as cover crops and a higherproportion of corn and wheat in the rotationwould increase N fertilizer demand, but couldalso help to improve soil C and N balances.Crop-pasture rotations, historically the mainrotation in the Pampas, are another possibil-ity to improve soil organic matter balancesand soil C and N.

Field rField rField rField rField researesearesearesearesearch has prch has prch has prch has prch has provided strovided strovided strovided strovided strong supporong supporong supporong supporong support for the adoption oft for the adoption oft for the adoption oft for the adoption oft for the adoption ofbalanced ferbalanced ferbalanced ferbalanced ferbalanced fertilization prtilization prtilization prtilization prtilization programs, not only because of the agrograms, not only because of the agrograms, not only because of the agrograms, not only because of the agrograms, not only because of the agronomiconomiconomiconomiconomicand economic rand economic rand economic rand economic rand economic results, but also because of the possibility of presults, but also because of the possibility of presults, but also because of the possibility of presults, but also because of the possibility of presults, but also because of the possibility of provid-ovid-ovid-ovid-ovid-ing a better soil nutrient balance.ing a better soil nutrient balance.ing a better soil nutrient balance.ing a better soil nutrient balance.ing a better soil nutrient balance. Besides general responses to N, P,and S, responses to other nutrients such as boron (B), chloride (Cl), andzinc (Zn) have been reported. BC

Dr. García is Director, PPI/PPIC Latin America–Southern Cone Program (INPOFOSCono Sur; e-mail: [email protected]. Mr. Oliverio, Mr. Segovia, and Mr. López arewith Fundación Producir Conservando; e-mail: [email protected].

ReferencesReferencesReferencesReferencesReferencesAndriulo, A., J. Galantini, and F. Abrego. 1996. Información Técnica Nº 147, XIV, 1-10. EEA

INTA Pergamino. Buenos Aires, Argentina.García, F. 2001. Informaciones Agronómicas del Cono Sur. No. 9 p. 1-3. INPOFOS Cono Sur,

Acassuso, Buenos Aires, Argentina.Oliverio, G. and G. López. 2002. Fundación Producir Conservando. Buenos Aires, Argentina.

Available at http://www.producirconservando.org.ar/, verified 4/11/04.Oliverio, G., F. Segovia, and G. López. 2004. Fundación Producir Conservando. Buenos Aires,

Argentina. Available at http://www.producirconservando.org.ar/, verified 4/11/04.

TTTTTable 1.able 1.able 1.able 1.able 1. Percentage of replenishment of N, P, and S used toestimate potential nutrient needs in some counties ofArgentina (Oliverio et al., 2004).

Replenishment, %County/Department Province N P S

Bahía Blanca Buenos Aires 75 100 60Cap. Sarmiento Buenos Aires 88 100 60Gral. Alvarado Buenos Aires 63 100 40Gualeguay Entre Ríos 88 100 40Marcos Juarez Córdoba 88 100 6025 de Mayo Buenos Aires 75 100 60Venado Tuerto Santa Fe 88 100 60

TTTTTable 2.able 2.able 2.able 2.able 2. Percentage of replenishment of N, P, and S incorn, soybean, sunflower, and wheatestimated for 2002/03 and projected for2010/11 (Oliverio et al., 2004).

Replenishment, %Crop Year N P S

Corn 2002/03 55 103 32010/11 74 138 25

Soybean 2002/03 0 19 52010/11 0 54 24

Sunflower 2002/03 4 37 32010/11 99 100 25

Wheat 2002/03 77 190 02010/11 77 190 25

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36 Better Crops/Vol. 89 (2005, No. 1)

1/04

New Leaf Color Chart for EffectiveNitrogen Management in RiceBy C. Witt, J.M.C.A. Pasuquin, R. Mutters, and R.J. Buresh

Leaf color charts (LCC) offer substantial opportunities for farmers toestimate plant nitrogen (N) demand in real time for efficient fertilizeruse and high rice yields. We developed a new, standardized LCC forrice in Asia based on the actual colors of rice leaves. The new chartand updated guidelines for its use are promoted in many Asian coun-tries through the Irrigated Rice Research Consortium (IRRC).

Asian farmers generally apply fertilizer N in several splitapplications, but the number of splits, amount of N applied persplit, and the time of applications vary substantially. The appar-

ent flexibility of rice farmers in adjusting the time and amount of fertil-izer application offers potential to synchronize N application with thereal-time demand of the rice crop.

Improved N management and balanced fertilization are key compo-nents of the site-specific nutrient management (SSNM) approach devel-oped by the International Rice Research Institute (IRRI) in partner-ship with the National Agricultural Research and Extension Systems inAsia. Field studies in major irrigated rice areas have shown significantyield and profit increases with SSNM over typical farmer fertilizer prac-tice (Dobermann et al., 2004). These studies revealed that sub-optimal Nmanagement by farmers is a key constraint to increasing yield (FigurFigurFigurFigurFigureeeee11111). Improved N management caused greater yield responses to fertilizerN application compared to farmer practice, and yield responses to fertil-izer phosphorus (P) and potassium (K) application often only occurredafter yields increased through improved N management with SSNM. Leafcolor charts are an effective, low-cost tool that can assist farmers in im-

proving their N management, and efforts are un-derway to promote the technology at wider scaleamong Asian rice farmers.

Numerous LCC units have been fabricated anddistributed to farmers in a number of Asiancountries since the 1990s. The most widely usedLCC was developed by IRRI in collaboration with

S O U T H E A S TA S I A

FFFFFigurigurigurigurigure 1.e 1.e 1.e 1.e 1.Yield response to fertilizer N, P, and K applicationfollowing farmer fertilizer practice (FFP) and theSSNM approach on 179 farms at seven key siteswith irrigated rice in Asia, 1997-1999. AD =Aduthurai (Tamil Nadu, India), OM = Omon(Cantho, Vietnam), HA = Hanoi (Vietnam), JI =Jinhua (Zhejiang, China), MA = Maligaya (NuevaEcija, Philippines), SU = Sukamandi (West Java,Indonesia), TH = Thanjavur (Tamil Nadu, India).

AD OM HA JI MA SU TH0

500

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1,500

2,000

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in y

ield

re

spo

nse

, kg

/ha

AD OM HA JI MA SU TH-500

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500

1,000

1,500

SiteAD OM HA JI MA SU TH

-500

0

500

1,000

1,500

FFPSSNM

Nitrogen

Phosphorus

Potassium

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Better Crops/Vol. 89 (2005, No. 1) 37

the Philippine Rice Research Institute(Balasubramanian et al., 1998). Fueled by thesuccess of the chart and an increasing demandfor quality and low-cost LCCs in Asia, we usedan approach developed at the University of California Cooperative Ex-tension (UCCE) to improve and standardize the colors of the LCC. Inthis approach, a meaningful range of green plastic chips ranging fromyellowish green to dark green match the color range of rice leaves thatcover a continuum from leaf N deficiency to excessive leaf N content.This approach was first used to develop an LCC for California rice variet-ies (FigurFigurFigurFigurFigure 2e 2e 2e 2e 2). A systematic analysis using a Minolta CM 3700-d spectro-photometer showed that the colors of LCCs available in Asia do not matchthose of rice leaves (Witt and Pasuquin, unpublished).

We used actual leaf spectral reflectance measurements from a 2-sea-son field experiment in 2001 involving 10 modern rice varieties grown atthree different N levels to develop target reflectance patterns for an idealLCC prototype (Witt et al., 2004). A spectral reflectance pattern describesthe composition of light that is reflected from a rice leaf across the wholespectrum of wavelength from blue (400 nm), over green (550 nm) to in-frared (700 nm). Based on the target pattern (FigurFigurFigurFigurFigure 3Ae 3Ae 3Ae 3Ae 3A), we workedwith the local pigmentand plastic industries inthe Philippines and pro-duced a standardizedchart that captures therelevant range of riceleaf colors in Asia. Thenew 4-panel LCC isshown in FigurFigurFigurFigurFigure 4e 4e 4e 4e 4. Wechose only 4 color pan-els for the LCC becauseany color outside thisrange would not be adesirable goal for mod-ern, high yielding vari-eties in Asia as it wouldeither be a sign of ex-treme N deficiency orexcess supply of N.

The quality of thenew 4-panel LCCwas evaluated usingspectral reflectance (SR)m e a s u r e m e n t s(Figure 3Figure 3Figure 3Figure 3Figure 3). In thisanalysis, we comparedSR patterns of rice andmaize leaves with those

FFFFFigurigurigurigurigure 2.e 2.e 2.e 2.e 2. The leaf color chart developed by Universityof California Cooperative Extension (UCCE)for rice in California.

D) IRRI-UCCE LCC4 Panels

C) UCCE LCC8 Panels

400 450 500 550 600 650 70005

10152025303540

B)Target patternMaize leaves

Wavelength, nm

400 450 500 550 600 650 700

Re

fle

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nce

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400 450 500 550 600 650 70005

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A) Target patternRice leaves

400 450 500 550 600 650 70005

10152025303540

FFFFFigurigurigurigurigure 3.e 3.e 3.e 3.e 3. Target spectral reflectance patterns for a theoretical LCC based onactual reflectance measurements performed on leaves of major Asianrice varieties (A) and of a maize variety (B). Actual reflectance patternsfor LCCs developed by UCCE for Californian rice varieties (C) and IRRI-UCCE for Asian rice varieties (D). The dotted line at 550 nm (green)reflects the maximum reflectance of actual rice and maize leaves inthe visible spectrum. The top line in each chart represents the lightestgreen, while the lowest line represents the darkest green.

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38 Better Crops/Vol. 89 (2005, No. 1)

of the two leafcolor charts devel-oped by UCCE andIRRI. Recognizingtechnical limita-tions in plasticmanufacturing, thetwo LCCs achieveda respectable match

with actual SR patterns of rice and maize leaves (FigurFigurFigurFigurFigure 3CD vs 3ABe 3CD vs 3ABe 3CD vs 3ABe 3CD vs 3ABe 3CD vs 3AB).Typical SR patterns of rice and maize leaves were similar (FigurFigurFigurFigurFigure 3ABe 3ABe 3ABe 3ABe 3AB)with greatest reflectance and sensitivity at 550 nm (green). Leaves withdifferent N content would, therefore, differ greatly at this bandwidth,while differences in reflectance decrease towards both ends of the spec-trum. Color panels of both charts had their greatest reflectance at 550nm so that this condition was met. Further, the plastic panels showedequidistant reflectance among color panels at 550 nm (FigurFigurFigurFigurFigure 3CDe 3CDe 3CDe 3CDe 3CD), whichmeans that the change in color was consistent from panel to panel. Thisconfirmed the visual impression that colors of neighboring panels can beeasily distinguished in both charts (FigurFigurFigurFigurFigure 2 and 4e 2 and 4e 2 and 4e 2 and 4e 2 and 4). The comparisonshown in FigurFigurFigurFigurFigure 3e 3e 3e 3e 3 also indicated that the new 4-panel chart may be moresuitable for rice varieties in Asia compared to the LCC that was devel-oped for rice varieties in California.

The new 4-panel LCC can be used for all modern, high yielding ricevarieties in Asia, but guidelines on the use of the chart have to be ad-justed to local conditions. Major progress has been made in recent yearsin the on-farm evaluation of LCC for effective N management and thegeneral guidelines on its use are provided in greater detail elsewhere(Fairhurst and Witt, 2002). Briefly, a critical leaf color has to be main-tained for optimal growth and the LCC provides guidance when to applyfertilizer N to avoid N deficiency. The critical leaf color depends on vari-etal group (inbred, hybrid, new plant type) and crop establishmentmethod (planting density). There are two major approaches in the use ofthe LCC. The fixed splitting pattern approach provides a recommendationfor the total N fertilizer requirement (kg/ha) and a plan for splitting andtiming of applications in accordance with crop growth stage, croppingseason, variety used, and crop establishment method. The LCC is used atcritical growth stages to decide whether the recommended standard Nrate would need to be adjusted up or down based on leaf color. In thereal-time approach, a prescribed amount of fertilizer N is applied when-ever the color of rice leaves falls below the critical LCC value. Thecritical value might fall between two existing panels of the LCC, butguidelines can be adjusted so that the color panels of the LCC will nothave to be changed. Local guidelines on the LCC use have now beendeveloped for the major irrigated rice domains in Asia.

Since its introduction in December 2003, more than 250,000 units ofthe 4-panel LCC have been produced and will be distributed to Asian ricefarmers in Bangladesh, China, India, Indonesia, Myanmar, the

FFFFFigurigurigurigurigure 4.e 4.e 4.e 4.e 4. The new 4-panel LCC developed by IRRI in collaboration with UCCE for rice(left). The same chart might also be a useful tool in maize (right).

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Better Crops/Vol. 89 (2005, No. 1) 39

Philippines, Thailand, and Vietnam. Research is underway to evaluatethe suitability of the LCC for N management in maize in a joint collabo-rative project between the Indonesian Agency for Agricultural Researchand Development and the PPI/PPIC-IPI Southeast Asia Program. BC

Note: For availability and guidelines on the use of the LCC in rice, please contact Dr. R.G. Mutters(UCCE chart) or Dr. R.J. Buresh (IRRI-UCCE chart).

Dr. Witt is Director, PPI/PPIC-IPI Southeast Asia Program, Singapore; e-mail:[email protected]. Ms. Pasuquin is Agronomist, PPI/PPIC-IPI Southeast AsiaProgram; e-mail: [email protected]. Dr. Mutters is Cooperative ExtensionAdvisor, University of California Cooperative Extension, Oroville, California;e-mail: [email protected]. Dr. Buresh is Soil Scientist at IRRI, Los Baños,Philippines; e-mail: [email protected].

AcknowledgmentsAcknowledgmentsAcknowledgmentsAcknowledgmentsAcknowledgmentsThe International Rice Research Institute (IRRI), the Swiss Agency for De-

velopment and Cooperation (SDC), PPI/PPIC, and the International Potash In-stitute (IPI) provided funding for this research.

ReferReferReferReferReferencesencesencesencesencesBalasubramanian V., J.K. Ladha, G.L. Denning. (eds.). 1998. Resource management in rice

systems: Nutrients. The Netherlands: Kluwer Academic Publishers. 600 p.Dobermann, A., C. Witt, and D. Dawe. (eds.). 2004. Increasing productivity of intensive rice

systems through site-specific nutrient management. Enfield, NH (USA) and Los Baños(Philippines): Science Publishers, Inc., and International Rice Research Institute(IRRI). 410 p.

Singh B., Y. Singh, J.K. Ladha, K.F. Bronson, V. Balasubramanian, J. Singh, and C.S.Khind. 2002. Agron. J. 94: 821-829.

Fairhurst, T. and C. Witt (eds.). 2002. Rice: a practical guide for nutrient management.Singapore: Potash & Phosphate Institute/Potash & Phosphate Institute of Canada; andLos Baños: International Rice Research Institute. 89 p.

Witt, C., J.M.C.A. Pasuquin, and R. Mutters. 2004. Proceedings of the 4th InternationalCrop Science Congress, Brisbane, Australia, 26 Sep � 1 Oct 2004.www.cropscience.org.au/icsc2004.

ThisThisThisThisThis isisisisis the actual size ofthe new 4-panel LCC.

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Potash & Phosphate InstituteSuite 110, 655 Engineering Drive

Norcross, Georgia 30092-2837

PeriodicalsPostage

PPPPPOOOOOTTTTTASHASHASHASHASH & P & P & P & P & PHOSPHAHOSPHAHOSPHAHOSPHAHOSPHATETETETETE I I I I INSNSNSNSNSTITUTETITUTETITUTETITUTETITUTE: S: S: S: S: STILLTILLTILLTILLTILL G G G G GOINOINOINOINOINGGGGG S S S S STRTRTRTRTRONONONONONGGGGG A A A A ATTTTT 70 70 70 70 70When PPI observed its 50-year milestone back in 1985, several events

focused on the remarkable achievements of this science-based nutrient managementorganization. A symposium in Atlanta drew leading scientists, industry personnel, andothers from around the world. Speakers presented papers dealing with all aspects of K,from mining and distribution to the technical physiological aspects of K utilization inplants�and everything in between. The highly acclaimed book Potassium for Agricul-ture was published by the American Society of Agronomy and introduced at that event.Also, a special issue of Better Crops with Plant Food highlighted the history of the Insti-tute, beginning with its founding in Washington, DC, back in 1935.

In April of this year, the Institute will be 70 years old. There are no special cel-ebrations planned. That�s to be expected, since 70 is one of those in-between years, notas impressive as 50 or 65 or 75. Yet, this is a special year at PPI because it marks thecontinuing support of the Institute�s member companies, producers of P and K. Hav-ing been a part of the Institute family for more than 30 years, I have long since recog-nized the uniqueness of the industry support which the Institute has enjoyed (andearned) during the past 70 years.

The financial commitment of PPI members to the Institute, with its Ph.D. levelscientists and support staff strategically located around the world, is significant. Itis critical that such support be steady and long-term. Otherwise, the internationallyrespected professionals working at PPI could not be attracted to and would not remainwith the organization, research and education programs could not be sustained, andthe scientific approach to market development could not endure.

The fact that industry supports the scientific approach to advancing appropriateP and K use is a reflection of the vision of industry leaders, a vision that has spannedseven decades and continues today. Through good times and bad, PPI�s members havestood their ground and held tightly to the ideals of sound science and integrity in devel-oping the global markets for their products. So, I wish a happy 70th birthday to PPIand offer a special thanks to the Institute�s members for 70 years of progress andsteadfast support of the vision that created and continues to carry this wonderfulorganization�the Potash & Phosphate Institute.

61885_40.p65 2/3/2005, 10:44 AM32