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Research Challenges from Research Challenges from and and forfor High Yield Growers High Yield Growers
International Conference on Precision Agriculture
Minneapolis, MNJuly 26, 2004
Paul FixenPotash & Phosphate Institute
Scientists andScientists andfarmersfarmers
Is this session appropriate for a precision Is this session appropriate for a precision agriculture conference?agriculture conference?
Precision in management gets more Precision in management gets more critical as yield potential climbs …critical as yield potential climbs …
- agronomic reasons- agronomic reasons- environmental reasons- environmental reasons
Summary:Summary:Research challenges from high yield growers Research challenges from high yield growers
A large gap exists between maximum attainable and typical yields
Observing the practices of high yield growers through the lens of scientific principles and controlled research can be revealing and lead to researchable questions for scientistsscientists and farmersfarmers
Modern technologies should facilitate narrowing the gap between attainable and typical yields
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1965 1970 1975 1980 1985 1990 1995 2000
Year
Corn
yie
ld, bu/A
Exploitable yield potential in cornExploitable yield potential in corn
IA State Average1.7 bu/A/yr
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1965-19912.0 bu/A/yr
H. WarsawSaybrook, IL
F. ChildsManchester, IA
20 bu/A/yr
* *
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Iowa exampleIowa example
IA Contest Winners
Top corn yields from researchers in Top corn yields from researchers in 1982 1982
Dr. Roy FlanneryDr. Roy FlanneryNew JerseyNew Jersey
338 bu/A338 bu/A
Dr. Sterling OlsenDr. Sterling OlsenColoradoColorado
332 bu/A332 bu/A
From Saybrook, IL to Manchester, IAFrom Saybrook, IL to Manchester, IA
Manchester, IA
Saybrook, IL
Growing season precip: very similar at 27-28”Growing degree Days: Manchester - 2980
Urbana – 3513
Property Childs Warsaw Soil type Kenyon loam Parr silt loamTaxonomy Typic Hapludolls Oxyaquic ArgiudollsOrg. mat., % 5.5-6.0 4.5-5.8pH 5.3-6.1 6.0P1, ppm 126 (VH) 81 (VH)K, ppm 374 (VH) 400 (VH)
Source: Childs – Murrell and Childs, 2000; Smith,2000; Dobermann, 2002; Warsaw – PPI, 1986.
From Saybrook, IL to Manchester, IA: From Saybrook, IL to Manchester, IA: Soil OMSoil OM
Manchester, IA
Saybrook, IL
Depth, In Childs Warsaw-light Warsaw-dark Organic matter, % 0-6 5.6 5.8 4.5 6-12 4.5 4.9 3.9 12-18 3.0 3.2 4.3 18-24 --- 1.4 4.3 24-30 --- 0.8 3.8 30-36 --- 0.6 3.6
Source: Childs data – Dobermann, 2002. Warsaw data – PPI, 1977.
Warsaw: 20 years of intensively managed continuous corn Childs: 35 years of intensively managed continuous corn
From Saybrook, IL to Manchester, IA: From Saybrook, IL to Manchester, IA: PracticesPractices
Manchester, IA
Saybrook, IL
Practice Childs Warsaw Fall tillage Mini MP 14” deep CH 14” deepHybrid 2001-34M95; 2002-34N44 FS 854Harv. Population 34,000 - 40,000 36,000Row spacing 2001-30”; 2002-20” 28”Manure High rates in past 20 T/A annually
Fall P2O5+K2O none 250+250Fall N, lb/A 50(UAN) 45(DAP)Preplant N 250(NH3 + sep. stab.) 300(UAN)+ 100(AS)Starter, N+P2O5+K2O 6+15+15+ACA 26+26+26Popup, N+P2O5+K2O 4+9+4 nonePostplant N 50(UAN) 75(UR)2.5-4’ tall N 50(UAN+Guardian) None Fert N, lb/A 410(1.0 bu/lb) 546(0.7 bu/lb) Other nutrients Boron Sulfur
Research challenges: Which practices are Research challenges: Which practices are critical and at what level?critical and at what level?
Determination of site-specific attainable yield estimates (crop models)
Carbon cycling – crop and environmental impacts Crop rotation vs monoculture Tillage requirements … no till/strip till Minimum N requirements, NH4
+ vs NO3-, timing
Minimum soil test P and K requirements Role of subsoil fertility, organic matter, etc. (P. Nowak)(P. Nowak)
Role of manure application Role of secondary and micronutrients Importance of starter fertilizer (0.5% P at V3-V4 for
max kernel initiation/ear)
http://www.hybridmaize.unl.edu/http://www.hybridmaize.unl.edu/
Better Crops (2004, No. 1)
Real time yield prediction of current seasonReal time yield prediction of current season
U. of Nebraska EI Study - Lincoln
July 25, 2004
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349
279
Soil Test P and K requirements for Soil Test P and K requirements for very high yields: Classical theory very high yields: Classical theory
For soil immobile nutrients like P or K, the STL vs % yield relationship should not vary with site yield potential unless plant population increases enough for adjacent roots to compete with each other for P and K (Bray, 1954; Bray, 1963).
Roots normally occupy less than 1% of soil volume (Barber, 1984) … an increase in size of the root system translates into a greater volume of soil P or K being available for uptake.
As long as the size of the root system increases proportionally with yield, a higher yielding crop should not need a higher P or K concentration at the root surface … should not require a higher soil test level.
Soil Test P and K requirements for very Soil Test P and K requirements for very high yields: Conditions that could lead to high yields: Conditions that could lead to
higher requirementshigher requirements Shoot growth increases that exceed root growth
increases as yields climb Redistribution of roots from the surface soil to a low P or
K subsoil soil factors (organic matter, pH, structure, etc.) varietal factors – vertical vs lateral rooting tendencies
Each % increase in yield has greater economic value … want to be further up the response curve
Is “subsoil” fertility more important to today’s Is “subsoil” fertility more important to today’s high yield potential “stay-green” hybrids?high yield potential “stay-green” hybrids?
Probably taking up nutrients later in the season when surface soils are dryer
Higher % of active roots located deeper in profile
36 Days
8 Weeks Mature
Source: Weaver, 1926 Is manure important Is manure important because it moves P because it moves P
into subsoils?into subsoils?
Impact of Impact of hybridhybrid on the influence of on the influence of NN rate rate on yield response to plant on yield response to plant populationpopulation
S.R. Olsen, reported by W. M. Stewart, 2000
27K vs 38K 39K vs 46K
Colorado
Risk/benefit evaluation of yield Risk/benefit evaluation of yield improvement phasesimprovement phases
Phase Yield benefit and risk
Fully implement standard agronomic BMPs (site-specific) Minor
Experiment with optimizing setssets of easily controlled factors for higher yield levels
Ex: population, nutrients, hybrid
Moderate
Experiment with system-level changes, then re-optimize
Ex: tillage, row spacing, rotation
Major
Long-termLong-term soil quality improvement with continuous re-optimization
Ex: organic matter, subsoil properties, tilth
Long-term major
Summary:Summary:Research challenges from high yield growers Research challenges from high yield growers
A large gap exists between maximum attainable and typical yields
Observing the practices of high yield growers through the lens of scientific principles and controlled research can be revealing and lead to researchable questions for scientistsscientists and farmersfarmers.
Modern technologies should facilitate narrowing the gap between attainable and typical yields Simulation models to help define attainable yields and researchable
questions Improved weather data and management tools Site-specific technologies for greater efficiency Biotechnology for yield protection … and building
Research Challenges from Research Challenges from High Yield GrowersHigh Yield Growers
InfoAg 2003Indianapolis, IN
August 1, 2003
Paul Fixen
Potash & Phosphate Institute