Ray Ward Ward Laboratories, Inc Kearney Nebraska …. Ray Ward.pdfRay Ward Ward Laboratories, Inc...

Fertility Management “Corn on Corn”

Ray Ward

Ward Laboratories, Inc

Kearney Nebraska

www.wardlab.com

“Guiding Producers Today to Feed the World Tomorrow”

Genuity® Corn-on-Corn Clinic

http://www.wardlab.com/

Topics

• Nutrient loss from crop mining

• Evaluation of soil nutrient supply and best soil level

• Fertilizer recommendations based on soil tests and yield goal


Nutrient Crop Mining

CORN

Nutrient lb/bu 200 bu/A

Nitrogen, N 0.75 150

Phosphorus, P2O5 0.33 66

Potassium, K2O 0.23 46

Sulfur, S 0.09 18

Zinc, Zn 0.001 0.2

Nutrient Crop Mining CORN

Nutrient lb/bu 200 bu/A

Chloride 0.024 4.8

Manganese 0.0006 0.12

Iron 0.0012 0.24

Copper 0.0004 0.08

Boron 0.0006 0.12

Molybdenum 0.00001 0.002

Mobile Nutrients

• Nitrate

– Nitrate is soluble.

– We only want to apply the amount of N that is needed for the current crop.

– The goal is to have 2 to 5 ppm NO3-N after harvest. More than 5 ppm NO3-N indicates more N was applied than the crop could use. If residual nitrate is left the N application for the next crop should be reduced.

Phosphorus (My Goals)

• Ideal Phosphorus Soil Test (Mehlich P-3 or Bray P-1):

– Dryland areas = 22-28 ppm P

– Irrigated/high rainfall areas = 30-40 ppm P

• How to Get There

– Soil texture: loam or heavier

• 18 lbs of P2O5 to raise soil P test 1 ppm P

– Soil texture: sand to sandy loam

• 12 lbs of P2O5 to raise soil P test 1 ppm P


Phosphorus

• Example for a silt loam

– My soil test is 15 ppm P and I want to get to 35 ppm P

• 35 – 15 = 20 ppm P increase

• 20 X 18 = 360 lbs of P2O5 to raise soil P test to 35

• 360 /0.52 = 692 lbs of 11-52-0

• How many years do you want to take to get there? Divide by the number of years . This application is in addition to amount you normally apply.


Potassium (My Goal)

• Ideal Potassium Soil Test:

– Dryland K soil test = 160-200 ppm K

– Irrigated/high rainfall =200-250 ppm K

• How to Get There

– Soil texture loam or heavier

• 9 lbs of K2O to raise soil K test 1 ppm K

– Soil texture sandy loam to sand

• 5 lbs of K2O to raise soil K test 1 ppm K


Potassium

• How to Get There Example for a silt loam

– Soil test is 150 ppm K and I want to get to 200 ppm K

• 200-150 = 50 ppm increase

• 50 X 9 = 450 lbs of K2O

• 450 /0.60 = 750 lbs of 0-0-60

• How many years do you want to take to get there? Divide by the number of years . This application is in addition to amount you normally apply.


Zinc

• I have found that the best way to correct a low zinc soil test is to broadcast enough zinc sulfate (33 to 36 % Zn) to raise the zinc soil test above 1 ppm. Then apply zinc each year with the starter fertilizer or once every 6 years or so.

• One pound of actual zinc will raise the zinc soil test 0.1 ppm Zn. – Zn recommendation = (1.0 – Zn soil test) times 10

– Zn soil test = 0.60: (1.00 – 0.60 ppm Zn) X 10 = 4 lbs of Zn/A


Manganese and Iron

• Manganese and iron react very quickly with oxygen in the soil air forming oxides that decrease their availability.

• Therefore, if soil tests are low you will have to apply annually.

• Manganese sulfate and ferrous (reduced iron) sulfate can be soil applied or chelates can be applied as foliar treatments.


Copper

• Copper soil tests are low in a few areas of the Plains.

• For most crops I like to see a copper (Cu) value of 0.20 ppm Cu. For a few crops like potatoes we raise the Cu soil test to 0.60 ppm Cu.

• Three pounds of Cu will raise the soil test 0.10 ppm Cu

• Cu rec. = (0.20 - .12 ppm Cu) X 3 = 2.4 lbs of Cu


Boron

• Boron has a narrow safe range. Do not try to build B soil test. Boron should be applied for corn when the B hot water soluble test is less than 0.25 ppm B.

• B recommendation = One pound of B will raise the B soil test 0.10 ppm B. Example: for wheat, corn, milo, etc.

• 1.5 – (5 x 0.20 ppm B) = (1.5 – 1.0) = 0.5 lbs B


Liming Reaction


Calcium and Magnesium

• Lime

– 480 lbs of Ca per ton of 60 % ECC

• Corn Stover

– 9.7 lbs of Ca per ton of dry forage

– 3.4 lbs of Mg per ton of dry forage

• Soybean Stubble

– 27.0 lbs of Ca per ton of dry forage

– 7.8 lbs of Mg per ton of dry forage


Calcium:Magnesium Ratio

In summary, the Ca:Mg ratio concept is

unproven and should not be used as a

basis for fertilization or liming practices.

Having sufficient levels of Ca and Mg is

the proper method of evaluation, rather

than trying to manipulate ratios.


University of Minnesota, Corn

Application

Low-P Soil

Three-year Average Corn Yield

Method Lbs P2O5/acre Bushels per Acre

None 0 148.0

Pop-up 25 158.1

Deep Band 25 157.7

Broadcast 25 166.4

Deep and Pop-up 50 171.5

Pop-up 50 165.7

Deep Band 50 166.0

Broadcast 50 167.0

Crops and Soils, ASA Genuity® Corn-on-Corn Clinic

University of Minnesota, Corn

Application

High-P Soil Three Year Average Corn Yield

Method Lb P2O5/acre Bushels per Acre

None 0 192.8

Pop-up 20 191.6

Deep Band 20 196.4

Broadcast 20 196.2

Deep and Pop-up 40 189.0

Pop-up 40 194.5

Deep Band 40 186.4

Broadcast 40 190.2

Crops and Soils, ASA Genuity® Corn-on-Corn Clinic

Importance of Phosphorus Tribune (KSU)2004

N+P2O5, lbs/A Corn Yield, Bu/A

0+0 67

40+0 92

80+0 118

120+0 103

160+0 136

200+0 162


Importance of Phosphorus Tribune (KSU)2004

N+P2O5, lbs/A Corn Yield, Bu/A

0+40 97

40+40 148

80+40 209

120+40 228

160+40 231

200+40 234


Conclusions

• Highest crop yield are associated with high soil tests for phosphate, potash, and zinc and properly managed rates of nitrogen and sulfur.

• Question: Can we continue to reach the higher yields if we use a fertility approach that minimizes fertilizer application, especially phosphorus and potassium?

Two Approaches for Interpreting Soil Test Values

• Nutrient Sufficiency

– Apply just enough to maximize profitability in the year of fertilizer application

• Build – Maintenance

– Manage soil tests to desired soil test levels and then apply enough fertilizer to maintain the desired soil values


Nitrogen Requirement

Corn 1.2 lbs N/Bu

This is the amount of N in the plant and in

the grain. The plant needs this much to

grow the desired yield. It is not the

amount of N fertilizer to apply.


Nitrogen Recommendation for Corn

Recommendation, lbs N/A = (yield * N req.)

Minus lbs of NO3-N in 24 or 36”

Minus Legume credit

Minus Manure credit

And minus Irrigation water credit


Suggested N Credits for Legume Crops

% Stand lb. N/A

Alfalfa 100% 100

50% 50

less than 50% none

Sweet Clover (green manure) 80

Red Clover 50

Soybeans 20-50

Dry Beans 20-30


Sulfur Requirement for Corn

Crop Yield Unit Lbs of S/Bu

Corn Bushel 0.22

This is the amount of Sulfur needed to grow

the crop NOT the amount of sulfur fertilizer

to apply.


Sulfur Recommendation Example

Corn 200 bu/A Yield Goal

Sulfur Requirement is 0.22 lb S/bu

Total S Required is 44 lbs/A

Sulfate Soil Test is 8 ppm S

Lbs of S in the soil is 8 X 2.4 = 19 lbs S/A

Recommendation is 24 lbs S/A


Sulfur

• Sulfate is soluble and moves with soil water like nitrate. Do not try to build sulfate. Some soils have sulfate in the subsoil which reduces the need for sulfur.

• Some irrigation water is high in sulfate.

• Apply sulfur fertilizer when soil test for sulfate is low.

Sulfur Soil Test, Ca-P Extractable

Soil Test ppm S Rating

0-4 Very Low

5-8 Low

9-12 Medium

13-17 High

18 + Very High

Chloride

• Chloride is a soluble ion like nitrate, but does not move as fast as nitrate.

• Many soils are low in chloride where potash fertilizer is not used.

• 0-0-60 is potassium chloride, so it is 60 % K2O and 45 % Chloride

• Some irrigation water contains enough chloride for crop needs.

Soil test chloride interpretations and fertilizer recommendations for Kansas.

____________________________________________________________

Soil Chloride in a 0-24" sample Cl Recommended* Category lb/acre ppm lb/acre

__________________________________________________________ Low <30 <4 20 Medium 30-45 4-6 10

High > 45 >6 0 __________________________________________________________

*Recommendations for corn, sorghum and wheat only.

Phosphorus Recommendations for Corn

Soil Test ppm K Rating lbs K2O 0-40 Very Low 90-200 41-80 Low 50-120 81-120 Medium 25-60 121-200 High 0-35 201+ Very High None

Potassium Recommendations for Corn

Sulfur Recommendation Example

Wheat 80 bu/A Yield Goal Sulfur Requirement is .28 to .35 lb S/bu

Total S Required is 22 to 28 lbs/A

Sulfate Soil Test is 8 ppm S

8 ppm X .3 X 8 inches = 19 lbs S/A

Recommendation is 3 to 9 lbs S/A

Sulfur Recommendations lbs S per acre

Soil Sulfur Test

5 ppm S 7 ppm S

Corn, 200 bu/A 28 23

Milo, 150 bu/A 21 16

Canola, 50 bu/A 27 22

Wheat, 100 bu/A 21 16

Alfalfa, 8 ton/A 25 20

Zinc Soil (DTPA) Test and

Recommendations

Corrective Rate

Soil Test ppm Zn lb Zn/A

0-0.25 3-12

0.26-0.50 1-7

0.51-.75 0-6

0.76-1.00 0-3

1.01+ None

*Annual rate: Divide Corrective Rate by 6.

Manganese Soil Test (DTPA) and

Recommendations

Mn Rate

Mn Soil Test, ppm Rating Lbs Mn/A

0-0.5 Very Low 12

0.6-1.5 Low 7-12

1.6 – 3.0 Medium 2-6

3.1 - 4.0 High 0-1

4.0 + Very High 0

Copper Soil Test (DTPA) and

Recommendations

Cu Rate**

Cu Soil Test, ppm Rating Lbs/A

0-0.10 Very Low 3-6

0.11-0.20 Low 1-2

0.21-0.30 Medium 0

0.31-0.60 High* 0

0.61+ Very High 0 • * Specialty crops get Copper up to 0.60 ppm

• ** Corrective application rate

Boron Soil Test and Recommendations

Boron Rate

Boron Soil Test, ppm Rating Lbs B/A

0 – 0.25 Low 0.5 – 3.0

0.26 – 0.50 Medium 0.0 – 1.7

0.51 + High 0

Alfalfa, clover, peanuts, cotton and sugar beets require more

boron than other crops.

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