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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
Topics
• Nutrient loss from crop mining
• Evaluation of soil nutrient supply and best soil level
• Fertilizer recommendations based on soil tests and yield goal
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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.
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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.
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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.
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
Liming Reaction
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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.
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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.
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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.
Genuity® Corn-on-Corn Clinic
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
Genuity® Corn-on-Corn Clinic
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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