Current N Fertilization Strategy for Corn
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Current N Fertilization Strategy for Corn in Missouri Newell Kitchen Cropping Systems and Water Quality Research Unit Columbia, Missouri USDA-ARS. Major Soil Regions in Missouri. Table 2. Nitrogen rate adjustments 1. Table 2. Nitrogen rate adjustments 1.

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Current N Fertilization Strategy for Corn in MissouriNewell KitchenCropping Systems and Water Quality Research UnitColumbia, MissouriUSDA-ARS



Table 2. Nitrogen rate adjustments1.

Table 2. Nitrogen rate adjustments1.

Missouri Corn Nitrogen Requirement (NR):

University of Missouri:

NR (lbs/A) = POP x 4 + 0.9 x YG – MN

Where:

POP is the plant population in 1000s

YG is expected yield in bu/A

MN is the expected N mineralization from SOM

An example calculation for nitrogen requirement on corn:

An example calculation for nitrogen requirement on corn:


Table 2. Nitrogen rate adjustments1.

Table 2. Nitrogen rate adjustments1.

Soil texture

Cation exchange capacity (me/100 g.)

Organic matter (%)

Cool-season crops (lbs. N/A)

Warm-season crops (lbs. N/A)

Sands — sandy loam

less than 10

0.51.01.5

102030

204060

Silt loams — loam

10 to 18

2.03.04.0

203040

406080

Clay loams — clays

greater than 18

2.03.04.05.0

10152025

20304050

1Based on soil texture, organic matter and time of major growth.

Nitrogen rate adjustment based upon

soil texture, organic matter, and time of major crop

An example calculation for nitrogen requirement on corn:

An example calculation for nitrogen requirement on corn:


Table 2. Nitrogen rate adjustments1.

Table 2. Nitrogen rate adjustments1.

Missouri Corn Nitrogen Requirement (NR):

MFA:

NR (lbs/A) = 1.5 x YG - MN - PCA

Where:

YG is expected yield in bu/A

MN is the expected N mineralization from SOM

PCA is the previous crop addition (ex. 20 for soybean)

A CEC adjustment within MN is an attempt to correct for N loss associated with leaching in low CEC soils and denitrification in high CEC soils. A CEC of 10 (silt loam) was set as the pivot point.

An example calculation for nitrogen requirement on corn:

An example calculation for nitrogen requirement on corn:


MFA’s Previous Crop N Credit for common crops in the Lower Midwest

Previous CropNitrogen Credit (lbs./acre)

Soybeans 10

Winter Wheat -10

Corn -10

Milo -20

Cotton -10

Rice -20

Alfalfa (1/2 stand) 40


Given: A soil test CEC = 10, O.M. = 2.0, previous crop = corn, plant population = 28,000.

What are the MFA and University of Missouri N Recommendations for a yield goal of 160 bu/A corn?

Exactly the same: 200 lbs N/A


Other Important N BMPs in Missouri corn, plant population = 28,000.

  • For river bottom soils and irrigated fields, farmers are encouraged to side-dress the majority of N

    • about 90% of “boot-heel” farmers side-dress


Other Important N BMPs in Missouri corn, plant population = 28,000.

  • The preplant N test is advocated under certain conditions:

  • on fields that have received manure anytime since the previous summer.

  • on fields that have a history of heavy manure applications.

  • following a drought year on fields with a high potential for carry over for fertilizer N.

  • following fall and early spring fertilizer applications where excessive rainfall may have caused losses of fertilizer N.


Nitrogen source corn, plant population = 28,000.

Corn yield1

Ammonium nitrate (34-0-0)

149

Urea (46-0-0)

142

UAN solution (32-0-0)

132

1Average across 8 site years in Missouri

Other Important N BMPs in Missouri

  • Ammonium nitrate is the preferred source of nitrogen in no-till when injection is not possible and the material must be surface broadcast.


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