Current N Fertilization Current N Fertilization Strategy for CornStrategy for Corn

in Missouri in Missouri

Newell KitchenNewell Kitchen Cropping Systems and Water Quality Research UnitCropping Systems and Water Quality Research Unit

Columbia, MissouriColumbia, MissouriUSDA-ARSUSDA-ARS

Current N Fertilization Current N Fertilization Strategy for CornStrategy for Corn

in Missouri in Missouri

Newell KitchenNewell Kitchen Cropping Systems and Water Quality Research UnitCropping Systems and Water Quality Research Unit

Columbia, MissouriColumbia, MissouriUSDA-ARSUSDA-ARS

Major Soil Regions in MissouriMajor Soil Regions in Missouri

Missouri Corn Nitrogen Requirement (NR):Missouri Corn Nitrogen Requirement (NR):Missouri Corn Nitrogen Requirement (NR):Missouri Corn Nitrogen Requirement (NR):

University of Missouri:University of Missouri:

NR (lbs/A) = POP x 4 + 0.9 x YG – MNNR (lbs/A) = POP x 4 + 0.9 x YG – MN

Where: Where: POP is the plant population in 1000sPOP is the plant population in 1000sYG is expected yield in bu/AYG is expected yield in bu/AMN is the expected N mineralization from SOMMN is the expected N mineralization from SOM

University of Missouri:University of Missouri:

NR (lbs/A) = POP x 4 + 0.9 x YG – MNNR (lbs/A) = POP x 4 + 0.9 x YG – MN

Where: Where: POP is the plant population in 1000sPOP is the plant population in 1000sYG is expected yield in bu/AYG is expected yield in bu/AMN is the expected N mineralization from SOMMN is the expected N mineralization from SOM

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

Nitrogen rate adjustment based upon soil texture, organic matter, and time of major crop

Missouri Corn Nitrogen Requirement (NR):Missouri Corn Nitrogen Requirement (NR):Missouri Corn Nitrogen Requirement (NR):Missouri Corn Nitrogen Requirement (NR):

MFA:MFA:

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

Where: Where: YG is expected yield in bu/AYG is expected yield in bu/AMN is the expected N mineralization from SOMMN is the expected N mineralization from SOMPCA is the previous crop addition (ex. 20 for soybean)PCA is the previous crop addition (ex. 20 for soybean)

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

MFA:MFA:

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

Where: Where: YG is expected yield in bu/AYG is expected yield in bu/AMN is the expected N mineralization from SOMMN is the expected N mineralization from SOMPCA is the previous crop addition (ex. 20 for soybean)PCA is the previous crop addition (ex. 20 for soybean)

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

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

Previous CropPrevious Crop Nitrogen Credit (lbs./acre) Nitrogen Credit (lbs./acre)

SoybeansSoybeans 10 10

Winter WheatWinter Wheat -10-10

CornCorn -10-10

MiloMilo -20-20

CottonCotton -10-10

RiceRice -20-20

Alfalfa (1/2 stand)Alfalfa (1/2 stand) 40 40

Previous CropPrevious Crop Nitrogen Credit (lbs./acre) Nitrogen Credit (lbs./acre)

SoybeansSoybeans 10 10

Winter WheatWinter Wheat -10-10

CornCorn -10-10

MiloMilo -20-20

CottonCotton -10-10

RiceRice -20-20

Alfalfa (1/2 stand)Alfalfa (1/2 stand) 40 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 What are the MFA and University of Missouri N Recommendations for a Missouri N Recommendations for a yield goal of 160 bu/A corn?yield goal of 160 bu/A corn?

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

Exactly the same: 200 lbs N/AExactly the same: 200 lbs N/AExactly the same: 200 lbs N/AExactly the same: 200 lbs N/A

Other Important N BMPs in MissouriOther Important N BMPs in MissouriOther Important N BMPs in MissouriOther Important N BMPs in Missouri

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

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

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

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

The preplant N test is advocated under certain The preplant N test is advocated under certain conditions:conditions:

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

• on fields that have a history of heavy manure applications. on fields that have a history of heavy manure applications. • following a drought year on fields with a high potential for carry following a drought year on fields with a high potential for carry

over for fertilizer N. over for fertilizer N. • following fall and early spring fertilizer applications where following fall and early spring fertilizer applications where

excessive rainfall may have caused losses of fertilizer N. excessive rainfall may have caused losses of fertilizer N.

The preplant N test is advocated under certain The preplant N test is advocated under certain conditions:conditions:

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

• on fields that have a history of heavy manure applications. on fields that have a history of heavy manure applications. • following a drought year on fields with a high potential for carry following a drought year on fields with a high potential for carry

over for fertilizer N. over for fertilizer N. • following fall and early spring fertilizer applications where following fall and early spring fertilizer applications where

excessive rainfall may have caused losses of fertilizer N. excessive rainfall may have caused losses of fertilizer N.

Other Important N BMPs in MissouriOther Important N BMPs in MissouriOther Important N BMPs in MissouriOther 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.

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

Nitrogen sourceNitrogen source Corn yieldCorn yield11

Ammonium nitrate (34-0-0)Ammonium nitrate (34-0-0) 149149

Urea (46-0-0)Urea (46-0-0) 142142

UAN solution (32-0-0)UAN solution (32-0-0) 13213211Average across 8 site years in MissouriAverage across 8 site years in Missouri

Other Important N BMPs in MissouriOther Important N BMPs in MissouriOther Important N BMPs in MissouriOther Important N BMPs in Missouri