Spring Wheat and Durum Fertilizer Recommendations

Revisions

Dave Franzen

Recommendations that are recent and that I am very confident about:

Canola, Flax, Barley, Sugarbeet, Dry beans

Recommendations that are out-of-date and I am not confident in them as currently written:

Wheat, corn, sunflower, most others

Several at NDSU have been working to update wheat N recommendations for five years.

I gathered all of our modern N calibration data (since 1970) along with recent and ongoing research. Here is what we have learned -

In the old days, we would add a regression line and a sill on the yield response for the state and call it good. The result of this exercise would look like this-

The “Return to N” model-

Developed by John Sawyer, Iowa State and Emerson Nafziger, Illinois (2005, Proc. Ext-Ind Soil Fert. Conf.)

This model is used in several corn-belt states, including Iowa, Illinois, Wisconsin, Minnesota, Ohio, Indiana and Michigan

Steps to implementation of Return to N-

-Generate yield response data -Use regression model from data to predict yield at N rates from 0 to maximum reasonable rate.-Generate gross return from each N rate-Generate cost of N from N rate- Subtract Cost of N from Gross return from N

Steps to implementation of Return to N in Wheat, or crops with quality factor-

-Generate yield response data -Use regression model from data to predict yield at N rates from 0 to maximum reasonable rate.-Generate quality response data-Use regression model to predict quality at N rates-Generate gross return from each N rate-Generate cost of N from N rate- Subtract Cost of N from Gross return from N

Langdon Region-Low = less than 40 bu/acreMedium = 41-60 bu/acreHigh = greater than 60 bu/acre

Eastern Region-Low= less than 40 bu/acreMedium=41-60 bu/acreHigh= greater than 60 bu/acre

Western Region-Low= less than 30 bu/acreMedium=31-50 bu/acreHigh=greater than 50 bu/acre

Effect of Tillage-

No-Till growers insist that after about 5 years, they can reduce their N rates substantially without harm.

Under No-till, the first 5 years it takes extra N (about 20 lb N extra)

After 5 years, can the rate be reduced?

N Costs cents per pound NWheat price 20 30 40 50 60 70 80 90 100

$3.00 100 80 70 60 50 45 40 0 0$4.00 105 95 85 75 65 55 45 30 30$5.00 110 100 90 80 70 60 50 40 60$6.00 115 110 105 100 95 90 85 80 60$7.00 115 110 105 100 95 90 85 80 60$8.00 115 110 105 100 95 90 85 80 60$9.00 115 110 105 100 95 90 85 80 65

$10.00 115 110 105 100 95 90 85 80 60

N rates, Western ND, Low Productivity

N Costs cents per pound N

Wheat price 20 30 40 50 60 70 80 90 100

$3.00 175 170 160 150 140 130 110 0 0$4.00 180 175 170 160 150 140 130 120 100$5.00 185 180 175 170 160 150 140 130 120$6.00 190 185 180 175 170 160 150 145 140$7.00 190 185 180 175 170 160 150 145 140$8.00 190 185 180 175 170 160 150 145 140$9.00 190 185 180 175 170 160 150 145 140

$10.00 190 185 180 175 170 160 150 145 140

N rates, Western ND, High Productivity

N Costs cents per pound NWheat price 20 30 40 50 60 70 80 90 100

$3.00 75 70 60 50 25 0 0 0 0$4.00 80 75 70 60 40 40 30 20 0$5.00 100 90 80 70 60 50 40 30 20$6.00 125 120 115 110 105 100 90 80 70$7.00 140 130 120 115 110 105 95 85 75$8.00 150 140 130 120 115 110 105 100 95$9.00 155 150 145 140 135 130 125 120 115

$10.00 160 155 150 145 140 135 130 125 120

N rates, Eastern ND, Low Productivity

N Costs cents per pound N

Wheat price 20 30 40 50 60 70 80 90 100

$3.00 200 190 175 150 125 60 0 0 0$4.00 250 235 220 200 180 160 120 100 0$5.00 250 235 220 200 190 180 160 140 120$6.00 250 250 225 210 200 190 180 160 150$7.00 250 250 250 240 220 200 190 180 175$8.00 250 250 250 250 225 210 200 190 180$9.00 250 250 250 250 250 220 210 200 190

$10.00 250 250 250 250 250 240 230 220 200

N rates, Eastern ND, High Productivity

There is ample evidence that within a region an organic matter adjustment to make between fields or within fields may be justified.

We are planning a series of experiments state-wide in 2009 that will address that question.

After those experiments are completed, the new recommendations will be formulated.

Other changes- Phosphorus-

Potassium recommendations-Soil test K > 100 ppm, no additional K

required. KCl (0-0-60-50Cl) may be applied

if Cl levels are low.

Soil test K 100 ppm or less, apply 50 lb/acre KCl (25 lb/acre K2O)