With winter wheat planting drawing near, this is a good time to collect soil samples to determine fertilizer needs for this fall and next year.

Available soil water varies across wheat-growing regions in Nebraska this year 9 (see chart below), which will affect yield potential. Land with higher precipitation may have had nitrogen move deeper in the soil profile. It is recommended to collect soil samples to at least a 3-foot depth before sowing the wheat crop to determine residual nitrate-N and adjust N recommendations.

Detailed information on soil sampling can be found in Guidelines for Soil Sampling, NebGuide G1740, and Soil Sampling for Precision Agriculture, EC154.

Departure from normal precipitation (inches): Aug 29, 2016 – Aug 28, 2017. (Source: NOAA Regional Climate Centers)

Profitable winter wheat production often requires N and phosphorus fertilization. Most Nebraska soils supply adequate nutrients other than N and P.

Nitrogen
Soil test results, fertilizer prices and expected selling price for wheat are used to calculate both N and P recommendations. As wheat and fertilizer prices can change, a safe approach is to apply a small amount of N (20 pounds of N per acre) this fall, either row-applied or broadcast. Use soil test results, and watch fertilizer and wheat prices over the fall and winter to determine how much additional N might be applied next spring before jointing. Based on a range of current prices for wheat and nitrogen (Table 1), it is still profitable to apply N.

Phosphorus
Nebraska data shows up to a 20-bushel-per-acre increase when applying P to low soil test levels  and up to a 10-bushel-per-acre increase when applying to medium P soils. The most profitable rate depends on the P source, wheat and fertilizer prices, soil pH, and the application method. With row or dual-applied P, the P rate can be reduced by 50% compared with broadcast.

Dual-applied P and seed-applied (row) P perform equally at optimum seeding dates (see recommended dates). Phosphorus recommendations in wheat depend on several factors. All information needed to determine P rates as well as example calculations are provided in Fertilizing Winter Wheat, UNL EC143.

This report comes from UNL CropWatch.