This article was authored by Ron Gelderman, former Professor & SDSU Extension Soils Specialist.
Winter wheat seeding is just around the corner and fertilization plans are being considered, including starter fertilizers. A starter fertilizer is a band of fertilizer applied near the seed – usually at planting. Phosphorus (P) is the most common nutrient applied as a band application with or near the seed. Phosphorus applied near the seed will often produce a more vigorous plant and root system, leading to less winter injury and better stands in the spring, especially on medium or low P testing soils. A good winter wheat crop will need from 50 to 65 lb./A of phosphate either from the soil and/or fertilizer sources. This amount of P can be applied as a starter on fine to medium textured soils that are moist at planting without fear of seedling injury. Other nutrients considered for starter applications include nitrogen (N), sulfur (S) and chloride (Cl).
Nitrogen is not needed in large amounts for the winter wheat fall growth. Typically, residual nitrate-N, mineralized N, and N applied with phosphorus are more than sufficient to meet fall growth needs.
Sulfur application, as with other nutrients, should be based on a soil test. South Dakota State University recommendations for S are based on soil texture, tillage practices and soil test levels to two feet. For a good wheat crop, only 15 to 20 lbs. of S are taken up and most of this is during the rapid growth phase in the spring. Sulfur applied with a starter is of limited use until spring. Starter applications of S as ammonium sulfate or other sources may lead to decreased P starter rates of DAP (18-46-0) or MAP (11-52-0) as all fertilizers are salts and can cause germination injury. Therefore it may be more prudent to apply any S needs with spring N applications.
Chloride is a needed nutrient that has been shown to reduce many leaf diseases. Rates of chloride are based on a two foot soil test as are N and S. The most economical source of chloride is potassium chloride (0-0-60). This fertilizer can also produce significant injury if applied with the seed at rates that are commonly recommended in South Dakota. Therefore chloride application can be delayed until spring as well.
The bottom-line? Starter applications should contain P as the predominant nutrient needed for vigorous fall growth of winter wheat. Other needed nutrients can be applied with spring N applications.
Click on “Fertilizer Decision Aid” at the SDSU Soil Fertility website to determine the fertilizer rate that can safely be applied with wheat planting.