Optimization of Winter Wheat Nutrition

Field experiments were initiated in the fall, 2015. One field location had a Southern Chernozem soil and the other had a with light Chestnut soil. Both soils had a heavy texture, high pH, low organic matter (1.8 to 3.4 %), elevated nitrate concentrations, medium or ‘increased’ P concentrations (28 to 32 ppm P₂O₅) and ‘increased’ and high K concentrations (392 to 420 ppm K₂O) in the 0 to 20 cm soil depth.

Both the spring and summer period in 2016 had much higher precipitation compared to the long-term average. The experimental treatments in both locations included two sprays with potassium nitrate, (i.e., 7 % solution at tillering (3.4 kg N and 11.3 kg K₂O per ha) and 5% solution at stem elongation (2.4 kg N and 8.1 kg K₂O per ha). The yield and quality of wheat grain were considerably improved compared to typical grower management practices for N by including ammonium nitrate (AN) topdressing in early spring at 34 kg N/ha. Grain yield was increased by 7 and 12% (to 4.6 and 5.8 t/ha) on Chestnut soil and Chernozem, respectively. Grain protein concentration increased by 1 to 2 % and gluten content improved by 3 to 4 %. As a result, grain quality level was improved from IV class (feed grain) to III class (food grain) in both locations.

Late season application of 30 kg N/ha as urea at heading–flowering (in addition to AN top-dressing) resulted in lower grain quality compared to foliar sprays with potassium nitrate. Food grain (III class) was achieved with a late season application of urea only on the Chestnut soil. Based on these first season results, foliar fertilization with potassium nitrate may be a promising management approach when growing winter wheat in the Lower Volga area.