Optimization of Winter Wheat Nutrition

The 2016-2017 season was the second experimental season under this project. Field experiments with winter wheat were again conducted at two locations having different soil types: Southern Chernozem (Haplic Chernozem Pachic) and Light Chestnut soil (Haplic Kastanozem Chromic). Both soils had a heavy texture, high pH, moderate organic matter (OM) content (3.8% and 1.8%, respectively), high nitrate-nitrogen (N) levels (31 to 87 ppm), medium concentrations of available phosphorus (P) (18 to 19 ppm P₂O₅), and medium and ‘increased’ concentrations of available potassium (K) (255 to 370 ppm K₂O) in the 0 to 20 cm soil layer. Available forms of P and K were extracted with ammonium carbonate solution.

The 2016-17 season had close to normal weather conditions. The best nutrient management practices in both locations included three sprays with potassium nitrate (PN): 1) 5% solution at tillering (2.4 kg N/ha and 8.1 kg K₂O/ha); 2) 3% solution at stem elongation (1.4 kg N/ha and 4.9 kg K₂O/ha); and 3) 3% solution at heading (1.4 kg N/ha and 4.9 kg K₂O/ha).

Both yield and quality of wheat grain were considerably improved compared to typical grower management practices for N, including ammonium nitrate (AN) topdressing in early spring at 34 kg N/ha. Grain yield was increased to 3.7 and 4.9 t/ha (Moisture content = 14%) or by 16 and 25% on the Chestnut soil and Chernozem, respectively. Grain protein concentration increased by 1% and gluten content improved by 2 to 3%. Grain quality thus matched the III class. A late-season application of urea at heading–flowering of 30 kg N/ha, in addition to AN topdressing in early spring, resulted in lower grain quality compared to foliar sprays with PN, especially without starter K fertilizer application on Southern Chernozem (4 N 16 P) were given at planting as monoammonium phosphate in 2016). Based on the two seasons of data available at this time, foliar fertilization with potassium nitrate seems to be a promising approach when growing winter wheat in Lower Volga. Nitrogen application is very minimal with these management practices.