Improvement of Maize and Soybean (Chickpea) Mineral Nutrition on a Calcareous Common Chernozem

The 2015 maize season in southern Russia was characterized by delayed planting because of cool, rainy weather conditions during the first half of May. Thus, a summer drought that typically begins in the second part of July and continues in August negatively affected pollination and grain filling of maize. Grower’s fertilizer practice and the Ecological Intensification (EI) management system were compared at the A-site. Two maize hybrids with differing days to maturity (i.e., Furio = 115 to 120 days; P9025 = 124 days) were grown under grower’s practice and EI. Grower’s practice (30 kg N/ha and 40 kg P₂O₅/ha) yielded only 3.0 t/ha in 2015 and the omission of N (decreasing N rate from 30 to 9 kg/ha) caused a significant (11%) yield loss. There was no zero N treatment because monoammonium phosphate was used as a source of P in field experiments. The EI treatment (85 kg N/ha, 70 kg P₂O₅/ha and 40 kg K₂O/ha) yielded 3.7 t/ha, giving a significant (25%) increase over grower’s practice. The EI management system also included a Zn seed treatment. Omission of N from the EI system (decreasing N rate from 85 to 17 kg/ha) caused a significant yield decrease to 3.46 t/ha.

Soil nitrate concentrations (0 to 20 cm) at the C-site prior to planting were low (8 ppm) with 20 ppm ammonium-N, and very high concentrations of of Olsen-extractable P and exchangeable K (17 ppm and 390 ppm, respectively). Maize (P9025 hybrid) followed winter wheat and had practically the same productivity compared to the A-site. A yield of 2.85 t/ha was obtained in the control treatment (zero fertilizer), and grower’s practice (30 kg N/ha and 40 kg P₂O₅/ha) resulted in a significant (7%) increase over the control. The highest yield of 3.7 t/ha was achieved with ample NPК rates (100 kg N/ha, 80 kg P₂O₅/ha and 60 kg K₂O/ha) giving 29% more that the control and 21% more than grower’s practice. Omission of N (decreasing N rate from 100 to 18 kg/ha), P, and K resulted in significant yield decreases of 12%, 10%, and 5%, respectively. Broadcasting K fertilizer at an application rate of 60 kg K₂O/ha had practically the same effectiveness as a starter application at 30 kg K₂O/ha. There was no significant difference between these two treatments. Sulfur application was not effective at boosting yields in the 2015 maize season.