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

Maize was grown in 2011 after winter wheat at both the A-site and C-site. The potential yield was determined at the A-site, and thus the respective yield gap. We accessed what practices and inputs needed to be modified to narrow the yield gap. The current grower practice and the Ecological Intensification (EI) management system were compared for the site. On-farm experiments (C-site) were used to facilitate fine-tuning of the management systems and getting them in place on farmers’ fields. Initial soil properties indicate substantial soil nitrate (14.1 to 14.6 ppm in 0 to 20 cm layer), medium P extracted by a routine soil test (1% (NH₄)₂CO₃)—or “increased” (16 ppm P) according to new Olsen P soil-test interpretation classes proposed by researchers in Russia. The content of K extracted by 1% (NH₄)₂CO₃ was considered high, and the exchangeable K level was very high (373 to 387 ppm).

Grower fertilizer practice for maize (30 N 40 P) gave 8.12 t/ha grain at the A-site and “omission” of N fertilizer (9 N 40 P) resulted in 7.78 t/ha. No real zero N plots were tested since monoammonium phosphate (MAP) was used as a source of P. Ecological Intensification (EI) for maize (80 N 70 P 40 K) gave 8.77 t/ha, and “omission” of N (12 N 70 P 40 K) resulted in 8.33 t/ha. Grower fertilizer practice for soybean (20 N 40 P) gave 1.92 t/ha at the A-site, and “omission” of N fertilizer (9 N 40 P) produced 1.86 t/ha. In soybean, EI (30 N 45 P 30 K) gave 2.27 t/ha, while “omission” of N (10 N 45 P 30 K) led to 2.12 t/ha. Ecological Intensification for soybean also resulted in higher protein content in grain (46.7%) compared with N “omission”(43.9%)—generating a maximum protein output of 1,060 kg/ha. The highest yield of maize at the C-site (8.98 t/ha) was obtained with ample NPK rates (100 N 80 P 60 K) and the control treatment gave 7.45 t/ha. Thus, maize yield increased by 21% due to mineral fertilizer application. Nitrogen, P, and K fertilizer use at the C-site increased grain yield by 0.69 t/ha (8%), 1.05 t/ha (13%), and 0.56 t/ha (7%), respectively. Response to K fertilizer application indicates that perhaps soil-test K interpretation classes need to be adjusted and updated. IPNI-41