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

Limited rainfall patterns prevailed in the experimental area during July – August, 2012 had a negative effect on crop production. There was about 17% and 30 % yield reduction, respectively, in maize and soybean compared to the previous season. Maize at the A-site was grown after soybean harvested in 2011 in early October. Maize at the C-site was practically grown after summer fallow because of early winter wheat harvest 2011 (mid-June) that may explain slightly higher maize yields at the C-site. Grower fertilizer practice for maize (30 N 40 P) gave 6.76 t/ha grain at the A-site and “omission” of N fertilizer (9 N 40 P) resulted in 6.70 t/ha, i.e. there was no significant difference between these treatments. No real zero N plots were tested since monoammonium phosphate (MAP) was used as a source of P. Ecological Intensification (EI) for maize (85 N 70 P 40 K) gave 7.33 t/ha, and “omission” of N (17 N 70 P 40 K) resulted in 6.98 t/ha. Grower fertilizer practice for soybean (20 N 40 P) gave 1.31 t/ha at the A-site, and “omission” of N fertilizer (9 N 40 P) produced slightly less yield of 1.25 t/ha. In soybean, EI (30 N 45 P 30 K) gave 1.55 t/ha, while “omission” of N (10 N 45 P 30 K) led to nonsignificant yield reduction by 0.05 t/ha. Ecological Intensification for soybean resulted in higher protein content in grain (38.9%) compared with N “omission” (37.8%) – generating a maximum protein output of 524 kg/ha.

The highest yield of maize at the C-site (7.50 t/ha) was obtained with ample NPK rates (100 N 80 P 60 K) and the control treatment gave 6.61 t/ha. Thus, maize yield increased by 13% due to mineral fertilizer application. Nitrogen, P, and K fertilizer use at the C-site increased grain yield by 0.61 t/ha (9%), 0.33 t/ha (5%), and 0.12 t/ha (2%), respectively. The response to K fertilizer application was nonsignificant compared to the previous season. Initial soil properties at the C-site indicate medium nitrate level in the soil (11.8 ppm), medium content of P extracted with (NH₄)₂CO₃ solution (9.6 ppm P) but “increased” level of Olsen P (17 ppm P) according to soil-test interpretation classes proposed by researchers in Russia. The content of K extracted with (NH₄)₂CO₃ solution indicates high soil-test K class (271 ppm K), and the exch. K level in the soil was very high (375 ppm K). IPNI-41