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

Farmer fertilizer practice (FP) and the Ecological Intensification (EI) management system were studied at the A-site of the Global Maize project. Two different maize hybrids (Krasnodarskiy 291-FP and P9175-EI) were grown in 2017 under these crop management systems. The 2017 season had near normal weather conditions.

FP resulted in a maize yield of 6.3 t/ha (Moisture content = 15.5%) and the omission of nitrogen (N) (i.e., decreasing N rate from 30 to 9 kg/ha) caused a yield loss of only 2%. A maize yield of 7.1 t/ha was obtained in the EI treatment giving a considerable increase over FP (by 13%). The omission of N from the EI system (decreasing N from 85 to 17 kg/ha) caused a significant yield decline to 6.6 t/ha. For chickpea, FP had a yield of 2.6 t/ha (Moisture = 13%) and the addition of N (i.e., increasing N rate from 6 to 24 kg/ha), resulted in a non-significant yield increase by 1%. Seed yield of 3.0 t/ha was obtained with a moderate N fertilization rate of 24 kg/ha in the EI treatment, a considerable improvement over FP (by 16%). The omission of N in the EI system (i.e., decreasing N rate from 24 to 12 kg/ha) caused a statistically non-significant yield decline to 2.9 t/ha.

Prior to planting maize at the C-site, the soil had a low nitrate (NO₃)-N concentration of 6 ppm, a NH₄-N concentration of 6 ppm, high level of Olsen-extractable phosphorus (P) (15 ppm), very high level of exchangeable potassium (K) (353 ppm), low level of available sulfur (S) (4 ppm) routinely extracted with 1M potassium chloride (KCl) solution in the 0 to 20 cm layer. Fertilizer treatments (kg/ha) at the C-site in 2017 included: 1) 30N 40P (Grower Practice); 2) N40N 70P 60K; 3) 60N 70P 60K; 4) 80N 70P 60K; 5) 100N 70P 60K; 6) 80N 70P 60K 7S 0.5Zn; and 7) 80N 70P 60K 10S Zn1.

The N application rate of 80 kg/ha was found to be agronomically optimum during the second season, but the yield response to increasing N rates was low (by 6% compared to 40 kg N/ha). The highest grain yield of 6.25 t/ha was obtained in treatment seven, receiving 80 kg N, 70 kg P₂O₅, 60 kg K₂O, 10 kg S, and 1 kg Zn/ha. A yield increase over the Grower Practice reached 17%. Sulfur and Zn-containing fertilizers (NPSZn 16-34-6-0.4 and 12-40-10-1) applied at planting provided a yield improvement of 4%.