Global Maize Project in India: Dharwad, Karnataka - Site Specific Nutrient Management in Maize-Wheat cropping system in Northern Karnataka

Long-term evaluation of ecological intensification (EI) and farmer's practice (FP) in the maize-wheat cropping system during the fourth year of experimentation revealed that the grain and stover yields of maize in EI were 6.5 and 8.3 t/ha, which were 20 and 16% higher than the yields obtained in FP, respectively. Compared to the previous year, the grain yield under EI improved by 2.5 t/ha (64% increase) in 2013. Pooled data for four years indicated 27% higher grain yield in EI than in FP, which was 3% higher than the previous year. The higher grain yield in EI treatment over FP may be attributed to higher nutrient uptake of N (121 kg/ha), P (49 kg/ha) and K (41 kg/ha) in EI, which were 40, 27 and 26.5% higher than in the FP, respectively. Also, net returns of INR 34,472/ha were obtained in the EI treatment, which were 29% higher than the net returns obtained with FP (INR 26,830/ha), an improvement over the previous year by 3%. In wheat, higher grain and straw yields of 3.5 and 6.6 t/ha were reported in EI treatment, which were 17 and 5% higher than the grain and straw yields recorded in FP, respectively. Considering the maize equivalent yield for wheat, pooled data averaged over four years indicated that EI could result in a higher maize grain yield of 9.8 t/ha with application of 310 kg N, 160 kg P₂O₅ and 160 kg K₂O, which was 22% higher than the yield obtained in the FP treatment with application of 185 kg N, 103 kg P₂O₅ and 105 kg K₂O, respectively.

Rate and application studies pooled over four years found that 240 kg N/ha application could generate 6.9 t/ha maize, which was higher than the 6.1 t/ha produced with 160 kg N/ha. Net returns (and B:C ratios) with 240 and 160 kg N/ha were INR 52,305 (3.83) and 46,179 (3.70), respectively. Application of N in three splits with and without the use of leaf color charts (LCC) resulted in equivalent maize yields of 4.9 and 4.8 t/ha, but these results were superior to N applied in two splits. Similarly, grain yields pooled over four years in the succeeding wheat crop were 3.8 and 3.3 t/ha with 150 and 100 kg N/ha applications, respectively. Application of N in three splits with and without the use of leaf color charts (LCC) resulted in equivalent wheat yields of 2.8 t/ha. However, the results were superior to N provided in two splits, which recorded a grain yield of 2.6 t/ha, respectively. The data generated in this project so far has helped to provide 4R strategies of nutrient management in the maize-wheat cropping system for the benefit of the farmers of Karnataka.