Improving nutrient use efficiency and profitability in rainfed production systems

A study was conducted to determine the effect of balanced nutrient use and conservation tillage on productivity, profitability and nutrient use efficiency in a maize-horsegram cropping sequence. Data revealed highest maize grain (4.7 t/ha) and stover (7.9 t/ha) yields with the optimum nutrient treatment, followed by yields under B omission (4.4 and 6.9 t/ha), S omission (4.2 and 7.2 t/ha), while the lowest productivity was observed in the control plot (1.3 and 3.5 t/ha). No significant difference in grain and stover yield of maize was observed among the tillage systems. In horsegram, yields varied significantly from 264 to 443 kg/ha in the conventional tillage (CNT) system with highest yield recorded in S omission plot (443 kg/ha) followed by optimum treatment (418 kg/ha). In the conservation tillage (CST) system, yields were in the range of 464 to 643 kg/ha, with optimum treatment showing a lower yield (578 kg/ha) as compared to yields obtained with omission of S (643 kg/ha), P (635 kg/ha), N (618 kg/ha), and Zn (596 kg/ha). The lowest yield was again recorded in the absolute control treatment (464 kg/ha). The higher yield in CST could be attributed to high nutrient uptake in this system. In CST, N, P and K contents in horsegram seed were in the range of 1.6 to 2.6, 0.2 to 0.7, and 0.8 to 1.2% across different nutrient treatments, whereas, the corresponding values in CNT were 1.5 to 2.5, 0.2 to 0.6, and 0.7 to 1.0%, respectively.

Initial soil reaction (pH) of 5.1 increased to 5.6 after the harvest of horsegram in both the tillage systems, whereas the initial soil organic carbon of 0.34% increased slightly to 0.43% in the CNT and to 0.41% in the CST treatment. Optimum nutrient treatment had the highest residue cover (45%) followed by omission of Zn (42%), K and S (41%), and B (40%) with the least residue cover noticed in absolute control plot (31%). Also, N, P, K, S, and Zn efficiencies were increased to 11, 16, 14, 13, and 21% due to integrated effect of balanced nutrient use coupled with conservation tillage. Higher net returns (INR 26,571/ha) and benefit:cost ratio (2:1) were noticed in optimum nutrient treatment under CST as compared to INR 22,529/ha and 1.9, respectively, under CNT. Practicing CST with better nutrient management improved nutrient use efficiency and increased productivity and profitability of farmers in this semiarid tropical area. Funding for this project was completed in 2012, and final results are expected by mid-2013. India-014