Split application of organic nutrient improved productivity, nutritional quality and economics of rice-chickpea cropping system in lateritic soil

Sustainable food production to meet the demand of increasing population is a challenge as the yield is stagnant or under decline in intensive chemical farming. As a part of long-term nutrient management trial initiated in 2009, field experiments were conducted to study the effect of varying amounts and timing of application of different organic and inorganic nutrient sources on productivity and quality of crops in rice-chickpea cropping system under lateritic belt of sub-tropical India. The organic nutrient sources were vermicompost (VC), vermiwash (VW), crop residue (CR), and Azotobacter (AZ) and the inorganic source was chemical fertilizer (CF). The nutrient management treatments were Control (no fertilizer application), CF at 100% recommended dose of N, P and K (CF100), VC at 100%N recommendation as basal application (VC-b100), VC at 100%N recommendation in two splits (VC100), VC50 + CF50, CR, CF50 + CR, VC50 + CR and VC50 + VW + AZ. Effect of direct application of these nutrient treatments was studied on rice crop grown in wet season (June-October) and their residual effect was assessed on chickpea grown in dry season (November-March) in the cropping system during 2013-2015 at Kharagpur, India. The split application of VC (VC100) to rice gave comparable grain yield of CF100. However, the VC100 had profound residual effect on succeeding chickpea crop in increasing its seed yield significantly, thereby productivity of the rice-chickpea system. This resulted the VC100 in realising higher net return (29%), benefit-cost ratio, net energy (22%), and energy ratio as compared to CF100 in the cropping system. Further, the VC-based treatments increased micro-nutrients (Fe, Mn and Zn) content in soil resulting improved quality of rice grain. At the end of two-years cropping, significantly higher available soil N content was noted with VC100 as compared to rest treatments. Split application of organic fertilizer was effective in increasing productivity, economics, and energy efficiency of the rice-chickpea cropping system.