Effects of organic manures and chemical fertilizers on productivity and profitability in wheat - rice cropping sequence

A field experiment was conducted to study the effect of organic manures and chemical fertilizers on wheat - rice crop sequence with five sources of organic manures and three chemical fertilizer levels (50, 100 and 150 per cent of recommended NPK 120 kg N + 60 kg P2O5 + 30 kg K2O) in wheat along with one control. Rice was grown with 100 per cent of recommended NPK fertilizers 90 kg N + 40 kg P2O5 + 40 kg K2O except absolute control to study the residual effect of organic manures and chemical fertilizers supplied to preceding wheat crop on yield attributes and yield of succeeding rice crop. Yield attributes, grain yield and harvest index of both wheat and rice as well as cropping system as a whole improved significantly in FYM supplied plots @ 10 t ha-1 followed by berseem 'in situ' green manuring + FYM, mushroom spent compost + FYM, mushroom spent compost and berseem 'in situ' green manuring, respectively during the study. Net returns in wheat and rice crops as well as system as a whole, were again found to be significantly highest with the application of FYM at 10 t ha-1. A consistent and significant improvement in yield attributes, yield, harvest index, net returns and benefit: cost ratio of wheat and rice crops were observed with increase in chemical fertilizer levels from 50 to 150 per cent of recommended NPK. System productivity and profitability also followed the similar trend as that of grain yield in wheat and rice crops with the application of chemical fertilizers.