ENERGY-USE PATTERNS IN SUBTROPICAL RICE-WHEAT CROPPING UNDER SHORT-TERM APPLICATION OF CROP RESIDUE AND FERTILIZER

Rice-wheat cropping in the sub-tropics is energy intensive, requiring a major input from fossil fuel. These crops produce lots of residue, p art of which is often wasted in burning, the incorporation of which is beneficial when applied with fertilizer. Reserves of fossil fuel is d ecreasing at an increasing rate. Therefore, it is more important to kn ow the effect of application of residue production from these crops in the light of recycling of energy and its output. Keeping this in view in a field experiment between 1990 and 1992, three levels of residue incorporation: (i) nil, (ii) half, (iii) full of residue production fr om one crop to the other were combined with two levels of mineral fert ilizer: (i) no fertilizer, (ii) standard level of 120, 60, 60 kg N, P2 O5 and K2O per hectare as treatments. The trade-off studies showed tha t applications of half the crop residue with fertilizer consistently p roduced the highest grain yield of rice and wheat. Addition of residue without fertilizer had little benefit while application of fertilizer without residue had moderate effects. The combined application of hal f the residue with fertilizer proved to be the best combination provid ing the maximum production of crop per unit use of fossil fuel. The hi ghest labour productivity (crop production/hour of labour) was also fo und under the same treatment. But further addition of residue with fer tilizer declined the crop production per unit area, per unit of fossil fuel or per hour of labour. So keeping in view the fast depleting com mercial energy sources, incorporating half the residue production of t he crop with recommended fertilizer in a rice-wheat cropping may be a wise practice in solving the energy problem for higher production in t his part of the subtropics.