Energy requirement of different weed management practices for aerobic rice in India

An analysis of the energy requirements for the rice (Oryza sativa L.) was conducted at the Research farm of Project Directorate for Cropping Systems research, Modipuram, Meerut during the year of 2000-01 to 2003-04. Selected weed management practices: hand weeding twice, herbicides + one hand weeding, criss-cross sowing + one hand weeding, criss-cross sowing + herbicides + one hand weeding, unweeded check were subjected to aerobic rice crop to assess the energy use, out put energy obtained and net return of energy. Results revealed that the total input energy utilization in rice varied from 31,230.6 MJ/ha to 32,252.3 MJ/ha in unweeded check and criss-cross + herbicides + hand weeding, respectively. The energy use by irrigation represented the major part of total energy use, accounting about 47.6 percent followed by fertilizers about 32 percent in all treatments, where-as, machinery consumed from 11.5 to 12.5 percent of total input energy. Total amount of energy use in weed management varied from 1.18 to 2.88 percent of the total input energy. Hand weeding twice was more energy consuming than other treatments. This was followed by herbicides + hand weeding once as well as criss-cross sowing + herbicides + hand weeding once. The energy utilization for weed management was slightly higher in traditional seedbed as compared with stale seedbed. The output energy in criss-cross sowing + herbicides + hand weeding once was from 83 to 89 percent higher than unweeded, 55 percent higher than criss-cross sowing + hand weeding once, from 9 to 13 percent higher than hand weeding twice and 4 percent higher than herbicides + hand weeding once. The net return energy, among five treatments, was found to be significantly high in criss-cross sowing + herbicides + hand weeding once (i.e. 51,043.5 MJ/ha in stale seedbed and 44,363.7 MJ/ha in traditional seedbed) than other treatments, which was statistically at par with treatment herbicides + hand weeding once (i.e. 47,789.6 MJ/ha in stale seedbed and 44,847.2 MJ/ha in traditional seedbed). This was followed by hand weeding twice (i.e. 40,806.6 MJ/ha in stale seedbed and 37,591.5 MJ/ha in traditional seedbed) and criss-cross sowing + hand weeding once (i.e. 6,214.9 MJ/ha in stale seedbed and 1,534.2 MJ/ha in traditional seedbed) which had significant difference in the same seedbed preparation. However, the unweeded treatment gave negative net return energy. So, without weed management, practices adopted will not able to get output energy.