Abstract
This experiment was conducted for two consecutive years 2000 and 2001 to study the effect of different levels of tillage and various combinations of cereal and legume residues on sorghum [Sorghum bicolor (L.) Moench). The experiment was laid out in a split-plot design with three replications. In both years of experimentation, surface mulching increased green as well as dry biomass production of sorghum in comparison to other mechanical treatments. Surface mulching and incorporation with tractor-drawn cultivator produced (significantly) maximum green fodder 22.7 t ha-1 (8.3 t ha-1 dry fodder) in 2000 and 23.7 t ha-1 green fodder (8.7 t ha-1 dry fodder) in 2001. A combination of 2 t ha-1 legume (Leucaena) dry litter + 40 kg N ha-1 through urea fertilizer produced significantly more green as well as dry fodder of sorghum. The organic C and total N per cent were increased in surface mulching, but the results were non-significant. However, application of cereal as well as legume residues significantly increased the organic C by 0.03% due to sole legume, 0.04% combined application, and 0.05% sole cereal application over the control. A similar trend in available N was observed. The microbial population, viz., bacteria, fungi, and actinomycetes were not influenced by any of the mechanical treatments. However, application of wheat as well as Leucaena litter residues significantly increased the microbial populations, i.e., 68-80% bacteria, 120-140% fungi, and 39-50% actinomycetes in two years of continued sorghum cultivation over the initial population. Maximum input energy was used in fertilizer and bio-residues and maximum output (151 200 MJ ha-1 in 2000 and 156 600 MJ ha-1 in 2001) as well as gross income ($5040 in 2000 and $5220 in 2001) in surface mulching incorporated by a tractor-drawn cultivator. Further, the application of 2 t ha-1 litter biomass of Leucaena + 40 kg ha-1 urea top-dressed in standing sorghum produced maximum output energy (163 800 MJ ha-1 in 2000 and 167 400 MJ ha-1 in 2001). This treatment also gave maximum income of $5460 ha-1 in 2000 and$5580 ha-1 in 2001.
