Bioenergy and economic analysis of soybean-based crop production systems in central India

The study examines the energy requirement and energy input–output relationship of soybean-based crop production systems viz., soybean (Glycine max (L.) Merr.)–wheat (Triticum aestivum L.), soybean–mustard (Brassica juncea (L.) Czern & Coss.) and soybean–chickpea (Cicer arietinum L.) in central India. Using a pre-tested questionnaire, 135 farmers were selected through a multi-stage stratified random sampling technique. Results revealed that manures and chemical fertilizers (50.87%), seedbed preparation (18.30%) and sowing management (17.69%) consumed the bulk of the energy (operational and non-operational) for all crops, it was highest in soybean–wheat (23705±29.48 MJha−1) and the lowest in soybean–chickpea (15672±26.29 MJha−1). Wheat, with the highest grain productivity, produced the most biomass energy (78541±28.75 MJha−1) and highest grain-energy productivity (0.150 kgMJ−1). The total bioenergy output of the crop production systems followed the order: soybean–wheat (131277±29.26 MJha−1) > soybean–mustard (101661±28.91 MJha−1) > soybean–chickpea (92658±28.87 MJha−1). But this order was reversed for energy-use efficiency (EUE): soybean–chickpea (5.91)> soybean–mustard (5.86)> soybean–wheat (5.54). Specific energy was highest in soybean (9173 MJt−1 grain) followed by mustard (8912 MJt−1 seed), chickpea (7190 MJt−1 grain) and wheat (6646 MJt−1 grain) indicating that soybean is the most energy-investment intensive crop. Regarding energy intensiveness the results were contrary to EUE. Energy intensiveness (MJRs−1) was higher in wheat (1.40) followed by mustard (1.11), soybean (0.89) and chickpea (0.87) and the soybean–wheat system (1.13) emerged as the most energy-intensive system compared to soybean–mustard (0.97) and soybean–chickpea (0.88). Though the net return from soybean–wheat was marginally higher than other systems, the soybean–chickpea system is more suitable in the central ecological niche of India due to its low requirement for non-renewable resources, higher EUE and benefit–cost ratio.