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 MJ ha(-1)) and the lowest in soybean-chickpea (15672 +/- 26.29 MJ ha(-1)). Wheat, with the highest grain productivity, produced the most biomass energy (78541 +/- 28.75 MJ ha(-1)) and highest grain-energy productivity (0.150 kg MJ(-1)). The total bioenergy output of the crop production systems followed the order: soybean-wheat (131277 +/- 29.26 MJ ha(-1)) > soybean-mustard (101661 +/- 28.91 MJ ha(-1)) > soybean-chickpea (92658 +/- 28.87 MJ ha(-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 MJ t(-1) grain) followed by mustard (8912 MJ t(-1) seed), chickpea (7190 MJ t(-1) grain) and wheat (6646 MJ t(-1) grain) indicating that soybean is the most energy-investment intensive crop. Regarding energy intensiveness the results were contrary to EUE. Energy intensiveness (MJ Rs(-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. (C) 2002 Elsevier Science Ltd. All rights reserved.