Energy auditing of long-term conservation agriculture based irrigated intensive maize systems in semi-arid tropics of India

In a 7-year study, we assessed the conservation agriculture (CA) practices [permanent bed (PB) and zero tillage (ZT)] and conventional till (CT) in 4-diversified maize rotations [maize-wheat-mungbean (MWMb), maize-chickpea-Sesbania green manure (MCS), maize-mustard-mungbean (MMuMb) and maize-maize-Sesbania green manure (MMS)]. Results showed that ZT and PB plots consumed lower energy (7 yr average) in land preparation (49.7-51.5%) and irrigation (16.8-22.9%) compared to CT. Significantly higher system output (10.6-14.5%) and net energy (14.8-18.9%) returns, biomass productivity (9.9-14.1%), energy use-efficiency (13.4-17.1%), and bio-energetic based adult equivalent yield (17.3-19.8%) was recorded in ZT and PB than the CT. Among the crop rotation plots the net energy-output (35,3346 MJ ha−1), biomass yield (11.87 Mg ha−1), energy use efficiency (4.16), and bio-energetic based adult equivalent yield (46 adults ha−1 year−1) was recorded significantly (P ≤ 0.05) higher in MWMb plots. Interaction between tillage and crop rotations were significant (P ≤ 0.05) for mean system output and net energy returns, biomass productivity and bio-energetic based adult equivalent yield. Thus, our long-term study suggests that CA practices with diversified maize based rotation (MWMb) could be a feasible alternative to attain high energy-use efficiency, biomass productivity and bio-energetic based adult equivalent yield in north-western India and other similar agro-ecologies of South Asia.