Impact of conservation agriculture practices on energy use efficiency and global warming potential in rainfed pigeonpea–castor systems

• Impact of conservation agriculture on energy use and GHG emissions were evaluated.
• Castor recorded higher energy use and energy use efficiency than pigeonpea.
• Zero tillage with 10 cm residue height recorded lowest energy input and GHG emissions.
• Fossil fuel contributed 24% of emissions in conventional tillage.
• In view of yield and environment, reduced tillage with 10 cm residue height is superior

Identification of agricultural practices which maximize crop productivity, energy use efficiency (EUE) and minimize greenhouse gas (GHG) emissions is essential. There is dearth of information in rainfed agriculture in general and conservation agriculture in particular, hence a study was conducted to assess the EUE and GHG emissions of different tillage practices like conventional tillage (CT), reduced tillage (RT) and zero tillage (ZT) and residue levels (harvesting heights resulting in 0, 10 and 30 cm anchored residue) in pigeonpea–castor systems under semi-arid rainfed regions of India. CT recorded 30 and 31% higher energy inputs than ZT in pigeonpea and castor, respectively. The fuel consumption in ZT was 58 and 81% lower than CT in pigeonpea and castor, respectively. This lower fuel consumption in ZT reduced the GHG emissions by 21 and 23% in pigeonpea and castor, respectively, in comparison with CT. EUE and energy productivity were maximum in ZT with 10 cm anchored residue. Further, castor grown on pigeonpea residue recorded 10 and 20% higher energy inputs and GHG emissions over pigeonpea grown on castor residues. Our results indicate that, reduction in one tillage operation with residue have a minimal impact on the crop yields but have a substantial environmental benefits.