Conservation Tillage Enhances Energy Efficiency and Mitigates Carbon Footprint and Greenhouse Gas Emissions in Long-Term Wheat Production Trials in the Western Indo-Gangetic Plain of India

Traditional rice and wheat cropping system (RWCS) of the western Indo-Gangetic Plains (IGP) is not only less productive, but also unsustainable owing to its elevated energy demands and environmental carbon footprint. Transition towards the long-term adoption of conservation agriculture (CA) technologies can possibility overcomes these constraints and making it a crucial component of modern farming systems. Therefore, the effects of conservation tillage and residue retention on wheat cultivation were evaluated from 2015-2016 to 2019-2020 under RWCS on CA fields maintained for twenty one years. Five tillage treatments viz., zero tillage without residue retention (ZT-R), zero tillage with residue retention (ZT+R), permanent bed planting without residue retention (PBP-R), rotary tillage without residue retention (RT-R) and conventional tillage without residue retention (CT-R) were evaluated in four times replicated randomised complete block design. The CT-R recorded 28%, 25%, 24%, and 16% higher energy inputs than those of the ZT+R, ZT-R, PRB-R, and RT-R, respectively. Nevertheless, the lowest grain energy output was recorded in RT-R (86,769 MJ ha-1) and CT-R (86,926 MJ ha-1). Under CT-R, greenhouse gas (GHG) emissions were approximately 20%, 19%, 17%, and 10% greater than those under ZT-R, ZT+R, PRB-R, and RT-R, respectively. Compared to ZT-R, ZT+R, PRB-R, and RT-R plots, CT-R exhibited significantly lower carbon efficiency ratio and carbon sustainability index. The long-term study revealed that ZT+R represent a promising step towards sustainability, characterized by low global warming potential and high energy use efficiency. This makes it an appealing agricultural technique for wheat production in the sub-tropical IGP regions under irrigated RWCS.