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.