Potential of Modified Reduced Tillage with Cover/Green Manure Crop for Climate Change Mitigation in a Smallholder Rainfed Farming System

Abstract

Soil can function as a reservoir and a source of greenhouse gases (GHGs), contingent on its management. This study assesses the potential of a modified reduced tillage (MRT) approach involving the use of cover or green manure crops as a substitute for crop residues to mitigate GHG emissions from soil within smallholder rainfed farming systems. A two-year field experiment with different tillage techniques (moldboard plow, tine cultivator, and modified reduced tillage) and crop rotations (summer fallow–wheat and cover/green manure–wheat) was conducted at Rawalpindi, Pakistan. The results showed that MRT reduced carbon dioxide (CO2) and nitrous oxide (N2O) emissions by 8% and 15.3%, respectively, from soil while maintaining consistently higher soil moisture than conventional tillage techniques. The modified reduced tillage reduced the global warming potential (GWP) and greenhouse gas intensity (GHGI) by 15.8% and 20.7%, respectively. The net ecosystem exchange (NEE) was unaffected by the tillage systems. Therefore, adopting the MRT technique and incorporating green manure is a viable strategy for curtailing GHG emissions from soil, particularly in the context of smallholder rainfed farming systems. Extended, multi-year studies under various climate scenarios and agronomic practices are needed to understand the long-term impacts of MRT and crop rotations on GHG emissions.