Carbon sequestration and soil health dynamics in Zero-Till Rabi systems after varying rice residue loads

Abstract

The rice-based cropping system, a cornerstone of global food security, faces severe sustainability crises due to intensive soil inversion, declining water tables and the environmental menace of residue burning. This review critically evaluates the interplay between rice phenology categorized into short, medium and long-duration varieties and the resultant residue loads that dictate the success of zero tillage rabi systems. While long-duration varieties contribute substantial biomass (7-11 t ha-1) conducive to long-term carbon sequestration and soil thermal insulation, they present significant mechanical impediments to precision sowing. Conversely, short-duration varieties facilitate timely rabi sowing, effectively mitigating terminal heat stress, yet often fail to provide the critical threshold of mulch required for effective moisture conservation. Synthesizing global meta-analyses, this paper highlights that zero tillage with optimal residue retention can enhance soil organic carbon by 14.8-39.4% and significantly augment microbial biomass carbon and enzymatic activities (e.g., dehydrogenase and phosphatase).