Synchronizing the residue decomposition dynamics and nitrogen release from the litterbags study of a maize-wheat rotation under the decade-long integrated crop management practices.

Abstract

Decomposition of crop residues plays a vital role in carbon (c)- and nitrogen (N)- cycling. This study assessed the decomposition and N-release dynamics of maize and wheat residues using a nylon mesh-bag method under eight integrated crop management practices (ICMPs) in a long-term (2014-24) maize-wheat cropping rotation. In the CA-based ICMPs:_5-8, maize residues were surface-retained, while in the CT-based ICMPs:_1-4, the residues were incorporated. Residue decomposition and N-release followed first-order kinetics, modeled using accumulated thermal time (ATT). At 150 days (2736 °C ATT), CA-based plots retained 56.3-71.4% (maize) and 37.3-56.4% (wheat) more residue biomass than CT. The N-release from surface-retained residues was 32-38% and 33.1-38.4% lower in maize and wheat, respectively than to incorporated residues. After 365 days, N-release was reduced by 24.4-31% (maize) and 26-30.8% (wheat) under surface retention. Surface residue (SR) retention delayed residue-derived N release in CA-based ICMPs:_5-8 despite higher crop N uptake, creating an early-season (30-90 d) N synchrony gap. Although SR supplied more N later in the season, early N limitation was evident compared with soil incorporation under CT-based ICMPs:_1-4. The CA practices increased NO₃^--N in 0-15 cm soil by 29.4-44.4% (maize) and 26-33% (wheat) at flowering. However, N-use efficiency (NUE) improved by 16-19% (maize) and 6.3-10.2% (wheat), while N uptake rose by 75.7-88.2% and 65-74.5%, respectively. Moreover, the plots maintained for the CA-based ICMPs led to the ∼19.3-20.4% (maize) and ∼14% (wheat) increased grain yields compared to the CT. Thus, the surface retention of residues with a wider carbon-to-nitrogen (C/N) ratio, such as maize and wheat can improve the soil health through slower decomposition rates, thereby positively impacting the soil N-dynamics and sustaining the long-term crop productivity.