Identifying optimum residue levels for stable crop and water productivity and carbon sequestration under a conservation agriculture based rice-wheat system

Abstract

To sustain food-production targets while reducing residue burning in the Indo-Gangetic Plains, adoption of conservation agriculture (CA) is desirable, amongst other potential adaptations. To identify the optimum residue levels for sustainable CA, the Agricultural Production Systems Simulator (APSIM) model was used to analyse 37 years (1984–2022) of diverse CA scenarios on productivity, sustainability and carbon footprints in the rice-wheat cropping system (RWCS). The study highlighted that APSIM has the capacity to capture the crop performance, phenology and CA scenario in RWCS. The scenario analysis indicated that maximum system productivity (SP) was recorded under higher residue (HR-9.33 t ha−1) followed by higher-medium residue (HMR-8.97 t ha−1) scenarios of CA, as compared to conventional tillage (CT-8.75 t ha−1). Stable productivity was achieved under CA. Sustainable yield index and sustainable value index were significantly higher under HR (0.83 and 0.79, respectively) followed by HMR. The soil organic carbon concentration is predicted to increase ∼30–95% in CA with a carbon sequestration rate of 0.1–0.37 t ha−1 yr−1. The system water productivity was highest under HR (3.68 kg ha−1 mm−1) which was ∼10% higher than CT. Overall, the study revealed that the APSIM model is efficient in capturing CA effects in South Asian RWCS and that the adoption of CA results in greater and stable yields, higher water productivity, and more carbon capture over the long term, while reducing production costs.