Increasing Soil Organic Carbon Through Crop Diversification in Cereal–Cereal Rotations of Indo-Gangetic Plain

Continuous practices of cereal–cereal rotations in Indo-Gangetic plain (IGP) region have emerged with several soil related issues including depletion of soil organic carbon (SOC). Crop diversification remains a conceivable option to address this issue. Here, the authors envisaged the long-term alternate-year inclusion of chickpea in upland maize–wheat and lowland rice–wheat systems on SOC, C-dynamics and C management indices under organic, inorganic, and control nutrient management. Inclusion of chickpea in rice–wheat and maize–wheat systems increased total organic C (TOC) by 6.5 and 13.4%, and particulate organic C (POC) by 94.7 and 41.3% in the surface soil (0–0.2 m), respectively. In both the production systems, enrichment of very-labile C (Cfrac 1 ) and labile C (Cfrac 2 ) fractions were apparent with inclusion of chickpea. Very-labile (Cfrac 1 ) (36.6–37.9%) in upland and less-labile (Cfrac 3 ) (29.1–31.7%) in lowland were the dominant C-fractions. Subsequently, upland conditions had higher active C-pool; conversely, lowland ecosystem enriched passive C-pool, which is desirable for long-term persistence of soil C. The higher values of TOC, POC, and C-fractions were registered in organic nutrient treatment over inorganic and control treatment. In lowland, chickpea residue C had a low rate of stabilization as compared to cereal residue. In lowland, crop diversification with chickpea increased lability-index and C-management index; however, the effect was marginal in upland. Thus, inclusion of chickpea in the cereal–cereal rotations of IGP would be a potential long-term strategy to improve SOC and to ensure production sustainability. © 2017, The National Academy of Sciences, India.