Abstract
ABSTRACT Soil organic carbon (SOC) serves a vital role in sustaining environmental quality and supporting agroecosystems. The study evaluated the effects of long-term manuring and fertilization on SOC pools in rice-rice cropping system in the lateritic soils of Central Plain, Kerala, India. Soil samples from the long term fertilizer plots were used to determine the SOC pools. Treatments were: 50% recommended dose of nitrogen (N), phosphorus (P), potassium (K) (50% NPK), 100% NPK, 150% NPK, 100% NPK + lime, 100% NP, 100% N, 100% NPK + farm yard manure (FYM) (100% NPK + FYM), 50% NPK + FYM, 100% NPK + Sesbania aculeata (SA), 50% NPK + SA and no fertilizers or manures (control). Integrated nutrient management (INM) treatments improved the Walkley and Black carbon (WBC) content. Water-soluble carbon (WSC) ranged from 0.009 to 0.012%, with the highest value found in INM. KMnO4-oxidizable carbon ranged from 0.092 to 0.158%. The management practices were found to greatly influence microbial biomass carbon (MBC) in the soil with values 195.55 to 298.19 µg g−1 soils. The treatments had a significant effect on fractions of SOC that are strongly connected to aggregate stability namely, total polysaccharides, and glomalin. Application of NPK from 50% to 150% improved WBC, WSC and MBC by 7.69%, 22.22% and 27.90%, respectively. The INM practices also improved the SOC stocks. The carbon management index (CMI) found to be superior in one receiving INM practices than one receiving prescribed levels of nutrition using only mineral fertilizers.
Published Version
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