Organic based integrated nutrient management scheme enhances soil carbon storage in rainfed rice (Oryza sativa) cultivation

Soil organic carbon (C) management in agricultural fields can act improve soil health and productivity. However, reports on the C release pattern and the interactive effects of plant physiological parameters on soil C storage from subtropical regions of the world where rice is cultivated as a dominant food crop are inadequate. The interactions between plant metabolism, soil C storage, and organic-based nutrient management schemes have been little studied. Hence, a study was undertaken in rainfed winter rice to evaluate the effects of different levels of organics (crop residue (CR) and farmyard manure (FYM)) along with inorganic (NPK) inputs in an alluvial soil. The experiment was conducted in a typical humid subtropical climate in north-eastern India. The CR of the preceding rice crop (pre-monsoon) and cow dung based FYM were used as organic inputs for monsoon rice, which were applied in various combinations with inorganic fertilisers. We studied the influence of these selected nutrient management schemes on soil health attributes, C storage, and plant parameters. The highest gain in C storage (11.65%) was in soil under 80% NPK + CR (5 t ha(-1)) + FYM (10 t ha(-1)) treatment. Correspondingly, significant improvement (P < 0.05) in total C, dissolved organic C, and nitrogen availability in soil was evident under this treatment leading to augmentation of soil organic matter status and the net amount of sequestered C in soil after two years of rice cultivation. Such improvements resulted in greater flag leaf photosynthesis, biomass accumulation, and grain yield than the conventionally managed crops. Overall, this research showcases that organic-dominated nutrient management not only restored soil health but was also able to compensate 20% of the recommended NPK fertilisation without penalty on crop yield.