Abstract
The data from long-term management and cropping systems experiments are needed to assess changes in soil quality, organic carbon pool, and agronomic sustainability. Thus, a 13-year-old soil fertility management experiment was used to assess the impact of crop residues carbon (C) inputs on SOC stock in a rainfed groundnut (Arachis hypogeae L.)–fingermillet (Eleusine coracana (L.) Gaertn) rotation in semiarid alfisol. The application of farmyard manure (FYM) alone or in a combination with chemical fertilizers contributed to higher amounts of C inputs and subsequently to build up a higher SOC pool. Application of 10 Mg ha−1 of FYM and a recommended dose of chemical fertilizer (25:21.8:20.7 and 50:21.8:20.7 kg N, P, K ha−1 for groundnut and fingermillet, respectively) increased soil SOC pool by 41.2% to 73.0 Mg ha−1 with an increase of 9.3 Mg ha−1 over 13 years. Both SOC pool and rates of its sequestration were positively correlated with cumulative C input and sustainable yield index. A minimal input of 1.62 Mg C ha−1 yr−1 is needed to maintain SOC pool at the antecedent level. Balanced application of NPK fertilizers is needed to reduce and reverse the depletion of SOC pool.
Acknowledgements
The authors are grateful to the Indian Council of Agricultural Research (ICAR), New Delhi for funding the project.