Assessing C-N balance and soil rejuvenation capacity of vermicompost application in a degraded landscape: A study in an alluvial river basin with Cajanus cajan.

The value and potential of organic-dependent agriculture has gradually become realized worldwide despite scarcity of data on its ability to rejuvenate land quality. In this work, a popular cultivar of Cajanus cajan was grown in a nutrient-fatigued area with vermicompost (VC) and farmyard manure (FYM) to partially replace chemical fertilization (CF) (reduced by 10 and 50%) over a four-year period. C-N mineralization kinetic equations were applied for the first time to assess the efficacy of vermicompost-based nutrient schemes on C-N balance in arable soil. The results suggested that 10 and 50% replacement of chemical fertilization with vermicompost was helpful to significantly improveC- and N-based mineralization in the cultivated soil. In addition, the gains of humified C (humic and fulvic acid) content (such as 4-and 10-fold increases) were achieved under CF₅₀/VC₅₀ and CF₉₀/VC₁₀ treatments, respectively. In the CF₅₀/VC₅₀ treatment, there was apparent improvement in soil organic C storage (SOC_str) (42.6-57.4%), water holding capacity, and microbial health along with reduction in bulk density (6.10-13.0%). Moreover, improvement in soil quality was strongly evident in terms of crop production with the application of CF₅₀/VC₅₀. Overall, this study successfully validated that vermicompost can be used effectively to achieve sustainable agricultural growth by efficiently arresting land degradation.