Carbon stock dynamics in soil as influenced by perennial grass-legume mixtures in southern dry zone of Karnataka

A field experiment was conducted at Zonal Agricultural Research Station, Vishweshwaraiah Canal Farm, Mandya, University of Agricultural Sciences, Bangalore from July 2020 to June 2022 to study the carbon stock dynamics in soil as influenced by different perennial grass-legume mixtures in southern dry zone of Karnataka. The experiment was laid out in a randomized complete block design comprising of twelve treatments and replicated thrice. The data revealed that among different grass-legume mixtures, paired row system of B×N hybrid + Desmanthus (2:5) recorded considerably higher credit of soil organic carbon (0.018%) and carbon sequestration in soil (1.12 Mg ha-1) followed by paired row system of Guinea grass + Desmanthus (2:3) (0.016% and 0.99 Mg ha-1, respectively) at the end of the second year. Further, significantly higher green fodder, dry matter and crude protein yield (1802.7, 355.7 and 41.5 q ha-1 year-1, respectively), gross and net returns (Rs. 3,44,072 and 2,58,752 ha-1 year-1, respectively) as well as benefit cost ratio (4.05) were observed with paired row system of B×N hybrid + Desmanthus (2:5) cropping system on a pooled basis which was on par with paired row system of Guinea grass + Desmanthus (2:3) with respect to crude protein yield (38.3 q ha-1 year-1) and B:C ratio (3.67) as compared to other grass-legume mixtures. Considering these results, B×N hybrid paired row + Desmanthus (2:5) followed by Guinea grass paired row + Desmanthus (2:3) were found as the most promising fodder cropping systems for meeting both farmer needs and soil sustainability.