Carbon sequestration potential of coconut based cropping systems under integrated nutrient management practices
Carbon sequestration plays a major role in mitigating climate change by converting atmospheric carbon into long lived wood biomass and soil carbon pool. The present investigation emphasizes sequestration of above ground and soil carbon stock of coconut based cropping systems under integrated nutrient management (INM) practices. The experiment was conducted with three cropping sequences of vegetable crops as intercrops in coconut garden under four different integrated nutrient management practices in FRBD with five replications during 2012 to 2014 at Horticulture Research and Extension Station, Arasikere, Hassan District, Karnataka (India). The incremental increase in the carbon sequestration by palms after two years was to the tune of 3.01 t ha-1 under intercropping system compared to 2.31 t ha-1 recorded under the monocropping system. Baby corn-gherkin sequence recorded significantly the highest soil carbon stock i.e., 19.17 Mg C ha-1 and 20.43 Mg C ha-1 at 0-30 cm depth during 2012-13 and 2013-14, respectively. Among the INM practices, soil carbon stock was significantly the highest in treatment with 5 tonne FYM + 50 per cent N as vermicompost + 50 per cent N as CCP + vermiwash spray + Azotobacter (21.16 Mg C ha-1 and 20.95 Mg C ha-1 at 0-30 cm, during 2012-13 and 2013-14, respectively) and the lowest was in inorganic fertilizer alone (17.94 Mg C ha-1 and 17.96 Mg C ha-1 at 0-30 cm, during 2012-13 and 2013-14, respectively). A significant difference was observed in the soil carbon pool potential due to interaction of the cropping sequence and INM practices and it was the highest under green manure–cucumber sequence coupled with application of 5 t FYM + 50 per cent N as Vermicompost + 50 per cent N as composted coir pith (CCP) + Vermiwash spray + Azotobacter at 0-30 cm depth (21.49 mg C ha-1 and 19.81 mg C ha-1 during 2012-13 and 2013-14, respectively).