Soil carbon pools under rubber (Hevea brasiliensis) based agroforestry systems in South India.

To enhance carbon sequestration in soil and mitigate climate change, a better understanding of the effects of land management practices on soil carbon (C) pools is essential. The impacts of land preparation methods on soil C accruals and C alterations under two predominant rubber (Hevea brasiliensis) based agroforestry systems viz. rubber–pineapple and rubber–banana in the Western Ghats region of Kerala, India, were highlighted in this study. Soil samples were collected from each agroforestry system at two depths (0–30 and 30–60 cm) after the complete harvest of the intercrops and analysed for total carbon (TC), organic carbon (OC), inorganic carbon, oxidizable OC fractions (F1, F2, F3 and F4) and C in water stable aggregates. Tilling of rubber inter-rows for pineapple planting with earth movers reduced 18% of TC and OC and 23% of SOC stock in the upper 30 cm soil layer. Even though the high amount of soil C was lost during tillage, the high and diverse organic matter turnover in the rubber–pineapple system reduced the negative impact of tillage on soil quality. With respect to the rubber–banana system around 13% increase in TC and OC and 11% increase in SOC stock was observed compared to monoculture rubber. The high litter turnover contributed to greater soil C, indicating high C sequestration potential of both agroforestry systems. The study also advocates the importance and need of reorientation of land management strategies for rubber agroforestry systems to attain global food security and C sustainability from a climate change perspective. [ABSTRACT FROM AUTHOR]