Carbon sequestration and soil quality under organic system of local rice (Oryza sativa L.) variety in Tabanan, Bali Indonesia

Abstract Soil organic carbon (SOC) storage has been widely considered as a measure for mitigating global climate change through C sequestration (SOCS) in soils. A study was conducted by evaluating SOC, total N, available P, K, bulk density, and total soil microbes under organic system and conventional of Local rice variety at the same time in two farmer fields (subak Jatiluwih and Wangaya Betan at Mangesta village in Penebel district,Tabanan regency, Bali Indonesia. Half of farmers in those two locations have been managing certified organic system with Red local rice variety for two years (2010-2012), while the other half maintaining conventional system. Composite soil samples were taken at three points at depth of 0-20 cm and 20-40 cm in three replications at each location. Results showed that after two years, organic system resulted in better soil quality and higher SOCS only in Jatiluwih. Significantly higher SOC (3.338%), total N (0.252%), available P (15.84 ppm), K (133.63 ppm), bulk density (0.510 Mg m-3) and higher SOCS (81.354 Mg ha-1) were recorded under organic compared to conventional system. In Wangaya Betan, those components, except bulk density, were not different under two systems. The yield of Red local rice variety under organic was 6.44.t ha-1 compared to 5.12 t ha-1 under conventional system.