Response Of Soil Organic Carbon Mineralization In Typical Karst Soils Following The Addition Of 14c-Labeled Rice Straw And Caco3

Abstract

BACKGROUND: Organic substrates and calcium are important factors controlling organic matter turnover in Karst soils. To understand their effects on soil organic carbon (SOC) mineralization, an incubation experiment was conducted involving a control treatment (CK), the addition of a 14C￢ﾀﾐlabeled rice straw (T1), CaCO3 (T2), and both 14C￢ﾀﾐlabeled rice straw and CaCO3 (T3) to two types of Karst soils (terra fusca and rendzina) and a red soil from southwestern China.

RESULTS: Cumulative mineralization of the rice straw over 100 days in rendzina (22.96 mg kg￢ﾈﾒ1) and terra fusca (23.19 mg kg￢ﾈﾒ1) was higher than in the red soil (15.48 mg kg￢ﾈﾒ1; P < 0.05). Cumulative mineralization of native SOC decreased following addition of 14C￢ﾀﾐlabeled rice straw in the rendzina and terra fusca but increased in the red soil (negative and positive priming effects on native SOC). The turnover times of 14C￢ﾀﾐlabeled microbial biomass C (MBC) in the red soil, terra fusca and rendzina were 71 ￂﾱ 2, 243 ￂﾱ 20 and 254 ￂﾱ 45 days, respectively. By adding CaCO3, the accumulation of SOC was greater in the Karst soils than in the red soil.

CONCLUSION: Although the interactions between rice straw decomposition and priming effects on native SOC are not yet understood, there was considerable variation between Karst and red soils. Soil calcium was a positive factor in maintaining SOC stability. MBC from rice straws was stable in terra fusca and rendzina, whereas it was active in the red soil. The Karst soils (terra fusca and rendzina) used in this study benefited SOC accumulation. Copyright ￂﾩ 2011 Society of Chemical Industry