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Carbon release from brown limestone and red soils in response to addition of Fe(OH)3 and CaCO3.

XIAO Mou-liang1,2, CHEN Xiang-bi1,3, LI Yang1,3, HE Xun-yang1,3, SHEN Yan4, SU Yi-rong1,3**   

  1. (1Key Laboratory of Agroecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China; 2Guangxi Normal University, Guilin 541004, Guangxi, China; 3Huanjiang Observation and Research Station for Karst Ecosystems, Huanjiang 547100, Guangxi, China; 4Bijie Company of Guizhou Tobacco Company, Bijie 551700, Guizhou, China)
  • Online:2014-11-10 Published:2014-11-10

Abstract:

To clarify the effects of minerals on soil organic carbon mineralization in soil evolution, typical brown limestone soil and red soil with both high and low organic carbon contents were collected from a subtropical karst region. An 80-day incubation experiment (25 ℃) by adding either Ca14CO3 or Fe(OH)3 to the test soils was conducted to study the release process of original organic and inorganic carbon. Results showed that the addition of either Ca14CO3 or Fe(OH)3 promoted the carbon release. At the end of the incubation, the accumulatively released amounts of the original carbon (organic and inorganic carbon) were 823.8-1367.2 mg·kg-1 and 502.5-635.7 mg·kg-1 after the additions of Ca14CO3 and Fe(OH)3, respectively. This result indicates that the soil evolution from brown limestone soil to red soil in karst region may increase the stability of carbon stock. After adding Ca14CO3 and  Fe(OH)3, the priming effect on soil carbon was strongly related to the original soil carbon content, and this correlation was in the order of red soil with high organic carbon content > red soil and brown limestone soil with low organic carbon content > brown limestone soil with high organic carbon content (P<0.05). During incubation, the variation in dissolved organic carbon (DOC) content corresponded to the priming effect on the original carbon, implying that the DOC could be an important indicator of the priming effect for both soils. However, the variation in microbial biomass carbon did not correspond to the priming effect on the original carbon, indicating that the priming effect on the original carbon was probably determined by changes in physical and chemical environments after adding Ca14CO3 and Fe(OH)3, and was rarely contributed by soil microorganisms.

 

Key words: tea cultivation, specialization, location, geographically weighted regression, Anxi County