[Effects of soil texture and water content on the mineralization of soil organic carbon in paddy soils].
To understand how soil texture and water content affect the mineralization of organic C in paddy soil, 3 selected soils (sandy loam, clay loam, and silty clay) were incubated (25 degrees C) with 14 C-labelled rice straw (1.0 g x kg(-1)) at water content varied from 45% to 105% of water holding capacity (WHC). Data indicated that, in the sandy loam and clay loam, the mineralization rate of 14 C-labelled rice straw reached the maximum at 75% WHC, as 53% and 58% of the straw C mineralized in the incubation period of 160 d, whereas in the silty clay, it increased gradually (from 41.8% to 49.0%) as water content increased up to 105% WHC. For all of the three soils, the mineralization rate of soil native organic C reached the maximum at 75% WHC, with 5.8% of the organic C mineralized in the same period for the sandy loam, and 8.0% and 4.8% for the clay loam and silty clay, respectively. As water content increased further, the mineralization rate of native organic C in the three soils significantly declined. The mineralization rate of added rice straw and native organic C in all the three soils, was well fitted with a conic curve. These results suggest that water-logging can decrease the mineralization of organic C in paddy soils.
Key Laboratory of Subtropical Agriculture Ecology, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China. yizhu-2004@163.com
Zhong-lin
ZL
Sun
Jin-shui
JS
Wu
Ti-da
TD
Ge
Guo-yong
GY
Tang
Cheng-li
CL
Tong
D002244:Carbon / Q000737:chemistry*; D002250:Carbon Radioisotopes; D009930:Organic Chemicals / Q000737:chemistry*; D012275:Oryza / Q000254:growth & development*; D012987:Soil / Q000032:analysis*; D014867:Water / Q000032:analysis*
D002250:Carbon Radioisotopes; D009930:Organic Chemicals; D012987:Soil; D014867:Water; D002244:Carbon