Transformation of Straw ^14C in Ultisol and Vertisol
摘要
Laboratory incubation was conducted to investigate transformation of straw ^14C in Ultisol and Vertisol under aerobic conditiol for 112 d at 30℃，Dried and ground ^14C-labeled rice and majze straws sere mixed with the soils at the rate of 2.5g kg^-1 ,Decomposition of the straw C and native soil C both revealed two stages,being faster during the intial day,and slower thereafter,About 37.33%-48.80% of the straw C and 4.22%-6.83% of the native soil C decomposed by the end of the incubation.The kinds of the straws only slightly influenced the rates of their decomposition in soils,however,some retardation was found in Ultisol at the intial decomposition stage due to its lowr pH.Positvie priming effects were observed in the soils spplied with straw ,and the rate of priming effect ranged from 7.23% to 13.80%.Net losses of native soil C were found under such incubation conditions ,except Ultisol with rice straw.Soil biomass of and ^14C decreased gradually with incubation time,and seemed to be consistent with the decomposition patterns of straw C and native soil C.The ratio of biomass ^12C to biomass ^14C ranged from 1.35 to 3.37 .soil biomass C occupied 1.17%-2.32% of the total soil organic C,and the proportion of biomass ^14C to the residual ^14C varied from 7.3% to 14.3%.