含水量对14C标记秸秆和土壤原有有机碳矿化的影响

 【目的】研究土壤含水量与土壤有机碳矿化的关系。【方法】标准培养条件（25℃，100%空气湿度）下，应用14C示踪技术研究了6个水分梯度下（30%、45%、60%、75%、90%和105%WHC，WHC为最大田间持水量）添加物料和旱地土壤有机碳的矿化特征。【结果】在100 d的培养期内，添加物料和土壤原有有机碳的累积矿化量随含水量的提高而增加，且与含水量呈极显著正线性相关关系。在105%WHC的处理中，添加物料和土壤有机碳的累积矿化量均最大，为146 ?g·g-1和0.76 mg·g-1，是其它处理中添加物料和土壤有机碳矿化量的1.24～1.68和1.33～3.01倍。100 d内，添加物料的矿化率约20%～33%，土壤有机碳的矿化率约1.0%～3.1%。【结论】在30%～105%WHC的范围内，含水量对土壤原有有机碳矿化量的影响更明显，且渍水促进添加物料和旱地土壤有机碳的矿化。

Effects of Soil Moisture Content on the Mineralization of Added 14C-Labbelled Straw and Native Soil Organic Carbon in Upland Soil

【Objective】Soil water plays a crucial role in the accumulation and mineralization of soil organic carbon (SOC). 【Method】 In laboratory, 14C-labelled rice straw was added into upland soil and incubated under 30%, 45%, 60%, 75%, 90% and 105% water holding capacity (WHC) at 25℃, 100% air humidity for 100 days. 【Result】The accumulative mineralized amount of added organic materials (AOM) and native SOC both increased as moisture content increased from 30% to 105% WHC, and their relationships were positively linear correlation (n=6, R2 =0.9174, P<0.001 and n =6, R2 = 0.9649, P<0.001, respectively). During 100 d incubation period, equivalent of 20-33 percent of AOM and 1.0-3.1 percent of native SOC were mineralized. The accumulative mineralized amount of AOM and native SOC were highest under 105% WHC conditions and the amounts were 146 ?g·g-1 and 0.76 mg·g-1, respectively, which were 1.68, 1.35, 1.40, 1.24, 1.16 times and 3.01, 2.04, 1.72, 1.40, 1.33 times to that in soils under 30%, 45%, 60%, 75%, 90% WHC conditions, respectively. 【Conclusion】 This is suggested that in laboratory incubation, the impact of soil moisture content on the mineralization of native SOC was more sensitive to the mineralization of AOM. Results also revealed that the increases in soil moisture content from 30% to 105% WHC will accelerate the mineralization of AOM and upland native SOC.