红壤丘陵区水田和旱地土壤可溶性有机碳矿化对水分的响应  

Response of mineralization of dissolved organic carbon to soil moisture in paddy and upland soils in hilly red soil region

作　　者：陈香碧[1,2] 王嫒华[1] 胡乐宁[3] 黄媛[1,2] 李杨[1,2] 何寻阳[1,2] 苏以荣[1,2] 

机构地区：[1]中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,长沙410125 [2]中国科学院环江喀斯特农业生态试验站,广西环江547100 [3]广西师范大学环境与资源学院,广西桂林541004

出　　处：《应用生态学报》2014年第3期752-758,共7页Chinese Journal of Applied Ecology

基　　金：中国科学院战略性先导科技专项(XDA05070403);国家自然科学基金项目(41171246;41301273)资助

摘　　要：以亚热带红壤丘陵区典型水田和旱地土壤为研究对象，向土壤中添加Hc标记稻草，培养30d后，提取-9原位土壤中结构相似的Hc可溶性有机碳（DOC）；将HC．DOC加入水田和旱地土壤中，并设置45％、60％、75％、90％和105％田间持水量（WHC）5个水分梯度，在标准状态下（25℃）培养100d，监测^14C—DOC在土壤中的矿化过程．结果表明：培养100d后，两种土壤中28．7％～61．4％的标记DOC被矿化为CO2，且5个水分条件下，水田土壤DOC的矿化率均显著高干旱地，这主要是由于水田土壤DOC的结构组成比旱地土壤更简单．好气条件（56％～75％WHC）有利于两种土壤DOC的分解，淹水条件（105％WHC）则有利于DOC的积累．土壤处于好气条件（45％～90％WHC）时，DOC的生物可分解率及易分解态所占比例均随着含水量的增加而增加．100d内，水田和旱地易分解态DOC分别占其累积矿化量的80．5％～91．1％和66．3％-72．4％，说明DOC的生物可分解率主要由其易分解态组分所占比例决定．Typical paddy and upland soils were collected from a hilly subtropical red-soil region. 14C-labeled dissolved organic carbon （14C-DOC） was extracted from the paddy and upland soils in- corporated with 14C-labeled straw after a 30-day （d） incubation period under simulated field condi- tions. A 100-d incubation experiment （25 ℃ ） with the addition of 14C-DOC to paddy and upland soils was conducted to monitor the dynamics of 14C-DOC mineralization under different soil moisture conditions [45%, 60%, 75%, 90%, and 105% of the field water holding capacity （WHC）]. The results showed that after 100 days, 28.7%-61.4% of the labeled DOC in the two types of soils was mineralized to CO2. The mineralization rates of DOC in the paddy soils were significantly higher than in the upland soils under all soil moisture conditions, owing to the less complex compo- sition of DOC in the paddy soils. The aerobic condition was beneficial for DOC mineralization in both soils, and the anaerobic condition was beneficial for DOC accumulation. The biodegradability and the proportion of the labile fraction of the added DOC increased with the increase of soil mois- ture （45%-90% WHC）. Within 100 days, the labile DOC fraction accounted for 80.5%-91.1% （paddy soil） and 66.3% -72.4% （upland soil） of the cumulative mineralization of DOC, implying that the biodegradation rate of DOC was controlled by the percentage of labile DOC fraction.

关 键 词：可溶性有机碳 矿化 水分 水田 旱地 

分 类 号：S153.6[农业科学—土壤学]