耕作方式对绿洲灌区农田土壤有机碳及其分布的影响

依托自2005年开始的田间定位试验,分析了传统平作(CT)、垄作沟灌(FRB)、固定道垄作(PRB)和固定道平作(ZT)4种耕作方式下绿洲灌区农田0～90 cm土层中土壤总有机碳(TOC)、颗粒态有机碳(POC)含量和微生物生物量碳(SMBC)及其分布特征.结果表明: 4种耕作方式下土壤TOC、POC和SMBC在土壤剖面中的垂直分布特征相似,有机碳含量随着土层深度的增加而递减,且处理之间差异逐渐减小.PRB可显著提高TOC、POC含量和SMBC,不同耕作方式下各土层有机碳含量表现为PRB>ZT>FRB>CT.与CT相比,0～10 cm土层中PRB、ZT和FRB处理TOC含量分别增加11.1%～24.8%、9.1%～18.7%和7.8%～8.2%,POC含量分别增加24.1%～26.5%、17.3%～18.7%和-8.2%～10.8%,SMBC分别增加20.5%～28.3%、10.4%～15.2%和3.5%～3.7%.TOC对POC具有明显促进作用.PRB能显著增加土壤POC分配比例,增加有机碳积累.

Degradation characteristics of lignin and cellulose of foliar litter at different rainy stages in subtropical evergreen broadleaved forest

A long term trial was established in 2005 in the oasis irrigation area to determine the impact on the accumulation and distribution of total organic carbon (TOC), particulate organic carbon (POC) and soil microbial biomass carbon (SMBC) in 0-90 cm soil layer of 4 types of tillage including conventional tillage (CT), fresh raised bed (FRB), permanent raised bed (PRB) and zero tillage with control traffic on flat field (ZT). The results revealed that the distribution characteristics of TOC, POC and SMBC in the soil profile were similar in the four tillage treatments, and the carbon content decreased with depth, meanwhile the difference among treatments gradually decreased. PRB significantly increased the TOC, POC contents and SMBC, which presented in the order of PRB>ZT>FRB>CT in the 0-90 cm soil layer. In 0-10 cm soil layer, the TOC was increased by 11.1%-24.8% for PRB, 9.1%-18.7% for ZT and 7.8%-8.2% for FRB when compared with CT; POC was increased by 24.1%-26.5% for PRB, 17.3%-18.7% for ZT, and -8.2% to 10.8% for FRB; SMBC was increased by 20.5%-28.3% for PRB, 10.4%-15.2% for ZT and 3.5%-3.7% for FRB. TOC had a significant promotion effect on POC. PRB significantly increased the proportion of soil POC and enhanced the overall accumulation of organic carbon.