川中丘陵地区近25年来农田土壤有机碳密度变化--以四川省盐亭县为例

Change of Farmland Soil Organic Carbon Density in Hilly Area of Central Sichuan Basin in the last 25 yesrs——A Case Study of Yanting County,Sichuan Province

根据盐亭县第二次全国土壤普查23个土壤剖面的采样记录,2007年采集了这23个土壤剖面样品,并分析测定其土壤有机碳含量,对比发现,盐亭县近25年来土壤平均有机碳密度上升2.70t/hm2,上升幅度为5.65%,该县农田土壤具有微弱的碳汇效应。近25年来该县土壤有机碳密度变化复杂,不同土壤类型之间的变化差异较大。其中,水稻土、黄壤和紫色土有机碳密度均有不同程度的上升,而冲积土的有机碳密度则明显下降。而就土地利用方式而言,水田土壤的有机碳密度呈明显上升趋势(上升幅度15.38%),而旱地土壤有机碳密度则基本上保持稳定少变。该区今后应主要通过改良耕作措施,推广生态农业技术,增加土壤有机物质归还量;加强生态环境建设,搞好水土保持;灌溉水利工程建设进一步稳定和扩大水田面积等措施,以达到稳定和提高农田土壤有机碳储量的目的。

Taking Yanting County, Sichuan Province as a case, change of farmland soil organic carbon density in Hilly Area of Central Sichuan Basin is estimated and analyzed in last 25 years （1982- 2007）. By referencing the data and sampling location of 23 soil profiles in the second national soil surveys in Yanting County, Sichuan Province conducted in 1980s, we re-sampled these 23 soil profiles in the county in 2007. The contents of soil organic carbon were determined and soil organic carbon densities were calculated and compared in pair with the data measured 25 years ago. The result shows that farmland soil organic carbon density of Yanting County has ascended 2.70 t/hm^2 （ about 5.65 % ） in last 25 years. There is a faint carbon sink effect of farmland soil in the county and an obvious difference change among soil families＇ dynamics. Organic carbon density of paddy rice soil, yellow earth and purple soil has ascended in some way, but that of fluvo-aquic soil has descended. As for different land use, organic carbon density of paddy field soil has obviously ascended （ 15.38% ）, and that of dry land soil is almost stable. In order to stabilize and increase soil organic carbon density taken into account： improving farming methods, popularizi of farmland, the following countermeasures should be ng ecoagriculture technology, increasing organic matter returned to soil; enhancing ecoenvironment construction and doing well water and soil conservation; building irrigation works and stabilizing and expanding area of paddy field.