30 a耕作对高寒草地土壤碳氮与颗粒组成的影响

Effect of Cultivation on Soil Carbon and Nitrogen Contents and Particle Composition in Alpine Grassland

根据青海湖流域1987—2010年5期遥感图像解译,在青海湖北部区域存在毗邻的30 a未曾变动草地和耕地。以这两类土壤为研究对象,对其0~60 cm土层的土壤总碳、土壤全氮、土壤粒度组分进行对比研究。结果表明:草地和耕地土壤总碳和全氮含量以30 cm为界,分异明显,界上草地总碳和全氮含量大于耕地,而界下两者之间差异较小。另外,草地总碳和全氮含量最大值出现在0~10 cm,耕地总碳和全氮含量最大值出现在10~20 cm。草地和耕地粒度组成上都属于砂黏壤级,其中草地粉砂和黏粒大于耕地,而砂含量小于耕地。30 cm以上,草地和耕地间土壤粒度组分差异大,30 cm以下差异小。草地土壤黏粒和粉砂组分与总碳(P<0.05)、全氮(P<0.01)呈显著相关,而土壤砂粒组分与其相关性不显著;耕地总碳和全氮与各土壤粒级组分之间均无显著相关性。

According to the five remote sensing image interpretations in the Qinghai Lake Basin during the period from 1987 to 2010 ,there was the 30-year unchanged farmland and grassland in the zone north of the Qinghai Lake. The soil total carbon and total nitrogen contents and the soil particle size composition in soil layers of 0 -60 cm in depth along the soil profiles in grassland and farmland were researched. The result showed that the differentiation of soil total carbon and total nitrogen contents in grassland and farmland was obvious from soil depth of 30 cm, the soil total carbon and total nitrogen contents in grassland were higher than those in farmland soil above 30 cm in depth, and their difference below 30 cm in depth was low. In addition, the maximum values of soil total carbon and total nitrogen contents occurred in soil layer of 0 - 10 cm deep in land. The soil particle size composition in farmland and grassland but in soil layer of 10 -20 cm deep in farm- grassland was silt loam and clay, the silt content in grass- land was higher than that in farmland, and the sand content in grassland was lower than that in farmland. The difference of soil particle size composition in soil layer above 30 cm deep between grassland and farmland was sig- nificant but not so obvious below 30 cm. The clay and silt contents in grassland had the significant correlations with total carbon content （P 〈0.05 ） and total nitrogen content （P 〈 0.01 ）, but there were no significant correlations between sand content and total carbon and total nitrogen contents. There were no significant correlations between to- tal carbon and total nitrogen contents and soil particle size content in farmland.