开垦草地对土壤有机碳库构成与来源的效应

以广西西北部喀斯特地区的开垦草地生态系为对象,研究了草地开垦变为不同农田后对土壤有机碳库的效应。结果表明,草地开垦为农田后,土壤可溶性有机碳、微生物生物量碳及总有机碳的含量显著下降。自然草地开垦后,柑桔地土壤有机碳含量高于农作用地土壤。玉米与甘蔗轮作土壤有机碳含量高于甘蔗连作。13C示踪结果表明,柑桔地土壤有机碳中来源于草地的含量高于农田土壤;农田土壤有机碳中来源于草地的随种植年限的增加而降低。在玉米与甘蔗轮作的农田中,土壤有机碳中来源于玉米的高于甘蔗连作土壤有机碳中来源于甘蔗的。

IMPACTION OF GRASSLAND RECLAMATION ON THE COMPOSITION AND DERIVATION OF SOIL ORGANIC CARNON POOL

The study on the impact of conversion of permanent grasslan conducted in the reclaimed grassland in Karst area of northwest Guangxi d to farmland on the soil organic carbon pool was The result showed that soil dissolved organic carbon, microbial biomass carbon and total organic carbon declined significantly after the conversion of permanent grassland to farmland. The level of soil organic carbon in the soil growing citrus trees was higher than that in the cropland, and the concentration of soil organic carbon in the cropland with the rotation of corn and sugar cane was higher than that in the cropland with successional sugar cane. The result of ^13C isotope tracing indicated that soil organic carbon derived from original organic carbon of previous grassland in the land growing citrus tee was higher than that in the farmland, soil carbon derived from the original organic carbon of previous grassland declined in cropland with the increase of years of planting crops, and the soil organic carbon derived from corn was higher than that derived from sugar cane in the cropland with the ration of corn and sugar cane.