渝东南岩溶山地土地利用方式对土壤有机碳时空分布特征的影响

摘要

Organic carbon content is an important index for measurement of land quality. Its change has direct effects on land fertility and growth status of vegetation. The organic carbon spatial-temporal patterns in Xiushan, Qianjiang and Youyang areas is analyzed in four different land use patterns, dry land, paddy field, vegetable garden and orchard, with geostatistical approach through field work, sampling and analysis in the paper. The result suggests that the contents of SOC in the cultivation horizon and subsoil horizon in vegetable garden is the highest, while that in dry land is the lowest, and the differences between them are remarkable. The contents of SOC in the ground layer in orchard are the highest, while that in the paddy land is the lowest, and the differences between them are unremarkable. Different land use patterns has the same effects on SOC of soil section, descending from upper to lower layers, that is contents of SOC in cultivated horizon is the highest, while that in subsoil is the lowest, and decreasing amplitute is largest in paddy field and least in dry land with remarkble differences. Compared with the second soil survey conducted in 1984, the content of SOC in the cultivation horizon (0-20 cm in thickness) has been increasing for 20 years except dry land; the increasing range of SOC in vegetable garden is the biggest and in the paddy field the smallest. But on the whole,thecontent of organic in soil in the study area is relatively low, so approaches of enhancing the ability of carbon storage of the soil should be developed and introduced new farming technology such as no-tillage and straw returning in order to improve the content of organic of the land.%通过野外调查、采样和分析,运用地统计学方法,选择旱地、稻田、菜园和果园四种地利用方式,分析了渝东南秀山、黔江、酉阳三地土壤有机碳(SOC)的时间和空间分布特征.结果表明:空间上,在耕作层和心土层SOC含量都是菜园最大,旱地最小,且差异显著；而底土层果园最大,稻田最小,差异不显著；不同的土地利用方式对土壤剖面SOC含量的影响一致,自上而下依次降低,均为耕作层SOC含量最高,底土层最低,稻田降幅最大,旱地最小,且差异显著；时间上,与1984年第二次土壤普查相比,除旱地外20多年来渝东南岩溶区0～20 cm耕层SOC含量普遍升高,其中菜园的增加幅度最大,稻田最小.但总的来说,研究区岩溶山地土壤有机质含量普遍较低,建议通过人为施肥提高有机质的含量,探索和推广应用免耕、少耕、秸秆还田等耕作措施,增加农田土壤固碳能力.