Xu Lian-Fang, Wang Ke-Lin, Zhu Han-Hua, Hou Ya, Zhang Wei
Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
Ying Yong Sheng Tai Xue Bao. 2008 May;19(5):1013-8.
Selecting the main land use types (shrub land, secondary forest land, orchard, pasture land, and upland) at the peak-cluster depression in karst region of Northwest Guangxi as test objects, this paper studied the effects of different land use types on soil nutrients. The results showed that, the contents of soil organic matter (SOM), total N, and available N were 86%-155%, 62% -119%, and 66%-215% higher in shrub land and secondary forest land than in orchard, pasture land, and upland, respectively, i. e., increased with the decrease of land use intensity. The contents of soil total P and K were mainly controlled by their origins, but less affected by land use type. Soil available P content was mainly affected by fertilization, while soil available K content was controlled by vegetation cover and water- and soil loss. Land use type was the dominant factor affecting the contents of soil SOM, total N, and available N, P and K. Extensive cultivation could decrease soil nutrient contents and lead to the degradation of cropland soil, while ecological restoration could improve soil fertility. Therefore, in karst region, the measures as changing extensive cultivation into intensive farming, applying organic fertilizers, balance fertilization, and "Grain for Green Project" for > or = 25 degrees slope should be taken to recover and rebuild the eco-environment, and keep the sustainable utilization of land resources.
选取桂西北喀斯特地区峰丛洼地的主要土地利用类型（灌丛地、次生林地、果园、牧草地和旱地）为试验对象，研究了不同土地利用类型对土壤养分的影响。结果表明，灌丛地和次生林地土壤有机质（SOM）、全氮和碱解氮含量分别比果园、牧草地和旱地高86% - 155%、62% - 119%和66% - 215%，即随着土地利用强度的降低而增加。土壤全磷和全钾含量主要受其来源控制，受土地利用类型影响较小。土壤有效磷含量主要受施肥影响，而土壤速效钾含量受植被覆盖和水土流失控制。土地利用类型是影响土壤SOM、全氮、碱解氮、有效磷和速效钾含量的主导因素。粗放耕作会降低土壤养分含量，导致农田土壤退化，而生态恢复可提高土壤肥力。因此，在喀斯特地区，应采取将粗放耕作转变为集约经营、施用有机肥、平衡施肥以及对坡度≥25度的坡地实施“退耕还林工程”等措施，以恢复和重建生态环境，保持土地资源的可持续利用。
