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三峡库区长期以来人地矛盾突出,蓄水和移民搬迁使土地资源进一步减少,过度开发引起的土壤肥力下降和生态退化问题日趋严重。通过布点调查和土壤取样,对秭归县水田坝乡区域不同海拔高度和农业土地利用管理方式土壤养分状况及其变化趋势进行分析。结果表明:研究区域内山地农业已普遍采用梯田进行保护性耕作,海拔600～700m区域主要开辟为脐橙园,700～900m区域山地主要种植常规作物;研究区域土壤有明显粗骨化和沙质化特性,其肥力特征是蓄水力偏弱,持水保肥性较差,但通气和透水性好,易耕作;研究区域土壤有机质含量偏低,中高海拔区域土壤有机质、全氮含量相对较高,而低海拔区域土壤全磷、全钾含量较高;坡改梯有利于改善土壤肥力状况,提高土壤氮磷养分含量;根据2005～2010年研究结果,研究区域土壤肥力退化趋势仍未得到控制,同时因水土流失和化肥大量使用,该区域大多数土壤有机质含量、全氮、全磷和全钾含量呈降低趋势,而土壤速效养分含量有增高趋势。
The Three Gorges reservoir area has been characterized by long-standing contradictions between man and land. The relocation of water storage and immigrants has further reduced the resources of the land. The problems of declining soil fertility and ecological degradation caused by over-exploitation have become increasingly serious. Based on the distribution survey and soil sampling, the status and trend of soil nutrients under different altitude and agricultural land use management in the paddy fields of Zuigui County were analyzed. The results showed that: the mountainous areas in the study area have been using conservation terraces for conservation tillage. The areas between 600 and 700 meters above sea level are mainly open for navel orange groves. The 700 to 900 meters area is for planting conventional crops. The study area shows obvious coarse ossification and sandy soil characteristics , And its fertility is characterized by weak water storage capacity, poor water and fertility conservation, good aeration and water permeability, and low soil organic matter content. Soil organic matter content is relatively low in the study area, and soil organic matter and total nitrogen content are relatively high in the middle- While the content of total phosphorus and total potassium in the soil in the low altitude region is higher. The slope to the ladder is conducive to improving soil fertility and increasing the content of nitrogen and phosphorus in the soil. According to the research results from 2005 to 2010, the degradation trend of soil fertility in the study area has not yet been controlled, At the same time, due to soil erosion and heavy use of chemical fertilizers, most of the soil organic matter, total nitrogen, total phosphorus and total potassium in the region showed a decreasing trend while the available nutrient content in the soil increased.