科尔沁沙地不同土地利用和管理方式对土壤质量性状的影响

研究了科尔沁沙地退化草地开垦后，在14年不同的土地利用和管理方式下土壤物理、化学和生物学性状的特征。结果表明，农林(林草)复合利用模式在土壤粒级组成、孔隙分布、持水性能、有机质和N、P养分、酶活性等方面表现出较好的质量性状特征。有机无机配施、精细管理的灌溉农田次之，而粗放管理的旱作农田。土壤质量性状严重恶化，逐步向流沙方向演变，与科尔沁原生景观草地土壤相比，管理良好的利用系统，土壤物理性状、P含量和一些酶活性指标提高，但有机质和全氮含量明显低，表明已退化生态系统C、N库的恢复和重建需要较长的时间。研究结果表明，不同的土地利用方式和管理措施显著影响土壤质量变化的程度和方向；调整土地利用结构，基本农田实行精细管理，旱作农田退耕还草还林是保护土地资源。实现区域生态恢复和重建的根本选择。

Effects of land use and management on soil quality of Heerqin sandy land

The changes of soil physical, chemical and biological properties under different land use and management lasted for 14 years were investigated on the Heerqin sandy land. The results showed that among various land use systems marked differences exhibited in soil quality indicators, including soil particle composition, porosity distribution, bulk density, water-holding capacity, organic matter and nutrient contents, pH, and enzyme activities. Most of these soil quality indicators were the highest in the orchard intercropped with crops and perennial grass (agroforestry systems), intermediate in the well-management irrigated farmland, and the lowest in the less-management dry farmland. Compared to the primary grassland soil, although some soil properties, including porosity distribution, water-holding capacity, phosphorus content, and enzyme activities, were improved in the well-management systems, soil organic matter and nitrogen contents were significantly lower. It suggested that a long-term input of organic matter was needed for the restoration and reestablishment of soil carbon and nitrogen pools in the seriously degraded ecosystem. Inappropriate land use and management could rapidly worsen soil quality, and hence, from a perspective of soil resource conservation, a preferable way for preventing soil degradation and achieving sustainable land use should be to give up the cultivation of degraded dry farmlands, and to adopt more effective and appropriate soil management and cultivation practices.