农牧交错带退耕还草对土壤化学性质的影响

Effects of Returning Cultivated land to Grassland on Soil Chemical Properties in the Agro-pastoral Transitional Zone of Northern China

在北方农牧交错带，以马铃薯（Solahum tuberosum L．）地为对照，研究了退耕地建植多年生人工草地对土壤化学性质的影响。结果表明，退耕地种草可提高土壤的有机碳含量，增加表层土壤的全氮含量。人工草地0～10cm土层有机碳和氮素含量分别较耕地高20．84％和18．21％；退耕地种草对土壤速效磷含量、电导率和pH水平无显著影响；耕地与人工草地土壤化学指标之间的差异在很大程度上受生长季节的影响，选择适宜的采样季节是评价退耕地种草效果的关键。

The ecosystem structures and functions in agro-pastoral transitional zone of northern China have been severely destroyed by long-term rangeland reclamation. It is believed that planting perennial grasses in cultivated land has the potential to improve the soil fertility and the ecosystem service functions. The effect of returning cultivated land to perennial grassland on soil chemical properties was studied in agropastoral transitional zone of northern China in comparison with potato plantation. The results showed that contents of soil organic carbon and total nitrogen increased by 20. 84% and 18.21% in 0～10 cm soil layer after returning potato lands to grasslands. Artificial grassland had no significant influence on soil available phosphorus content, electric conductivity and pH levels. The differences of chemical property indexes between cultivated land and grasslands depended upon growing seasons which points out that suitable sampiing season might be more important in evaluation of the efficiency of artificial grasslands.