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在宁南山区黄土丘陵区开展了退耕还林还草工程效益监测研究,测定了不同坡位退耕还林还草地的土壤养分。对土壤养分单因子分析结果表明:在同一坡面上,随着坡位的降低,退耕还林还草地0—100 cm土层土壤有机质、全氮、全磷、速效氮、速效磷平均含量增加;从不同坡位退耕还林还草地各层土壤养分含量来看,随着土层深度的增加,土壤有机质、全氮、全磷、速效氮、速效磷、速效钾含量在降低。说明半干旱黄土丘陵区林带间种植的苜蓿经营粗放,加剧了土壤养分的失调。
In the loess hilly region of Ningnan mountainous area, the monitoring and study on the benefits of returning farmland to forest and grassland project was carried out, and the soil nutrients of returning farmland to forest and grassland at different slope positions were measured. The results of single factor analysis on soil nutrients showed that the average contents of soil organic matter, total nitrogen, total phosphorus, available nitrogen and available phosphorus increased with the decreasing of slope position on the same slope in the 0-100 cm soil layer The content of soil organic matter, total nitrogen, total phosphorus, available nitrogen, available phosphorus and available potassium in soil decreased with the increase of soil depth in different soil layers in different slope positions of returning farmland to forest or grassland. The results showed that alfalfa planted extensively in the semi-arid loess hilly region intensified the imbalance of soil nutrients.