保护地土壤养分特点

Nutrient Properties in Protected Soils

保护地蔬菜土壤养分状况与大田露地土壤有很大差别．土壤有机质含量高于露地，一般在１５～４０ｇ／ｋｇ，土壤有酸化的趋势．土壤中有效氮的含量明显高于露地土壤，硝态氮的平均含量超过１９０ｍｇ／ｋｇ．土壤有效磷的含量１５８．８ｍｇ／ｋｇ，比露地土壤高出６倍多．土壤有效钾的平均含量２７４．５２ｍｇ／ｋｇ，比露地土壤高出２．５６倍．土壤中交换性钙和镁的含量在临界指标以上，但某些情况下作物出现缺钙和缺镁症．化肥施用量大，决定了保护地蔬菜土壤养分的特点．

The nutrient properties in Protected soils were very different from those of openning soils. The intensive use of fertilizers in greenhouse soils resulted increase in soil organic matter and accumulation of available nutrients. In general, the contents of available N, P and K in protected soils were 2. 5 to 6 times higher than those in openning ones. In addition, the mulched soils tented to be acidified gradually. The contents of exchangeable Ca and Mg were above the critical values but Ca and Mg deficits could be observed sometimes.