无锡市郊区土壤普查结果:一万八千亩常年旱生菜地,有机质含量为2。3—3.0%,全氮为0.12—0.18%,速效磷为14.2—33.5ppm,速效钾为79—105ppm,供氮强度10.供磷强度1.6左右,属于中上级肥力水平。但田块间的差异很大,有效磷低于20ppm的,占35%;有效钾低于8 0ppm的,占 12%;pH 5以下的, Wuxi suburb soil survey results: 18000 acres of perennial dry vegetable, organic matter content of 2.3-3.0%, total nitrogen is 0.12-0.18%, available phosphorus is 14.2-33.5ppm, available potassium is 79-105ppm, For nitrogen intensity 10. For phosphorus intensity of about 1.6, belonging to the level of fertility. However, the difference between fields is very large, the effective phosphorus is less than 20ppm, accounting for 35%; the effective potassium is less than 80ppm, accounting for 12%; pH below 5,