Abstract: In April 2005, a total of 41 soil samples were collected from the sandy loam soil (Usto-chrepts) under orchard, vegetable, corn (Zea maize L.) and soybean (Glycine max L.) in Yan-huai basin of Beijing, and their physical, chemical,and biological properties were analyzed. The results showed that the contents of soil organic carbon (SOC), total nitrogen (TN) and total phos-phorus (TP) in vegetable field, orchard field, and high-input corn field were obviously higher than those in soybean field and mid- and low-input corn fields. In these fields, SOC content varied from 7.67 to 10.00 g·kg^-1, TN content varied from 0.75 to 1.12 g·kg^-1, and TP content varied from 0.63 to 1.00 g·kg^-1. Soil available phosphorus (AP) content and electric conductance (EC) were significantly higher in vegetable field than in other fields, while no significant differences in soil physical properties were observed among the four land use types. The soil quality index of orchard and vegetable fields was 0.525 and 0.503, respectively, being higher than those of corn and soybean fields (0.417—0.494). Vegetable field had the highest efficiency of soil nutrients, but non-point source pollution risk should be minded. For soybean field and mid- and low- input corn fields, intensive management should be practiced to improve their soil quality.

Key words: Monocrotophos, Sciaenops ocellatus, Na⁺/K⁺-ATPase, Microstructure, Ultrastructure