Effects of ryegrass ( Lolium multiflorum ) winter cropping on soil chemical and physical characters were investigated with a field experiment. The results showed the soil bult density decreased by 9 4% under ryegrass winter cropped (RWC) condition

but only 4 0% decrease was observed under winter fallowed (WL) one. Soil organic matter increased by 66% under RWC

but decreased by 14% under WL. Total nitrogen

phosphorus

potassium

and available nitrogen

phosphorus and potassium in soil increased by 26%

32%

14%

and 67%

33% and 78%

respectively under RWC

but under WC

total nitroget

total phosphorus

available nitrogen and phosphorus decreased by 13%

4%

20% and 13%;both total potassium and available potassium increased by 10%. Although the increments of the soil nutrients would be attributed to the input from fertilization

the availabilities of nitrogen and potassium seemed to be affected by the rhizosphere activities

due to the fact that the increments of the two nutrients in the available fragment were larger than that in the total one under RWC

The unusual nitrogen increment

which accompanied with a great net output (28 0 g/m 2) of soil nitrogen by harvesting ryegrass

indicated that there was an unknown income of soil nitrogen.