Changes in soil organic matter and total nitrogen in the 0-20 cm soil layer of paddy fields under different fertilization treatments were monitored and studied at 5 long-term field experiment sites (1986-2003).Results indicated that the treatments of chemical fertilizer plus medium-or high-rate of organic manure showed much better effect in increasing soil organic matter and total nitrogen in the soil than the treatments of chemical fertilizer or incorporation of straws into the soil did,and the effect rose with the rate of organic manure applied,suggesting the combined application of manure and chemical fertilizer is the most effective measure to increase soil organic matter and total nitrogen.Soil organic matter content in paddy soils different in fertilization pattern tends to increase or decrease and fluctuates from year to year.