关键词: 改良冷冻法, 改良冷冻法

Abstract: In order to identify the variation characteristics of soil organic carbon and total nitrogen in paddy field and its impact on the environment under different fertilization patterns, an investigation was carried out to study the changes in soil organic carbon (SOC) and total nitrogen (TN) as affected by long-term fertilizations of zero fertilizer, NPK fertilizer alone and NPK with straw incorporation in rice-wheat cropping system in paddy soil in Taihu Region. The results showed that the SOC and TN over the soil profile were characterized by a gradual decrease from the top to bottom, and the effect of straw-returning was mainly in the top 0-10 cm soil layer. Both the contents of SOC and TN increased in treatment of NPK fertilizer alone and NPK with straw incorporation, and decreased significantly in zero fertilizer treatment. The increasing of SOC and TN wasn’t significant in NPK fertilizer treatment, but SOC and TN increased significantly in treatment of NPK with straw, being 35.8% and 17.3% respectively during four years. SOC and TN had the same variation trend, which was a significant positive correlation (R2=0.78, P<0.01). The C/N ratio of soils was around 10.0 in Taihu Region, which declined in the past 20 years. Treatment of NPK with straw incorporation could increase the C/N ratio of soil and promote the soil carbon-nitrogen cycling. These results indicated that pattern of NPK with straw incorporation could improve the soil physical chemistry property to enhance the farmland productivity and be worth extrapolating.