LONG-TERM EXPERIMENTAL STUDY ON COMPONENTS AND CHANGES OF PHOSPHORUS IN FLUVO-AQUIC SOIL OF TIANJIN SUBURBS
Yao Bingui;Yao Lizhu;Wang Ping;Zhang Xi and Wang Defeng(Tianjin Soil and Fertilizer Institute, Tianjin 300192)
Effect of long-term fertilizahon on components and changes of phosphorus influvcraquic soil was studied in Tianjin during 1979- 1993. Results showed thatinorganic phosphorus was predominanL in which Ca-P occupied the largest percentage,O-P was second only to Ca-P and only small part was the Al-P and Fe-P. Long-term fertilizahon could significantly influence both the content of soil available P and the range of itS changes. The effects of chemical phosphorus were more obvious than those of organic sources. The increasing and decreasing of soil available P depended heavily on whether chemical phosphorus was applied or not,soil available p increased or decreased at the rate of 1 mg / kg when 45kg P / ha was added or removed. In addition, our study also suggested that the changes of soil available P differed with the periods of experiment at time. Generally speaking, soil available P changed largely in the first two years, and the changes became smaller in the later 6-8 years, finally it remained in a normal value with quite small changes. Soil phosphorus could be balanced in 15 years when l8 kg / ha. year P2O5 was applied for per 100 kg of grain yield under the wheat-corn cropping system with the grain yield of 11400kg / ha in total.
【CateGory Index】： S153