Study On Changes Of Soil Organic Matter And Total Nitrogen In Paddy Soil Under Long-Term Experiments

Field investigation and soil sample analysis methods were adopted on the six long—term experiments in Hubei Wuhan Station, Chongqing Beibei Station, Hunan Wangcheng Station, Hunan Qiyang Station, Jiangxi Nanchang Station, Zhejiang Hangzhou Station, China.Consider factors of increasing soil organic matter and total Nitrogen and fertilization of each experiment treatment; This paper studies on the changing of soil organic matter and total Nitrogen in paddy soil . Results showed as follows:CK treatment of SOM(total Nitrogen) has the varying degree down trend except wangcheng and hangzhou, beibei is the greatest reduction, which has the average annual decline 0.23g/kg;N and NP treatment also have certain declining which is higher than CK treatment;Balance fertilizer treatment NPK has the higher rising trend than N,NP,CK treatment; There is a scale relationship between the rate of SOM(total Nitrogen) and the organic fertilizer, among the first 10 years the SOM of 30F+70M,50F+50M and 70F+30M promoted 12.8g/kg,5.0g/kg and 5.0g/kg separately.With the extention of test time, the annual increment of SOM all declining, M and M+S treaments were dropper than chemical fertilizer significantly; The response value of qiyang and Hangzhou′s M and combination treatment were significantly higher different than any other areas, the size order was qiyang> wuhan >beibei>hangzhou。there was a positive correlation between SOM content and accumulated production in Qiyang, this positive correlation under M treatment was more significantly than that combination.With the extention of test time, the annual increment of TN all declining, not the line trend, NPK,NPKM and M treatments in qiyang and Hangzhou, the proportional fertilizer and NPK treatments in Nanchang, NPK treatment in wuhan all declining during the first years, then this declining become slowly; because initial value of TN in Chongqing, wangcheng and wuhan was relatively lower, all showed that rising to maximum first, then gradually decreases to stable station. Hangzhou with organic-inorganic fertilizer was in under the condition of soil crop accumulated production and total nitrogen content of chemical fertilizer and organic fertilizer risk than under the conditions were obvious, and its change trend for 0.2504 r value, the higher the cumulative yield, soil total nitrogen content were lower. There was a similar relationship between the annual increment of total Nitrogen and the responsibility to organic fertilizer, Under the condition of chemical fertilizer, there was a positive correlation between the total nitrogen content and accumulated production in Beibei and Wuhan except Hangzhou and Qiyang, the correlate equation was y=0.004x+1.323(r=0.7338)and y=0.005x+1.7963(r=0.7203*)respectively; The trends of the responsibility total Nitrogen promotement to accumulated production was similar both under organic and chemical fertilizer conditions, the correlate equation was y=0.0057x+1.3791(r=0.6444)and y=0.0101x+1.8453(r=0.8954**)respectively; The correlation between crop accumulated production and total nitrogen content was more significantly in combination treatment than that M and chemical fertilizer treatments, the higher of Cumulative yield, the lower about the TN content.The relationship between TN content and accumulated yield and cumulative fertilizer was similar, there was a positive correlation between TN content and accumulated fertilizer in beibei and wuhan except hangzhou, the size of correlation coefficion order was wuhan>beibei >hangzhou>qiyang. There was aiso a positive correlation between TN content and accumulated yield in beibei and wuhan sites, the correlate equation was y=0.0981x+1.3845(r=0.7008)and y=0.1111x+1.91(r=0.8804**)respectively; there was a similar relationship between TN content and accumulated yield with chemical fertilizer, the correlate equation was y=-0.2463x+2.9993(r=0.7758*).