Study On The Form Characteristics Of Nitrogen In Cultivated Land Soil And Its Influence Factors

In this study,the contents of STN,SAN,Ammo acid nitrogen,Ammonia nitrogen and Ammonia sugar nitrogen in the paddy soil subclass topsoil of Submergic paddy soil, Gleyed paddy soil and Percogenic paddy soil,as well as in gravelic purple soil,gravelic purple big soil and soil were studied in hill region of central Sichuan basin,and the effect of soil parent materials,OM,pH and soil particle composition on them were also studied through field investigation,t-testing,regression and correlation analysis.The main results were as follows:In hill region of central Sichuan basin,the contents of STN,SAN,Ammo acid nitrogen, Ammonia nitrogen and Ammonia sugar nitrogen in topsoil of dry land were 0.51±0.29g kg^-1,24.4±7.29mg kg^-1,19.92±8.23mg kg^-1,77.38±19.48mg kg^-1,12.52±6.78 mg kg^-1.The contents of STN,SAN,Amino acid nitrogen and Ammonia sugar nitrogen in the three soil types from high to low were in the order of soil＞gravelic purple soil＞gravelic purple big soil.As to the content of Ammonia-N,the order was soil＞gravelic purple big soil＞gravelic purple soil,and the difference was significant(P＜0.05).The contents of STN,SAN, Ammo acid nitrogen,Ammonia nitrogen and Ammonia sugar nitrogen in topsoil of paddy field were 0.51±0.44g kg^-1,23.22±14.83mg kg^-1,19.9±12.95mg kg^-1,77.38±20.95mg kg^-1,12.53±9.15 mg kg^-1.The contents of STN,SAN and Ammonia nitrogen in the three subclass soil types from high to low were in the order of Percogenic paddy soil＞Gleyed paddy soil＞Submergic paddy soil.As to the content of Ammo acid nitrogen the order was Gleyed paddy soil＞Percogenic paddy soil＞Submergic paddy soil,and the order of the content of Ammonia sugar nitrogen was Percogenic paddy soil＞Submergic paddy soil＞Gleyed paddy soil,the difference was significant(P＜0.05).In hill region of central Sichuan basin,the content of STN in topsoil of mature soil in J1-2z and J3s were 0.92±0.38g kg^-1 and 0.64±0.47 g kg^-1,and according to the t-testing,the difference was not significant.The content of SAN in these two groups were 34.115±16.87mg kg^-1 34.68±9.39mg kg^-1,and the content of Ammo acid nitrogen in topsoil of mature soil in two parent materials were 38.43±13.98mg kg^-1 and 36.95±12.98mg kg^-1,the difference were not significant.The vertical distribution trends of STN,SAN,Amino acid nitrogen,Ammonia nitrogen and Ammonia sugar nitrogen in soil from different parent materials were consistent.They all decreased from topsoil to lower layers.From 0 to 10 cm,the contents of them were highest.The content of soil clay particles and the contents of STN,Ammo acid nitrogen and Ammonia sugar nitrogen in topsoil were all highly of significant linear relationships,and the correlation coefficients were 0.510^**(n=36),0.490^**(n=36) and 0.429^**(n=36).But there were no significant linear relationships between soil clay particles and the contents of SAN and Ammonia nitrogen,their correlation coefficients were 0.249(n=36) and 0.316(n=36).The contents of soil silt particles and Ammo acid nitrogen were highly of significant linear relationships,the correlation coefficient was 0.459^**(n=36).The content of soil silt particles and the contents of STN and Ammonia sugar nitrogen were both of significant linear relationships,the correlation coefficient were 0.551^* and 0.397^*.But there were no significant linear relationships between soil silt particles and the contents of SAN and Ammonia nitrogen,their correlation coefficients were 0.361(n=36) and 0.203(n=36).The content of soil sand particles and the contents of Ammo acid nitrogen and Ammonia sugar nitrogen were both highly of significant negative linear relationships,the correlation coefficients were -0.503^** and -0.438^**(n=36).The content of soil sand particles and the contents of STN,SAN and Ammonia nitrogen were all of negative linear relationships,and the correlation coefficientswere-0.555^*(n=36),-0.312(n=36) and-0.284(n=36).