The Study On Nitrogen Supply Of Soil After Long-term Different Fertilizing Experiments

This study was conducted at the long梩erm location test station of Chinese Agricultural University. The experimental soil samples (N0P0,N,P0, N2PQ, 2~ 2? 2K, NQPQM, 1~ N2PQM, NQP2M, N,P2M, N2P2M, N2P2K M)of which the chemical fertilizers and chicken dung have been applied for 14 years were used for the experiment. There are several influences factors on the N variations in the soil were studied. 1) The influences of oven temperature (400C, 600C, 800C and l050C), extracting temperature (400C, 600C and 800C) and extracting time (0. 5,1,1. 5, 2, 4, 6, 8 and 10 hours) on the levels of ammonia nitrogen(NII4~), nitric nitrogen(N03), easy mineralizing organic nitrogen(N梠rganic) were studied. 2) the pot cultivation method was used for the study of the influences of biological efficiency of N梠rganic, microbial nitrogen biomes(SMB桸) and different forms of fertilization on the level of SMB桸 in the soil were also studied in the experiment. 3) N? tracer technique was applied to study the interaction between soil N and Fertilizer N,and 4)green house cultivation experiment was carried out for investigation of the influences of inhibitor(DCD) on transition of soil nitrogen. Through studying the influence of different oven drying temperatures, extracting temperatures and times of 14 soils on ammonia nitrogen, nitric nitrogen, easy mineralizing organic nitrogen and its biological efficiency, The following results were attained: the quantity of soil extractable organic nitrogen increased with the increasing of oven drying temperature from 400C, 600C, 800C to 1050C. The results of multiple comparison were c,c,b and a(p<0.05). The determinant coeffiency (r2) of soil organic nitrogen and uptaking桸 of wheat plant were 0. 0835, 0. 0689, 0. 7862 and 0. 7661, respectively, only the correlation coefficiency was significant between the treatment of 800C and 1050C;At the extracting temperature of 800C, the organic nitrogen increased within the beginning 2 hours and went to stable late, the determinant coefficient of the quantity of soil nitrogen and uptaking桸 was significant(r2~0.7755).The above two ways had the same influence on 5 ammonia nitrogen and nitric nitrogen, that was with the increasing of temperature, quantity of ammonia nitrogen increased while nitric nitrogen抯 decreased. The study of soil nitrogen supply potentiality of 14 soil treatments under the biological experiment condition of supplying no fertilizer or only supplying phosphorous and potassium fertilizer showed that only nitric nitrogen and total nitrogen content could reflect the soil nitrogen supply capacity well when different kind of nitrogen forms in foundation soil sample or in soils of before and after the biological experiment were used to evaluate the nitrogen supply capacity, it determinant coefficient was significant(p