Study On The Correlation Between Black Soil Bacteria And Soil Carbon And Nitrogen In Typical Farmland

Long-term Spatial Transplantation Experiment of Mollisols Productivity was used in this study, which contains Mollisols of 5 soil organic matter(SOM) levels, namely SOM 11%(Bei’an, Heilongjiang Province), SOM 6%( Nenjiang, Heilongjiang Province), SOM 5%( Hailun, Heilongjiang Province), SOM 3%(Dehui, Jilin Province) and SOM 1.7%(Lishu, Jilin Province). Maize was planted on the Mollisols from 2013 to 2014. The changes of functional bacteria and their relationships with soil nutrients such as soil organic carbon and nitrogen were studied and the results are as follows:1.Physiology functional bacteria in Mollisols of 5 SOM levels changed as described below: bacteria accounts 80% for total microbial biomass, and the volume of bacteria increased with the increasing of SOM. The amounts of ammonifying bacteria, nitrifying bacteria and denitrifying bacteria, respectively 1.92~2.81*104 units g-1 soil, 0.92~2.74 *104 units g-1 soil and 0.59~2.03*104 units g-1 soil, increased with the increasing of SOM. However, the amounts of nitrite bacteria, ranged from 0.59~3.17*104 units g-1 soil, decreased with the increasing of SOM.2.Soil nutrients in Mollisols of 5 SOM levels changed as described below: ammonium nitrogen, available nitrogen, fixed ammonium, microbial biomass nitrogen and soil organic nitrogen declined with crop growth period prolonging, with the fluctuant ranges 9.18~36.81mg/plot, 41.82~87.43mg/plot, 5.86~27.01mg/plot, 3.21~19.55mg/plot and 5.55~22.90mg/plot, respectively. Nitrate nitrogen increased with crop growth period prolonging, ranging from 13.49 to 62.18 mg/plot.3.Using SAS software, through correlation analysis and path analysis were done. The results show that the soil organic carbon, total nitrogen, ammonia nitrogen, nitrate nitrogen, fixed ammonium and microbial biomass nitrogen displayed significant or extremely significant correlation with ammonifying bacteria, nitrifying bacteria and denitrifying bacteria. Direct effects to total nitrogen were in the order: ammonifying bacteria(0.456), denitrifying bacteria(0.274) and the nitrifying bacteria(0.109),Denitrifying bacteria(0.139). Direct effects to SOM were in the order: ammonifying bacteria(0.334), nitrifying bacteria(0.180), denitrifying bacteria(0.160) and the nitrifying bacteria(0.078). Nitrifying bacteria had larger direct effect on organic nitrogen, nitrate nitrogen(0.025 and 0.025) and ammonifying bacteria had larger direct effect on the fixed ammonium, microbial biomass carbon and nitrogen(0.258, 0.661 and 0.258).