Effect Of DMPP On Nitrifying And Denitrifying Bacteria In Paddy Soils

A systematic research was made on the DMPP for its effect on the nitrification and denitrification bacteria in the paddy soil. Through the experiments, different dosage DMPP were added into the two soil (qingzini, huangbantu), the typical Taihu Lake Basin paddy soils. Analysed the different changes in the number of nitrifying bacteria (ammonia-oxidizing bacteria and nitrite-oxidizing bacteria) and denitrifying bacteria in the soils by MPN count, and research the changes in the baterial flora (community structure and the diversity) by the method of polymer ase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). According to the research, revealing the mechanism of DMPP in nitrogen microorganism in the paddy fileds. The main conclusions were as follows:(1) DMPP had the remarkable inhibitory effect of the number of ammonia oxidation bacteria in test paddy soils, which the1%DMPP added processing put up the most stable inhibitory effect.The number of ammonia oxidation in the1%DMPP treatment to CK treatment, respectively, reduced78%,57%,78%,74%in qingzini,62%,80%,78%,78%in huangbantu, and the inhibitory effect reached a significant level. Under the same conditions, DMPP achieved better inhibitoy effect in huangbantu than in qingzini. DMPP had no significant influence in the bacteria community impact of ammonia oxidizing bacteria in the tested soils.(2) DMPP had no influence on the numberof nitrite-oxidizing bacteria in qingzini and huangbantu, which can infer that DMPP also by inhibiting the process of NH4+oxidation to NO2-to achieve inhibition effect of nitrification. The analysis on the community structure of nitrite-oxidizing bacteria, indicated DMPP can selectively affected some bacteria to affect community structure of nitrite-oxidizing bacteria in the tested soils.(3) DMPP had no influence on the number of denitrifying bacteria in qingzini and huangbantu, but affected the community structure of denitrifying bacteria in the soil for trial. The diversity of denitrifying bacteria had a notable decreaseing when0.5%DMPP was added in qingzini, so did0.75%DMPP was added in huangbantu at the onset of experiment, and the influence reduced as the DMPP effectiveness reducing. DMPP caused great changes of denitrifying bacteria in the aspect of bacteria structure, and to a certain extent. The amount of the addition of DMPP had a negative correlation affect on the similarity, and the effectiveness decreased with DMPP effectiveness weakened, but CK and1%DMPP treatment similarity is still less than60%to the end of the experiment.