| China is the major agricultural country in the world, where the agricultural field is an important source of soil N2O emission. Taking positive and effective measures to reduce emissions from soil is of far-reaching importance for the ecological agriculture and the reduction of agricultural pollution as well as the greenhouse gas emissions.This work aimed to seek possible beneficial or antagonist microbes which can supress greenhouse gas N2O emission from soil. Importantly, developing this biotechnology of mitigating greenhouse gases and explorating their mechanisms are of the great scientific value and the broad application prospect.The main results were as follows:Two strains better effecting on soil N2O emission were obtained from potential strains twice in a lab, which was coded as F22, Z17. The results showed that a N2O emission reduction reduction of 58.02%, 47.16% was obtained in the concentration of 108 cfu·g-1 for F22and 107 cfu·g-1 for Z17 compared with controls respectively. It was significantly to reduce the soil N2O emission. By identifying the morphological,physio-chemical and molecular biological (sequence blast in GenBank)characteristics of two strains, they were identified as Actinomycete F22-Aeromonas media, and fungus Z17- Trichoderma asperellum.The optimal growth temperature of strain F22, Z17 were 35℃,and pH 7-9 was the best growth condition. The strains F22 and Z17 were all able to grow on the 7 kinds of culture media, PDA and denitrifying bacteria enrichment medium was the best for F22, PDA and LB medium was for Z17. The optimal temperature of conidia production was 25…30 ℃ for Z17, and the optimal pH was 7 for the mycelial growtht, while the count of spores I was the largest for pH 6.The effects of different environmental factors on N2O emission were obvious.The cumulative N2O emission from wheat and forest soil was higher than that from vegetable soil, increment of 39.24%, 60.20% respectively. Compared with CK, the N2O emissions from soil mixed with rice and wheat straw powders were increased by 23.63%, 18.09% respectively. However, garlic straw powder had a significant reduction effect on soil N2O emission (F=120.077, df=3, p=0.000). Fertilization increased the soil N2O emission flux, but it was not significant for different fertilization.Soil enzyme activities were measured when adding microbial nitrifing inhibitors.The results indicated that microbial nitrifing inhibitors inhibited Solid-Neutral Protease(S-NPT), Solid-cellulase(S-CL), Solid-Nitrate Reductase(S-NR) activity, especially significantly inhibiting Solid-cellulase(S-CL) and Solid-Nitrate Reductase(S-NR). The Solid-Neutral Protease (S-NPT), Solid-Urease(S-UE), Solid-cellulase (S-CL), Solid-Nitrate Reductase(S-NR) enzyme activities from vegetable garden soil were lower than those from forest and wheat soil. By adding garlic straw powder to the soil, the N2O emission was decreased, where the soil S-NR, S-NPT activities were significantly decreased (F=251.077, df=3, p=0.000; F=145.459, df=3, p=0.000), while it has an inhibitory effect on Solid-Urease(S-UE), Solid-cellulase (S-CL) and Solid-a-Glucosidase(S-alpha-GC) enzyme activity. Different nitrogen fertilizer had different influences on different soil enzyme activity, but the trend was not so obvious. It was concluded that microbial nitrifing inhibitors restrained nitration, nitrification and denitrification in the soil, decreased N2O emissions, demonstrating a theoretical and technical support for prevention and control of global climate change. |
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