Effect Of Combine Herbicide On Nitrogen Transformation In Soybean Soil

Chemical weeding techniques of modern agricultural production was an important measure to improve crop quality and yield. During the application of herbicides, it would cause serious pollution on soil ecological environment, one of the most serious phenomenon was soil fertility reduction. Nitrogen was an important component of soil fertility, nitrogen in soil was transformed and circulating through physical, chemical and biochemical processes, the effect of nitrogen on plant utilization and soil loss was the most important biological index of soil quality.. Therefore, the field commonly used variety suinong 26, which were studied in order to discuss different concentrations of mixed application of herbicides effects of soil nitrogen biological nitrogen fixation, nitrification-denitrification process, and ammoniation process. Explored the impact of herbicides on soil nitrogen transformation mechanisms, to provided a reference for reducing herbicide damage. Through the experiment, the following conclusions are obtained:1. After the application of different concentrations of herbicide, the number of soil azotobacter and nitrogen fixing capacity showing the trend of lower first and then increased. It showed that soil have some cushion with herbicides, with the growth changes, the number of soil azotobacter gradually recover. At different growth stages, effect of herbicides on soil azotobacter and nitrogen fixing capacity also showed significant dose-effect, so control of concentrations is necessary. Therefore, in farm production practices, we should minimize the amount of herbicide. From the results of this study, when applied in the field, recommends applying is the recommended minimum concentrations(3.0 L/hm2).2. With different concentration herbicide applicatied, high concentrations of mixed herbicides on the number of soil azotobacter shows a certain amount of irritation, but the soil nitrogen fixing capacity was inhibited about herbicide application. With herbicide applicatied, provide azotobacter certain nutrients and good environmental conditions, azotobacter in the case of nutrient-rich soil, unable to play its nitrogen-fixing ability.3. With different concentration herbicide applicatied, the number of soil nitrification bacteria, content of soil nitrate nitrogen increased, capacity of soil nitrifying were activated. The number of soil denitrifying bacteria were no apparent or reduced after application of different concentrations of mixed herbicides. After the herbicide into the soil, to a certain extent, played the role of nitrification inhibitor. But the increase of the number of soil nitrification bacteria, content of soil nitrate nitrogen, the reduce of the number of soil denitrifying bacteria were good for soil nitrification.4. With different concentration herbicide applicatied, soil ammoniation process were inhibited. Instructions when mixing herbicide use, control of concentrations is necessary. Although under high concentration, affected of the number of soil ammonifiers was small, the activity of protease was activated, but overall, capacity of soil ammonifying were inhibited. Therefore, in farm production practices, should be minimize the amount of herbicide. From the results of this study, when applied in the field, recommends applying is the recommended minimum concentrations(3.0 L/hm2).In conclusion, this study suggests that, when the concentration is less than the recommended dose of herbicide, had no significant effect on soil nitrogen transformation processes, when the herbicide concentrations higher than the recommended dose, and had a certain influence on soil nitrogen transformation processes. Therefore, herbicide application process, must be strictly controlled dosage of herbicide to prevent herbicide remaining soils, harmful to soil fertility. Soil nitrogen cycle is an extremely complex process, herbicide application, and does have an impact on other biological indicators of soil also needs further research, thereby controlling the key process of nitrogen cycle, reducing herbicide damage.