Research On Nitrogen Transformation In Soils With Different Acidification Level

Black soil has good physical and chemical properties and high soil fertility. However, in recent years, human's exploitation and utilization of black soil caused serious soil degradation, and acidification is one of the main forms of soil degradation. Acidification changed the habitat in soil and influenced the nitrogen transformation process. Soil samples were collected from a long-term experimental field on the campus of the Heilongjiang Academy of Agricultural Sciences, Harbin, Heilongjiang province. Laboratory incubation was used to study the differences of mineralization, nitrification potential, enzyme activity, microbial biomass and respiration in different soil pH, and further explore the specificities of nitrogen transformation and microbial activity in different acidification, which provide theoretical support for rational fertilization and environmental restoration of acidification.There were significant differences in mineralization and nitrification potential in soils with different pH. Because soil microbial activity was the strongest in pH7, mineralization (8.16 mg kg-1) and nitrification potential (30.1 mg kg-1 d-1) were the strongest in this condition and higher than other pH treatment. The soil enzyme is a sensitive biological indicator which could indicate disturbance of soil. The urease activity of black soil remained at a relatively high value, while the dehydrogenase activity was increased with the increase of pH, but only in a narrow pH range. Microbial biomass carbon and nitrogen could be used not only as soil organic matter and power of soil nutrient transformation and cycling, but also as available nutrient pool of plant. And they could be quickly converted, show a great difference before the detection of changed total carbon and nitrogen. They were sensitive ecological indicators. Soil microbial biomass carbon (218.8 mg kg-1) and nitrogen (39.9 mg kg-1) were the largest in pH7, the content changed with pH value. Soil respiration is an important process of carbon cycling in farmland ecosystem, and also a main output of soil carbon pool. It is usually used as indicator of soil biological activity, soil fertility and soil permeability. CO2 emissions peak of natural soils in different pH value appeared within 24 hours after incubation, followed by various CO2 emissions in different soil pH which illustrate the differences of soil respiration in different acidification soil.