Effect Of Soil Surface Electric Field On Microbial Activity In Acid Soil

Soils mineral composition of the soil is the most basic materials, combined with other factors determine the nature of the soil surface. Since the surface of soil particles with a large amount of negative charge in solution near the soil particle surface and which form a"continuous" distribution of the strong electric field, on the H+,NH4+,and soil (with a negative charge) have an impact on the nitrification process. In previous studies, few people consider the role of electric field of the surface of soil particles; soil particles from the surface of this electric field strength of different angle of soil microbial activity.This experiment used the soil in Jinyun Mountain pine (Acid Yellow pH 5.2), in soil samples by adding 3%,5%,8%,10% and 12% concentration of montmorillonite treatment, air-dried, crushed through 1mm sieve to be use. At the same time according to the sample resulting from the incorporation of montmorillonite pH changes, thereby developing into samples of different pH. Regulate the two kinds of sample moisture content to 50% of the field moisture content, constant temperature incubator at 25℃in the first month of pre-culture, one month after pre-incubation of soil samples we added the equivalent weight of 100mg/kg dry soil NH4+ -N, NH4 +-N added after the sampling time, and then soil samples placed in the 25℃constant temperature incubator, samples were cultured once a weeks for 4 times Sub-samples were obtained by measuring microbial biomass C and N, urease activity, dehydrogenase activity, and achieved the following results.The surface of soil particles under different electric field strength changed the soil microbial biomass. Soil particle surface electric field under different soil microbial C and N had the same changes-first took an upward trend then decreased, with a maximum value at 14 days. The addition of a certain amount of NH4 +-N to the soil increased the soil microbial activity, increasing soil microbial biomass, but because micro-organisms increase and NH4 +-N decrease within a certain period of time the different kinds of nitrifying bacteria go into competition for food,thus reducing the amount of microbes which results in a reduction in microbial biomass as well.After 28 days, soil microbial biomass first took an upward trend then decreased with an increasing surface electric field of soil particles. As the surface electric field reaches -83.5*107 J/m·C microbial becomes the largest. As the soil of the nitrifying bacteria in the 10-1000 nm in size between the colloidal particles of soil take some considerable negative charge, soil colloidal particles must exist between the van der Waals force and electrostatic force, the nitrifying bacteria activity of the soil particle surface electric field by have a greater impact. As the soil particle surface electric field intensity, the soil nitrifying bacteria have certain attraction, when the community reaches a certain amount of nitrifying bacteria, the microbes and soil particle surface electric field will have a certain attraction, resulting in soil microbial biomass reduction. These inferences need the determination of the future of the microbial community to supplement.Soil enzyme activity:The surface of soil particles under different electric field strength changes in soil enzymatic activities in urease activity were as follows:When the electric field increases urease activity decreases for the first increase and then decrease afterwards, which is the same trend of microbial biomass, adding NH4 + -N to the soil impact. Soil dehydrogenase were as follows:dehydrogenase activity under the influence of surface electric field converge at same point, for the 2.6mg·kg-1·d-1. Dehydrogenase activity of treated sample is much less than that of the original sample, because of the soil treatment process including pulverizing,sieving, which decreased the soil porosity and respiration. Soil dehydrogenase and soil respiration had a significantly positive correlation., therefore dehydrogenase was significantly smaller.In the control test, soil samples at different pH of the index did not change significantly due to changes in low soil pH range. Dynamic changes in the time of surface electric field with the same changes, cultured after 28 days compared to data of microbial biomass in the pH=5.20MBC to 571 mg/ kg pH=5.51 to 678 mg/kg pH=5.68 to 772 mg/kg pH=5.87 to 760 mg/kg pH=5.95 to 787 mg/kg pH=6.04 m for the 796 mg/kg, microbial biomass C with the pH of the small growth in the fast-rising pH at pH=5.20MBN to 62mg/kg pH=5.51 to 68 mg/kg pH=5.68 to 74 mg/kg pH=5.87 to 75mg/kg pH=5.95 to 77mg/kg pH=6.04 m for the 82mg/kg, microbial biomass N increased slightly with pH, giving rise to slow growth. Between pH 5.20 and 6.04, urease, dehydrogenase activity are not very different.These results suggest that, in soils with different concentrations of montmorillonite, the surface of soil particles increases the electric field strength, due to the surface of soil particles with a large negative charge.Negative charge density increased, with a negative charge of the soil having a certain repulsion to reduce the number of soil microbial nitrification, in addition to the soil particle surface electric field on microorganisms. In the preparation of sub-samples of finely ground soil, microbial community structure is destroyed. In addition, natural soil particles have a certain impact on soil nitrification, in which soil organic matter on soil nitrifying bacteria was inhibited. Because soil is more complicated by environmental factors, soil particle surface electric field strength, the specific degree of nitrification, need further investigation.