Effects Of Different Planting Years On Soil Microbial Community In Facility Field

Soil degradation in greenhouse field with the extension of planting years has caused widespread concerns.In this study,the greenhouses with different planting years in Qingxian County of Hebei Province were selected as the research objects,and the soil samples were collected from the facility field with continuous planting years of 2,4,10 and 12 years.The main physical and chemical characters,soil enzyme activities,soil microbial biomass carbon and nitrogen were determined.Based on phospholipid fatty acid(PLFAs)method,the total amount of soil microbial PLFA,and the PLFA index of soil microbial community components such as bacteria,fungi and actinomycetes were characterized to determine the composition of soil microbial communities.The changes in soil nutrient and microbial community composition and structure with increasing planting years and the correlations between soil physical and chemical properties with microbial community components were analyzed.These results would provide basic data for the elimination of continuous cropping obstacles in greenhouse field and the promotion of sustainable development of facility planting.The main results were as follows:1.With the planting years increasing,soil electric conductivity and nitrate nitrogen content increased significantly,but the soil microbial biomass nitrogen decreased.2.Soil urease activity,catalase and invertase activities were not significantly different with the increase of planting years.3.The soil microbial community structure changed significantly with planting years increasing.The total amount of soil microbial PLFA and the amount of bacterial PLFA decreased with the increase of planting years.The decrease of total microbial PLFA and soil bacterial PLFA was positively correlated with soil microbial biomass nitrogen.The reduced supply capacity of nitrogen in soil was an important cause of the decrease in soil bacteria number and the total amount of microorganisms.The Gram-negative bacteria significantly reduced,but the degree of soil salinization increased with planting years increasing.