设施菜地种植年限对土壤理化性质和生物学特征的影响

Effects of vegetable planting ages on the physical and chemical and biological properties of greenhouse soils in Beijing

【目的】研究分析北京郊区不同种植年限设施菜地的土壤生态环境、土壤理化性状、土壤微生物数量、土壤线虫群落结构的差异,为不同种植年限设施菜地土壤管理提供科学依据。【方法】以露地土壤为对照(CK),采集种植3年、5年、8年和12年的0—30 cm设施蔬菜土壤样品,采用常规土壤理化性质检测方法测定了土壤的理化性状,采用荧光定量法和线虫形态学鉴定方法,分析土壤细菌、真菌数量以及土壤线虫群落组成。【结果】随种植年限增加,设施菜地土壤容重和pH值均明显下降,总孔隙度、EC值、SO_4^(2–)、Ca^(2+)、有机碳、NH_4+-N、NO^(3–)-N含量均持续升高。与CK相比,种植年限3年、5年、8年、12年的样地土壤细菌和真菌的数量均显著增加(P <0.05)。随种植年限增加,根结线虫属(Meloidogyne)、螺旋属(Helicotylenchus)、异皮属(Heterodera)丰度逐渐增加;土壤线虫密度、植物寄生性线虫丰度显著增加(P <0.05),而食细菌、食真菌、杂食/捕食线虫丰度逐渐降低。线虫群落的多样性H′、SR指数和均匀性J′指数均呈现出先增加后降低趋势,与CK相比,种植年限12年样地的指标值显著降低(P <0.05)。所有种植样地NCR> 0.5,表明样地土壤食物网以食细菌通道为主,土壤有机质以细菌分解途径为主。WI、MI指数逐渐降低,而PPI指数表现出相反的趋势,其中种植年限12年样地WI <1,这表明土壤矿化途径转变为以植物到植食性线虫为主要参与者,土壤生态系统受干扰程度逐渐增强,土壤健康状况变差。土壤环境因子与土壤生物数量间的冗余分析表明,土壤pH、总孔隙度、容重、EC值、有机碳、SO_4^(2–)、NH_4^+-N、NO_3~–-N是影响细菌、真菌和线虫数量的关键因子,不同种植年限设施菜地由于改变这些因素而影响土壤生物群落组成。【结论】连续种植导致京郊设施菜地盐分含量显著升高、养分失衡、土壤酸化。理化性状的变化改变了细菌和真菌数量,进而导致土壤线虫总数、植物寄生性线虫比率逐渐增加,尤其根结线虫属比率增加显著,食细菌、真菌和杂食/捕食线虫比率逐渐降低。以种植12年后的土壤受干扰程度最大,土壤微生态失衡最严重。

[ Objectives ] Vegetable planting ages have different impaction on the soil ecological environments, especially inside green houses. The properties of soil physical and chemical, the population of soil microbial and the soil nematode community structures in the soils under different vegetable plantation age were determined in this paper, aiming to provide reference for the scientific management of green house soil. [ Methods ] The open field was taken as control （CK）, and the nearby greenhouses with planting ages of 3 years, 5 years, 8 years and 12 years were chosen for the research in Yanqing, Beijing. The soil samples at depth of 0-30 cm were collected with four replicates. The physical and chemical properties were analyzed using conventional chemical methods. The population of bacteria and fungi and the composition of soil nematode communities were measured using fluorescence quantitative method and nematode morphological identification methods, respectively. [ Results ] With the increase of vegetable plantation age, soil bulk density and pH value were decreased, whi soil total porosity, EC, SO4^2- , Ca2＋ and organic carbon （SOC）, NH4＋-N, NO3 -N content were increase continuously. The number of both the soil bacteria and fungi showed trend of increasing firstly and then decreasing, and all significantly higher than the CK （P 〈 0.05）. The abundance ofMeloidogyne, Helicotylenchus and Heterodera were increased steadily with the planting ages, and the density of soil nematode and tl abundance of plant-parasites nematode were increased significantly （P 〈 0.05）, while the abundance bacterivores, fungivores, predators/omnivores were gradually decreased. The diversity index of H＇, SR ar stability index of J＇ in nematode communities were increased firstly and then decreased, compared with CK, tl indexes in planting ages 12 year were decreased significantly （P 〈 0.05）. In all the tested fields, the NCR 〉 0. which indicated the soil food web was dominated by bacterial channels, and the decomposition of organic matt depended mainly on bacteria in the study. The WI and MI were decreased gradually, while the PPI showed tl opposite trend, the WI 〈 1 in planting ages of 12 years, which showed that the soil mineralization pathw~ changed into the main participant from plant to plant-parasites nematode, the soil ecosystem was disturbed gradually and the soil health was worse. The redundancy correlation analysis of soil environmental factors and tl number of soil organisms showed that soil pH, soil bulk density, total porosity, EC, organic matter, SO4^2-, NH4＋- and NO3 -N were the key influencing factors on the number of bacteria, fungi and nematode. Therefore, tl composition of soil organisms was influenced by the change of these environmental factors with differe： vegetable planting ages. [ Conclusions ] The continuous vegetable cultivation has significantly increased the sc salt contents, led to nutrient unbalance and soil acidification. The changed soil properties have caused the variatk of soil bacteria and fungi population, and consequently caused the gradual increase in total soil nematodes and tl ratio of plant parasite nematode to predator nematodes, especially the significant increase in the ratio Meloidogyne. In the tested suburbs of Beijing, the highest degree of soil disturbance and the weakest soil micr, ecology is in the field under 12 years＇ vegetable production in the suburb of Beijing.