1.土壤酸害。连作蔬菜大棚由于长期施用生理酸性肥料,过量施用氮肥,使硝态氮大量积聚,同时有机肥施用又偏少,土壤缓冲性差,因而使土壤酸化,严重时作物会出现死苗,生长点坏死等现象。2.土壤盐渍化。蔬菜大棚全年土温较高,加之较高的湿度,土壤微生物活动旺盛,加速了土壤养分转化和有机物质的分解,同时由于常年不合理的过量施肥,又缺少雨水淋溶,使残留在土壤中的各种肥料盐分随浇灌水向耕层积聚,形成次生盐渍。据测定, 1. Soil acid damage. Because of long-term application of physiological acid fertilizers and excessive application of nitrogen fertilizer, continuous cropping of vegetable greenhouses causes a large accumulation of nitrate nitrogen, while the application of organic manures is too small and the soil bufferability is poor, thus making the soil acidified. In severe cases, dead seedlings and growth point necrosis will occur in crops. phenomenon. 2. Soil salinization. Vegetable greenhouse temperature is high throughout the year, combined with high humidity, soil microbial activity, accelerating the conversion of soil nutrients and organic matter decomposition, and perennial unreasonable excessive fertilization, but also the lack of rainfall leaching, the residue in the soil In a variety of fertilizer salts with irrigation water to the accumulation of plow, the formation of secondary salinities. According to the determination,