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野外调查与室内分析表明,位于长江三角洲嘉兴市的稻麦轮作田改为多年连作的蔬菜保护地后,土壤肥力质量已出现明显的酸化、次生盐积化、“富营养化”和非均衡化(氮磷超负荷累积和中微量元素缺乏)等演变趋势。与第二次土壤普查时的同类蔬菜地土壤相比,或与仍是稻麦(油)轮作的三类代表性水稻土相比,153个蔬菜保护地土壤样品pH平均下降约0 9单位。囊水型水稻土和爽水型水稻土大棚保护地的土壤pH下降严重,而漏水型水稻土大棚保护地只略有下降。84个蔬菜保护地土壤样品的可溶性盐平均为2 81g/kg,其中>3 0g/kg占36 2%。囊水型土壤含盐量最高,达3 71g/kg,爽水型土壤与漏水型土壤分别为2 67和2 54g/kg。土壤有机质、全氮、速效磷、速效钾均有大幅增加,尤其是速效磷超负荷累积:硝态氮(N)>300mg/kg占调查样品的30 8%,速效磷(P)达90mg/kg以上。但中微量元素相对不足,缺钙、缺锌、缺硼等生理缺素病害时有发生。调查证明,蔬菜保护地土壤肥力质量急剧变化与过量施肥及多年大棚蔬菜连作有关。因此,退化土壤的修复必须从建立科学的平衡施肥制度和合理的轮作倒茬体系着手。
Field investigation and laboratory analysis showed that the quality of soil fertility had obvious acidification, secondary salinization, and “eutrophication” after the rice-wheat rotation field in Jiaxing City in the Yangtze River Delta was changed to a continuous vegetable reserve. Non-equilibrium (accumulation of nitrogen and phosphorus overload and lack of trace elements) and other evolution trends. Compared with the soil of the same vegetable in the second soil survey or the three representative types of paddy soil still in the paddy and wheat (oil) rotation, the average soil pH of 153 vegetable soils decreased by about 0.9 units. The soil pH of the capsule-type paddy soil and the Shuishui-type paddy greenhouses protected the soil to drop seriously, while the water-tight paddy-soil greenhouse protection area only declined slightly. Soil samples from 84 vegetable soils showed an average of 2 81 g / kg of soluble salt, with> 30 g / kg accounting for 36.2%. The soil salinity of the capsule-type soil was the highest, reaching 371 g / kg, while the fresh and leaking soil was 2 67 and 254 g / kg, respectively. Soil organic matter, total nitrogen, available phosphorus, and available potassium all increased significantly, especially the overload of available phosphorus: nitrate (N)> 300mg / kg accounted for 30.8% of the surveyed samples, available phosphorus reached 90mg / kg or more. However, the relative lack of trace elements, calcium deficiency, zinc deficiency, lack of boron and other physiological deficiency diseases have occurred. Surveys prove that the rapid changes in the quality of soil fertility in vegetable reserves are related to over-fertilization and continuous cropping of vegetables in greenhouses. Therefore, the restoration of degraded soils must start from the establishment of a scientific balanced fertilization system and a reasonable rotation system.