Study on Soil Nutrient Variation and Salt Accumulation Characters in Vegetable Greenhouse

[Objective] The purpose was to solve the problems such as vegetable pests and diseases aggravating,yield decreasing and quality becoming inferior directly caused by high salt content in cultivated layer in the greenhouse with long term and obvious change of microbe composition.[Method] The soil nutrient variation and salt accumulation situation in greenhouse with different cultivation years in Huaian city of Jiangsu province were studied.[Result] The alkaline hydrolytic nitrogen amount in all the greenhouses was over 140 mg/kg.Compared with 1-year-old greenhouse,the quick-acting phosphorous content in 4-year-old greenhouse increased 48.56 mg/kg.Compared with 2-year-old greenhouse,the quick-acting phosphorous content in 3-year-old greenhouse increased 13.52 mg/kg.The available potassium(K) amounts in 3-year-old and 4-year-old greenhouses were 96.88 mg/kg and 138.4 mg/kg respectively.The pH value of soil was 5.12 and the water soluble salt content in top soil achieved 4.62 g/kg in 4-year-old greenhouse.[Conclusion] The available nutrient content of soil in greenhouse was higher than that of open field and increased in 0～20 cm soil layer along with the cultivation years increasing.The pH value of soil was acidified to some extent in 4-year-old greenhouse and the water soluble salt content was obviously higher in the greenhouse than that of neighbor open field,and the majority had achieved the mid-degree of salt harm.