Analysis of Main Soil Factors Limiting Vegetables Production under Greenhouse in Jinning County

Five years planted soil was used to find the main factors limiting greenhouse vegetable production in the method of wild investigating combined with chemical analysis and mathematical statistics in Jinning County, Yunnan Province.The distribution of greenhouse vegetable soil nutrients, pH, EC, CEC in different soil layers(0~10 cm, 10~20 cm and 20~30 cm) and the relationship between these factors and vegetable yield were studied, the main soil factors limiting vegetable yields were found out. The results suggested that:(1) Distribution of soil nutrient content was significantly vertical and accumulation in 0~10 cm lever. Soil acidification and secondary salinization were mainly concentrated in 0~20 cm soil layer. (2) Soil pH was positively correlated with vegetable yield (n=39,r=0.462**)while EC had negative relationship with crop yield (n=39,r=-0.448**). Soil pH and EC were the most limiting factors in vegetable production. (3) Nitrogen fertilizer inputs significantly correlated with soil EC (n=39, r=0.802**) and soil acidification (n=39,r=-0.759**), and increased amounts of nitrogen inputs significantly speed up the process of soil acidification and secondary salinization.In order to reduce the risk of soil acidification and secondary salinization under plastic tunnel and improve the production, we suggested that decrease fertilizer inputs (particularly nitrogen) while increasing organic fertilizer application in this region. Aimed to provide a reference basis of scientific nutrient managements and promoting sustainable development of facilities vegetable soil and production.