Study on fertilization techniques for greenhouse vegetable in Shanghai suburbs

Protected (greenhouse) vegetable land has developed quickly in recent year in Shanghai suburbs to increase farm productivity. According to 2010 statistics, including 9 districts and Chongming county and Guangming Food Corporation, Shanghai already has more than 13,501 ha of horticultural facilities (greenhouse). However, many problems such as secondary salinization, acidification in vegetable greenhouse soil have become more and more serious. About 30% of the greenhouses soils have suffered stress of secondary salinization. Soil secondary salinization is the main reason for limiting vegetable production in greenhouse in Shanghai suburbs. In order to study the influence of soil salinity on vegetable, greenhouse pot experiments were conducted in 2011 by the Soil and Fertilizer Institute, Shanghai academy of agricultural Sciences. Hoagland nutrition liquid was used in these experiments as nutrient resource.

Results indicated that excessive fertilization resulted in salinization, which inhibited and harmed the growth of the vegetables. The damage of soil secondary salinization to vegetable mainly occurs at the seedling stage with germination rate and/or survival rate of seedling. Under normal circumstances, the threshold limit at which soil salinity can harm vegetable seedling was found out to be 3.0 g/kg. Vegetable seedlings would be seriously harmed when the content of soil salinity reached 6.0 g/kg. Shanghai-09