Nutrient Accumulations In Soil And Its Management With Water Under Sunlight Greenhouse Cultivation

In recent years, cultivating the vegetables with protected facilities such as sunlight greenhouses has developed rapidly in China, and these cultivations have become an important component of modern agriculture. Development of protected cultivation of vegetables has tremendous impetus not only in developing of rural economy but also in increasing farmer's income. However, beause of the lack of effective water and fertilizer management, excessive fertilization and irrigation are very common in production. It not only causes the waste of fertilizer and water, but also declines the quality of fruits, and deteriorates the soil environment. Many researchers have explored the way to use the fertilizer and water effectively now. In this research, we study the accumulation of nutrients in the soils under the sunlight greenhouses in Shaanxi Province, and to evluate the effects of different water and fertilizer managements on the growth of tomato and on the nutrients and water use efficiency. The following conclusions are drawn:1.The application of fertilizers in the sunlight greenhouse in Shaanxi province was very common, especially nitrogen fertilizer. The average application rate of nitrogen fertilizer in Yangling, Ba qiao district of Xi'an, and An Sai was higher than 600 kg/hm2. Successive and over-added use of the fertilizers induced the nitrate, available P and K content in the soils. Electric conductivity (EC) in the soil in sunlight greenhouse was much higher than that in cropland. In An Sai, EC in the soil in sunlight greenhouse (0.70 mS/cm) was 4.12 times of that of cropland (0.17 mS/cm). It is clear that excessive use of fertilizer, especially nitrogenous fertilizer, was the main reason of causing the high electric conductivity in soils. There was significant correlation between the accumulation of soil nitrate and EC of soil, indicating the important role of nitrate in increasing salt accumulation in soils. In addition, the rising of EC in lower soil layers indicates that the large movement of nutrients, especial nitrate.2.Compared to the practical methods using fertilizer by farmers in the region, the prescription fertilization treatment decreased the amounts of fertilizers added, did not induced the reduction of the tomato yield; furthermore, the quality of tomato fruit was improved. When the application of fertilizer was similar, water saving irrigation reduced 22.1% of irrigation rate, but did not show negative effect on the yield and quality of the tomato relative...