Coupling Effect Of Irrigation And Nitrogen On Soil Salinity And Its Ion Composition In Greenhouse

Because the production facilities are in closed or semi-closed conditions, and soils lack of rain for a long-term, soil secondary salinization problem occurs frequently. Reasonable regulation of the supply for water and fertilizer can effectively promote crop growth and prevent soil degradation. Therefore, this article is based on two factors (the usage amount of nitrogen fertilizer and the lower control limit of irrigation) and the experiment was repeated three times, to design the tomato field plot experiment completely randomly. After researching the different lower limit of irrigation and different usage amount of nitrogen fertilizer’s influence on soil total salt content which planting for three years, I arrived at the correct ratio of water and nitrogen fertilizer to manage this soil. Preventing soil degradation and achieving high yield and quality of crops as the theoretical basis, my main conclusions are as follows:1. Total salt content of the soil is mainly affected by the usage amount of nitrogen fertilizer, and when the lower limit of irrigation is certain, the total salt content of soil and the usage amount of nitrogen fertilizer positively correlated. Soil total salt’s accumulation is significant between years, and with soil depth, the cumulative total salt content is more obvious, but the group subtotal’s salt for each year which in 35kPa lower limit of irrigation through much fertilizer processing has the highest cumulative.2. Different water and nitrogen treatments have different influence on soil environment. There are significant differences between each occasion, each soil, the various irrigation water as well as the fertilizer rate and soil soluble salts (except sulfate).3. Soluble salt ion accumulated among different interannual apparently. With anion accumulation increased, soil pH are getting lower, and nitrate accumulation is in multiples of maximum growth. And the soluble salt content get highest for each year which in 35kPa lower limit of irrigation through much nitrogen treating.4. Soil EC increases with the increase of fertilizer rate and decreases with the soil depth deepen, and the EC of the soil is highest in each year under 35kPa lower limit of irrigation through much fertilizer processing.5. Under 35kPa lower limit of irrigation in each year, using moderate amounts of fertilizer can get maximum yield, while using a small amount of fertilizer can get minimum yield under 25kPa lower limit of irrigation. Adequate limit of irrigation and the amount of nitrogen can ensure the highest yield.The accumulation of soil salt was affected by irrigation and fertilization together, and the effects of fertilizer rate is greater than the amount of irrigation water. In this study, irrigation is controlled in lower limit of 35kPa, and soil soluble salt ion accumulation gets maximum after high nitrogen treatment. Controlling the irrigation of 35kPa limit, middle nitrogen treatment can get highest yield.