Leakage And Transportation Of Partial Nutrients In The Soil Treated With Different Water Managements

China, one of the thirteen countries with lowest water supply, is being threatened seriously by water shortage these days. Limited water resource has become one of the main restrictive factors to sustainable agriculture. Traditional waterlogged rice cultivation not only consumed a huge amount of water but also led to some serious environmental problems as a result of fertilizer and pesticide application. Water saving agriculture has evidently become the main development trend to sustainable agriculture. As rice has the adaptation to both water-lodged and aerobic condition, the water saving mechanism, aerobic cultivation of rice is being paid more and more attention. In this thesis, the current condition and the future development tendency of water resource in China are discussed, followed by the importance of developing water saving rice cultivation.A simulation experiment of cultivating rice in both water lodged and upland conditions was carried out to explore the vertical transportation of nitrogen, phosphorus, potassium, calcium, magnesium, manganese, zinc in soil with or without rice cultivation under water-lodged or aerobic condition, and to study the loss of NO3--N, NH4+-N, total phosphorus and inorganic phosphorus in leaching solution.The main results showed that:1. A large amount of NO3--N was leached from the water-lodged soil shortly after fertilizer addition, mainly in the first 18 days. As comparison, there was less NH4+-N leaching which mainly happened in the first 15 days after the treatment. NH4+-N, counted for 98.8 % of total N leaching, composed of most nitrogen leaching in absolute number. Similar to NH4+-N, total phosphate and inorganic phosphate leached the most during three to 15 days after fertilization. In water lodged condition, less leaching of NH4+-N, total phosphate and inorganic phosphate, while more of NO3-N and organic phosphate were observed in the treatments with rice growing than those without. NO3-N leaching was much higher when rice was present. The total concentration of nitrogen and phosphorus from different soil layers were lower in waterlogged treatments than in upland treatments. During the growing season, 55.2% of all samples had higher NO3-N concentration than the pollution standard, 10 mg/L of NO3--N. The total phosphorus, varied from 0.37mg/L to 0.034mg/L during this period, also exceeded the pollution standard 0.02mg/L[2,3,4]2 .Under the water-lodged cultivation, calcium and magnesium, especially calcium tended to leach away easily. Compared with the water lodged rice cultivation, the contents of water-soluble magnesium, exchangeable magnesium and water-soluble calcium available potassium were significantly higher in soil under aerobic rice cultivation.3 Under waterlogged cultivation,there was a large amount of leaching of manganese while relatively less zinc leaching. Planting rice could improve the activity of soil manganese and zinc. The concentrations of available manganese and water soluble manganese in all soil depths were higher in upland treatment than those in water-lodged treatments, while there was no difference in available zinc. In both water-lodged and upland conditions, soil available manganese accumulated significantly with the increase the soil depth, which was not the case for soil available zinc. Rice cultivation helped to increase the availability of soil zinc and manganese in both water lodged and upland conditions.