Investigation On The Effect Of Controlling The Non-point Source Pollution By Shallow Wet Irrigation

With the development of society, the non-point source pollution problems in environment are quite obvious. It brings prodigious influence on the livelihood and production of man. It has become one of the lead study projects faced by every country scholar in the world. The Nantong is a base of paddy rice production, the water used for the paddy field irrigating annually account for 53.5% of the whole municipal gross used water .It is not only wasting the resources of water, but also resulting in serious non-point source pollution .For alleviating the great city water antinomy between the need and lack with fresh water, and the antinomy between the economic performance and ecosystem performance, put forward to change traditional full wet irrigation to the saving water irrigation. The test researched some irrigation patterns and compare the Organism matter content, total Phosphorus content , the available Phosphorus content , Potassium content, total Nitrogen content , the paddy product, economic performance and ecosystem performance with difference irrigation during the culture by studying the irrigation water and the Osmosis water and the Drained away water. Obtain the conclusions as the next:1. The indexes are not so different obviously before culture, chemicals change with the depth of the soil .the Statistics shows that Organic matter , Nitrogen, available P, K of soil have the exceedingly correlation relationship with the soil depth.2. The drainage from shallow wet irrigation has higher concentration in Nitrogen than that from flood irrigation , yet water amount consumption and placing in shallow wet irrigation are 40% and 31% less than flood irrigation , therefore shallow wet irrigation loses less than flood irrigation in the unit area;3. It can be seen clearly that in the three drought absorptions, underground water level has obvious influence on the rice production and the absorption of phosphoric;4.Under the shallow wet irrigation, both the exploitation efficiency of the soil available phosphoric and the contains of phosphoric in rice are higher; but in other absorptions that have wet-drought changing steps, the element phosphoric can be changed easily from fixing appearance to available appearance, but it can also run off easily;5. Analyzing the total N content and the available P content, and other elements of the paddy flora apparatus, seed has more than others, secondly is the straw, the order is seed > straw.6:The non-full irrigation, shallow wet irrigation, full irrigation and drought (having higher undergroundwater level) absorptions all have high production, the order is shallow wet irrigation > full wet irrigation> drought irrigations, which shows that the rice growth process needs great capacity water, but there is very big space of exaltation on the water exploitation efficiency, 7: During the growth of paddy, the elements amount in full wet irrigation are the highest, than is shallow wet irrigation, the lowest are drought irrigation and non-full irrigation. Consider with the product and the element content, shallow wet irrigation has higher efficiency, and drain less, cansatisfy with the need of continuance development...