A Study On The Change Regularity Of Nitrogen And Phosphorus Elements Of The Field Paddy And Under Different Irrigation

Unreasonable irrigation and drainage measures caused a huge loss of pesticides and chemical fertilizers, and it led to water pollution around the paddy fields,and it will also affected the growth and development of the rice and production eventually. Therefore, taking appropriate irrigation methods has an important significance on the agricultural production of rice according to local conditions.It is carried out field experiment in Qinjia of Suihua in Heilongjiang province . The experiment is carried out by regular irrigation method,flooding irrigation method , controlled irrigation method , controlled and non-drainage irrigation method based on local irrigation method.It is researched on the changing characteristics of ammonia nitrogen, nitrate nitrogen ,the total phosphorus of surface water and the leakage water department that is 60cm below to the surface under these four fields irrigation. At the same time, the growth and development indicators of the reproductive period of rice have been observed (including leaf age, leaf area index, tiller number, plant height, root status), and the rice production indicators and the lodging resistance of rice are measured.The result is showed:The nitrogen and phosphorus elements of surface water and underground water are rise in visiblily at first after fertilization,Then, they are decreased and they are stabilized gradually by the plants absorbing and leaching. The nitrogen and phosphorus elements underground water is not only too small, relatively stable, but also is the lowest value under controlled irrigation.But flooding irrigation method is opposite. Nitrate nitrogen is higher under regular irrigation.Ammonia nitrogen and the total phosphorus content values are lower under regular irrigation.Therefore, from the view of reducing the element of non-point source pollution in paddy field , the controlled irrigation measures is an best and effective way to reduce nitrogen and phosphorus pollution of water after fertilization. The degree of non-point source pollution is greatest under flooding irrigation method.From the view of rice growth and development, the root growth and tillering of rice is best under controlled irrigation,the regular irrigation method is second. The indicators of leaf age, leaf area index and height indicators is highest under regular irrigation, the controlled irrigation is second,But all of growth and development indicators are the lowest under flooding irrigation method.Therefore, using more suitable methods of irrigation is the best way to promote rice growth and development, whereas the flooding methods of irrigation has hindered the growth of rice.From the economic view,it is the minimum irrigation water and maximum theoretical yield of rice and the best effects of lodging under the controlled irrigation method.But the flooding rrigation method is oppositeTherefore,it is the controlled irrigation that is best way of reducing agricultural non-point source pollution and ensuring rice growth and development and obtaining best economic.