Experimental Research on Variation Feature of Three Kinds of Nitrogen from Paddy Field in Qingtongxia Irrigation Area
With strict controlling of point source pollution,how to understand and control non-point source pollution scientifically and effectively has become the important pressing research.Agricultural non-point source pollution due to wide application of fertilizers and pesticides is becoming the major cause of the environment deterioration.It has been researched in 1980s in our country,and now it becomes a research hotpot.An experiment was done to asses the loss of nitrogen in paddy field in Qingtongxia irrigation area,Ningxia.Based on this experiment,this paper tried to find out TN,NH+4-N and NO-3-N transportation and transformation law in paddy field,in soil profile and in drainage ditch.The result showed that:(1)In paddy field,the concentration of TN in discharging water was higher than that in introducing water.TN in accumulating water was lower than that in discharging and introducing water from May to June,the case was the contrary from July to August.The concentration of NH+4-N in introducing water was lower than that in accumulating and discharging water.From May to July,the concentration of NO-3-N was in the order of discharging water ＞introducing water ＞accumulating water,and which had no obvious characteristics in August.(2)Three kinds of nitrogen were in the highest content at the range of 0～20 cm soil layer,and tended to decrease with depth.The content of TN after irrigation was higher than that during irrigation periods and the case of NH+4-N and NO-3-N was just on the opposite.(3)The vegetation in drainage ditch had degradative effeet on three kinds of nitrogen,and the rate was in the order of NH+4-N＞TN＞NO-3-N,which also had a close link with vegetation coverage,the length of ditches,water flow and other factors.
Qingtongxia irrigation areapaddy fieldthree kinds of nitrogenvariation feature
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