宁夏银南灌区稻田控制排水条件下氮素淋失的研究

Experiment on the nitrogen leaching in the drainage condition of rice field in Ningxia Yinnan irrigation region

为探讨不同排水条件下稻田中氮素的迁移、转化规律,通过大田试验,对宁夏银南灌区稻田土壤中氮素的淋失情况进行了研究。结果表明,排水量越大,NH4+-N下移深度越大;在下渗水流的驱动下,NO3--N的下移深度明显大于NH4+-N;不同排水处理中,土壤剖面NH4+-N浓度呈现随深度增加逐渐降低的趋势,NO3--N浓度在地面以下100 cm内随深度增加逐渐升高,超过100 cm之后逐渐降低;每次施肥后,不同处理的排水中NO3--N和NH4+-N浓度均表现出短期内迅速上升,以后又逐渐下降的趋势;氮素的淋失主要发生在拔节期以前,在此期间,应加强水肥管理,以减少氮素淋失。

A nitrogen transportation experiment was conducted in Yinnan irrigation district. Based on this experiment,this paper tried to find out the nitrogen transportation and tansformation law in rice field under different dranige treatment, The results show that the depth of NH4^＋ -N transferring increases with the increase of drainage volume ;Driven by the leached water flow,NO3^＋ -Nand NH4^＋ -N can be tranfered into the ground at a certain depth ,but NO3^＋ -N is deeper than NH4^＋ -N ;The concentration of NH4^＋ -N in different treatment soil profile tends to decrease with the depth;The concentration of NO3^＋ -N tends to increase with the depth at rangea of 100 cm,then decreased gradually. Nitrogen leaching occurs maily before June 9 in the same year,during which,the management of water and fertilizing should be enforced in order to reduce nitrogen loss.