茭白田坑面水和渗漏水中氮素变化动态研究

Distribution and fate of nitrogen species in simulated water bamboo fields

茭白是黄浦江上游地区广泛种植的一种水田蔬菜。通过测坑定位试验,研究了茭白田坑面水和渗漏水中氮素变化动态和流失规律。结果表明,各处理茭白田坑面水中氮素形态以NH4+-N为主,施肥后1～3d,其占TN比例可达90%以上;渗漏水中氮素形态主要以NO3--N为主,施肥后呈现先上升后下降的趋势。通过增施有机肥、减少20%的无机氮肥用量可使坑面水TN减少20.74%,渗漏水中NO3--N减少16.10%,减少了氮素流失,且对茭白产量没有显著影响。

Water bamboo is a paddy vegetable planted widely in the upstream areas of Huangpu River. The dynamic distribution and fate of nitrogen species in the surface-water and leaking-water of simulated water bamboo fields were evaluated by the leaching-pond orientation experiments. Three fertilization programs of different combinations of urea and an organic fertilizer were employed to provide 1 500 kg N/hm^2 to each of 9 small fields （three groups of three replicates） in 3 events （base, first and second fertilizations） during March-July in 2008. The results show that NH＋-N was the dominant nitrogen form in the surface-water and that the NH＋-N/TN ratio went up to 〉90% in 1 to 3 days after fertilization. NO3^- -N was the main form of nitrogen in the leaking-water; after fertilization, its concentration increased initially and then decreased. Replacing a portion of urea with an organic fertilizer to supply 20% of the desired nitrogen application reduced TN loss in the surface-water by 20.74% and also reduced the NO3^--N concentration of the leaking-water by 16.10 % without causing a significant reduction in water bamboo yield.