太湖地区两种典型水稻土中氮、磷迁移转化的研究

研究了饱和状态下,铵态氮(NH4+-N)和速效磷(AP)在太湖地区两种主要水稻土-宜兴白土和常熟王庄黄泥土的原状土和扰动土中的迁移转化情况。结果表明,土壤的饱和导水率、粘粒含量对于铵态氮和速效磷的出流影响很大。在原状土土柱的出流中,白土滤液中NH4+-N、硝态氮(NO3--N)和速效磷浓度峰值出现的时间比黄泥土早,峰面比黄泥土窄,拖尾的时间比黄泥土短。速效磷在土壤中迁移及淋移都比NH4+-N弱,且黄泥土对磷的固定作用强于白土。在本试验NH4+-N的加入情况下,原状土土柱出流的NH4+-N如果进入地下水会造成地下水污染;NO3--N在黄泥土中的积累作用比白土强,出流的NO3--N含量较高;出流的NO2--N含量很低,不会造成地下水的NO2--N污染。土壤中的NH4+-N和速效磷可以通过大孔隙向下运移,并且随着深度的变化呈现降低的趋势。NO3--N在白土中的分布比较平缓。在扰动土的试验中,粘粒含量越低,饱和导水率越高,NO3--N的穿透曲线的峰值越高,峰面越窄。黄泥土的粘粒含量远高于白土,滞留作用较强,对NO3--N的穿透影响较大。本文结果可以为太湖地区地下水环境污染防治、农田水肥管理和防止水体富营养化提供依据。

Transference and Transformation of Nitrogen and Phosphorus in Two Typical Paddy Soils in Tai-Lake Region

Tow typical paddy soils(White soil in Yixing and Huangni soil in Wangzhuang,Changshu) were selected to study the transference and transformation of ammonium nitrogen(NH4+-N) and available phosphorus(AP) in saturated original and disturbed soil columns.The results showed that there was markedly influence of soil saturated hydraulic conductivity and soil clay content to NH4+-N and AP transference.During the experimentation of solute flow into original soil,the flow of NH4+-N,NO3——N and AP in White soil was faster than that in Huangni soil.The peak value area and durative time of their breakthrough curve in White soil were less than that in Huangni soil.It also showed that effect of transference and leaching of AP was worse than NH4+-N in soil.The AP fastness effect of Huangni soil was stronger than that of White soil.In this experimentation,concentration of NH4+-N filtering from original soil column exceeded the limit value types V(0.5 mg L-1) of groundwater which prescribed by quality standard for groundwater of China(GB /T14848-93).It would pollute groundwater through filtering,especially in some places with high groundwater table.Accumulation of NO3——N in Huangni soil was stronger than that in White soil.Therefore,concentration of NO3——N filtering from Huangni original soil column was higher.Concentration of NO2——N was very low in filtrate.NH4+-N and AP could transfer to bottom layer through macropore.Variation of NO3——N in White soil column was gentler.During the experimentation of disturbed soil,breakthrough curve of NO3——N showed that when clay content was lower and soil saturated hydraulic conductivity was higher,peak values of breakthrough curve was higher and peak area was narrower.Clay content in Huangni soil was higher than that in White soil.So resort effect of Huangni soil to NO3——N was stronger than that in White soil.These results could be provided to prevent groundwater against pollution and eutrophication,scientific farm fertilization and protection of environment in Tai-lake region.