根系的吸收作用及土壤水分对硝态氮、铵态氮分布的影响

 研究了玉米根系的吸收作用和土壤水分对耕层土壤硝态氮迁移及分布的影响。结果表明，根系发育状况及水分供应明显影响硝态氮的迁移及分布。根系自然生长和灌水处理，距主茎不同距离的各位点硝态氮浓度差异小；而限制根系生长和不灌水处理，则差异较大。距主茎0～10 cm范围的耕层土壤中硝态氮含量的变化趋势是由远到近逐渐降低。这种变化趋势与耕层土壤中根系吸收面积的变化趋势相反。限制根系生长时，各位点土壤硝态氮浓度与土壤水分有相当一致的变化规律，说明随着植物吸水硝态氮作为溶质向根表迁移。与硝态氮不同，铵态氮的迁移和分布不受根系发育状况及水分供应的影响。

Effects of Root Uptake Function and Soil Water on NO3- -N and NH4+-N Distribution

The effects of root uptake and soil water on transfer and distribution of NO3 -N in arable soil were studied by using - summer maize (Zea mays L. var. Shandan9) as experimental crop. Results showed that root development and water supply had an obvious effect on the transfer and distribution of NO3 -N. Under a natural growing conditions with irrigation , the difference of - NO3 -N concentrations at different distances from the stem was smaller, but obvious difference of NO3 -N concentration was - - observed under the conditions of a limited root growth space without irrigation. Whether restricting root growth space or not, the content of soil NO3 -N decreased gradually from 10 cm to 0 cm from the stem, being opposite to the root absorbing area in soils. - When root growth space was limited, changes of NO3 -N concentration at different distances from the stem were similar to that of - soil water content. Results showed that NO3 -N could be transferred as solute to plant root systems with water uptake by plants. - However, the transfer and distribution of NH4 -N were not influenced by root growth and soil water supply, being different to + NO3 -N. -