Abstract: 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.

Key words: Soil water, Root development, Nutrient transfer, Nitrate, Ammonium