冬小麦田间根层中氮素迁移转化规律研究

A Study on Transformation and Transportation of Nitrogen in the Root Zone of Winter Wheat in the Fields

在冬小麦生长期田间试验的基础上，建立了土壤──作物系统中水分运动及不同形态氮素迁移转化的数学模型，该模型考虑了有机氮的矿化、铵氮的硝化与挥发、硝态氮的反硝化以及土壤吸附、作物吸收等多种影响因素，利用溶质扩散──对流方程模拟了冬小麦生长期田间水分、铵氮、硝态氮含量及其分布的变化。模拟模型计算结果与田间试验结果比较说明，数学模型能较好地模拟田间的实际情况。模型计算结果表明，在不同灌水定额情况下，６０ｍｍ／次的灌水量就能基本满足作物生长的需要，而且几乎不造成深层渗漏。增大灌水定额，作物吸收水量的增加十分有限，却可能导致大量水的深层渗漏损失，溶解在土壤水中的硝态氮亦随土壤水往深层移动，作物吸收的氮量有所减少，并且随土壤水的下渗，硝态氮的深层渗漏损失显著增加。

On the basis of long-term field experiment on winter wheat, the mathematical model of water and different kinds of nitrogen in the soil-plant system is set up. This model involves the mineralization of organic N, nitrification and volatilization of ammonium N,denitrification of nitrate nitrogen, absorption of soil and uptake of plant and so on. The distribution and changes of water, ammonium N and nitrate nitrogen in the field during winter wheat growing season are simulated with solute diffusion-convection equation. Comparation of experiment data with calculation results indicates that under the condition of different irrigation quota, the application amount by 60 mm of water each time can basically satisfy the needs for plant growth and cause little loss by deep percolation. However, increase of irrigation quota, can result in more loss by deep percolation while the increase of plant uptake is rather limited. Because of the downward movement of dissolving nitrogen into the deep layer along with soil water, nitrogen uptake by plant decreases whereas the loss of nitrate nitrogen by deep percolation increases remarkably.