黄土层中灌溉对尿素淋失特征的影响

Effect of Irrigation on Urea Leaching Characteristic in Loess Layer

通过灌溉施肥实验和N素淋失通量法,研究黄土塬区和黄土台面阶地区超根层黄土中NH4-N和NO3-N的分布和运移规律,结果表明,在根层土壤贫N时,3m以下尿素N淋失率为13.2%～41.3%,在根层土壤富N时,淋失率为56.6%～83.5%,即黄土灌区在灌水定额较大时,仍然会产生强烈的N淋溶损失,因此,在黄土灌区科学施肥和节水灌溉对提高肥效和保护地区水质至关重要。

The effects of nitrogen fertilizer and irrigation on the distributions and movement rules of ammonium nitrogen and nitrate nitrogen in loess layer were investigated in field. The results showed that the content of ammonium nitrogen was steadier than nitrate nitrogen in 0~10 m layers, the smallest content was 3μg N/g, and the biggest content was 8 μg N/g, most determining results ranged from 5.5 μg N/g to 6.5 μg N/g. By using nitrogen leaching flux equation, we calculated that the urea nitrogen leaching rate under 3 m soil layer was 13.2%~41.3% when nitrogen in tillage layer was poor, and it was 56.6%~83.5% when nitrogen in tillage layer was rich, it is indicated that the nitrogen leaching loss also occurred when the irrigation amount was higher, so both scientific application of nitrogen fertilizer and control irrigation amount is important in loess irrigation areas in order to increase fertilizer effect and protect ground water quality.