交替隔沟灌溉和施氮对玉米根区水氮迁移的影响

Effects of Alternative Furrow Irrigation on Transport of Water and Nitrogen in Maize Root Zone

【目的】研究交替隔沟灌溉条件下作物根区土壤水氮迁移和累积。【方法】利用小区试验,对供试玉米采取不同的水分和氮素处理,测定交替隔沟灌溉条件下玉米根区土壤硝态氮、铵态氮和水分的变化。【结果】施氮后沟中硝态氮含量增长很快,大多集中在地表下0～30cm处。随着时间的推移,上层土壤水分携带氮素养分下渗,造成下层土壤硝态氮含量的上升。收获时低水高氮处理的整个剖面上硝态氮的累积量最大,是高水高氮处理的1.2倍,低水低氮处理的是高水低氮的1.27倍。施氮后表层0～30cm土壤铵态氮含量和累积量达到高峰,30cm以下变化不明显。收获时各处理的铵态氮在剖面上的分布和累积基本相同。高水处理的土壤水分累积量明显大于低水处理,氮素水平的高低对土壤水分的累积影响不大。【结论】施氮量和灌水量是影响土壤硝态氮、铵态氮和土壤水分分布和累积的最主要因素。高水处理造成根区硝态氮淋失,降低了氮肥的利用。施氮量与硝态氮在根区剖面上的累积呈正相关。与硝态氮含量相比,铵态氮含量较低并且变化不大。最佳的水氮耦合形式为低水高氮(施氮量240kgN·ha-1,灌水量1485.71m3·ha-1)。

[ Objective ] Effects of alternative furrow irrigation on transport and accumulation of water and nitrogen in maize root zone were investigated. [Method] In this plot experiment, maize was treated with different amounts of water and nitrogen. The water and nitrogen treatments included were high level and low level treatments. The mode of irrigation was alternative furrow irrigation. [Result] NO3^--N contents increased quickly after fertilization, most of which was concentrated in the sub-surface of 0-30 cm. With the prolonging time, the upper soil water took the nitrogen contents down while bringing the NO3^--N contents of subsoil raised. The maximal accumulated NO36--N of low water and high nitrogen gained at harvest time in the whole profile was 1.2 times of that of high water and high nitrogen. The accumulation of NO3^--N of low water and low nitrogen was 1.27 times of that of low nitrogen and high water. After fertilizing, the NH4^＋-N contents in the soil of 0-30 cm reached a peak, though the contents basically did not change in the soil of 30 cm below. The accumulation and distribution of NH4^＋-N of every treatment were basically the same at harvest time. The level of water markedly affected the accumulation and distribution of soil water content. The accumulation of soil water content of high water was greatly larger than that of low water, which was not obviously affected by the level of nitrogen. [Conclusion] The distribution and accumulation ofNO3^--N, NH4^＋-N and soil moisture were all affected by the amount of nitrogen and irrigation. The treatment of high water reduced the accumulation of NO3^--N in root zone, as well as led to leaching and reduced nitrogen fertilizer use efficiency. The treatment of low water kept high content of NO3^--N in root zone, assisted with the absorption of the crops and raised the use efficiency of water and nitrogen. A positive correlation existed in amount of nitrogen application and NO3^--N accumulation in root zone. Compared with NO3^--N, the content of NH4^＋-N was lower and basically did not change. The best combination was the treatment of low water and high nitrogen （nitrogen rate was 240 kgN·ha^-1 and irrigation water quota was 1485.71 m^3·ha^-1）.