表施尿素下引黄畦灌水流中氮素迁移转化规律试验研究

An Experimental Study of the Transportation and Transformation of Nitrogen in Border Irrigation with Yellow River Water under Surface Urea

为了研究引黄灌溉条件下氮素在地表水流中的特点,促进表施肥料下田间灌溉系统设计和管理的改进,基于引黄畦灌撒施和液施尿素试验资料,分析了地表水流中尿素沿畦长的迁移转化过程,水流水力、水质的影响,以及氮素浓度的时空变异特征。结果表明,水流中氮素主要以有机氮的形式存在,尿素的水解需要一个过程;悬浮颗粒物不是引起不同氮素沿程变化的主要原因。撒施在流速等作用下,氮素存在明显的畦首流失,畦尾累积,且总氮、有机氮、氨氮和硝氮与距离的相关系数都大于0.8,为高度相关。施肥方式对地表水流中氮素分布有显著的影响,液施较撒施可以提高地表水流中氮素时空分布的均匀性,总氮在撒施30 min时的变异系数比开始大0.38。不同氮素的性质不同,在迁移转化过程中不完全同步。

The aim of this work is to study the characteristics of nitrogen in the surface water under Yellow River irrigation and promote the improvement of design and management of surface fertigation practice. Based on the experimental data from border irrigation surface water with the Yellow River water under scattering and fertigating urea, this paper discusses the transportation and transformation of urea along the border lengthwise in surface water, the effects of surface hydraulic power and water quality, and the spatial and temporal distribution of the concentration of nitrogen. The results show that nitrogen mainly exists in the form of organic nitrogen, hydrolysis of urea needs a process. The sediment content is not the main reason of the change of nitrogen concentration along the border lengthwise. Under the influence of flow velocity, it is obvious of the washing in the border＇s front end and the accumulation in the back end of nitrogen in scattering, and the coefficient of correlation of concentrations of total nitrogen, organic nitrogen, ammonium and nitrate along the border lengthwise in surface water and distance are more than 0.8, which is high correlation. The fertilizing methods obviously have an effect on the distribution of nitrogen in surface water. The spatial distribution uniformity of nitrogen in surface water can be improved under fertigation. Variation coefficient of total nitrogen within 30 minutes is more than 0.38 than it was predicted. Different kinds of nitrogen have different natures, which leads to no synchronization in the process of transportation and transformation.