Purpose

The intensive cultivation of turfgrass requires a high quantity of water and fertilizer. The fertilizers can leach and reach groundwater or be transported by run-off to water surface. It is necessary to improve irrigation and fertilization techniques to guarantee water and fertilizer optimal use and avoid contamination. The objectives were to analyze water flow and nitrate transport using the HYDRUS-1D and explore the effect of organic matter and hydrogel on the nitrate leaching.

Materials and methods

The experimental site was divided into 4 plots, each with an approximate area of 40 m² and a volume of 10 m³. The substrate is composed of sand, which is superimposed on a gravel layer where drainage pipes are installed to collect the leachates. The plots were constructed with different amendments in order to evaluate their influence on water flow and contaminant transport. The plot 1 contains organic matter (OM) and hydrogel (HG). The plot 2 contains OM. The plot 3 was constructed with only HG and the plot 4 with only sand.

Results and discussion

The results’ simulation indicated that the plot P1 retained water and, accordingly, retained the nitrate leached (2% of total applied nitrogen). The plot P4 drained a greater volume of water and nitrate leached (12% of total applied nitrogen). The greatest differences between the predicted and observed data occurred after 650 h, which appears to confirm the difficulty of modeling relatively long time periods. During this period, there may be changes in the hydraulic parameters that affect water flow. The simulations of nitrate transport indicated that the model partially represents the observed data. This may be due to aspects not considered in the model, such as moisture retention, piston flow, and preferential flow, which favor the leaching of more or less nitrates.

Conclusions

The use of hydrogel appears to be a good option for controlling leaching and, therefore, can be recommended, for example, in intensive crop fields or greenhouse crops.

中文翻译：

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有机物和水凝胶对草皮作物硝酸盐淋失的影响：使用HYDRUS进行的模拟研究

目的

集约化草坪草需要大量的水和肥料。这些肥料可以浸出并到达地下水，也可以通过径流运到水面。有必要改进灌溉和施肥技术，以确保水和肥料的最佳利用并避免污染。目的是使用HYDRUS-1D分析水流和硝酸盐的运输，并探讨有机物和水凝胶对硝酸盐浸出的影响。

材料和方法

将实验地点分为4个地块，每个地块的面积约为40 m ²，体积为10 m ³。基质由沙子组成，该沙子叠加在砾石层上，砾石层上安装了排水管以收集渗滤液。为了评估其对水流和污染物迁移的影响，对地块进行了不同的修改。小区1包含有机物（OM）和水凝胶（HG）。图2包含OM。地块3仅用HG建造，而地块4仅用沙子建造。

结果与讨论

结果模拟表明，样地P1保留了水，因此保留了沥滤出的硝酸盐（占总施氮量的2％）。地块P4排干了更多的水，并沥出了硝酸盐（占总施氮量的12％）。预测数据和观察到的数据之间最大的差异发生在650小时之后，这似乎证实了建模较长时间段的难度。在此期间，水力参数可能会发生变化，从而影响水流量。硝酸盐迁移的模拟表明该模型部分代表了观测数据。这可能是由于模型中未考虑的方面（例如水分保留，活塞流和优先流）所致，这些方面有利于或多或少的硝酸盐的浸出。

结论

水凝胶的使用似乎是控制浸出的好选择，因此，例如在集约化农田或温室作物中，建议使用水凝胶。