Emitter clogging risk might be enhanced by the specific fertigation practice when applying saline water. Two stages of on-site drip irrigation experiments applying saline water were conducted to investigate the effects of the phosphorus (P) fertigation and combined P and nitrogen (N) fertigation and the water salinity on emitter clogging when using a plain channel emitter and a labyrinth emitter. During stage one, the water-soluble phosphate fertilizers monoammonium phosphate (MAP), diammonium phosphate (DAP), and urea phosphate (UP) were tested in comparison with a control treatment without fertigation (CK). During stage two, four combined P and N fertigation practices were tested by mixing one phosphate fertilizer (MAP or DAP) with one N fertilizer (urea (U) or ammonium sulphate (AS)). Four levels of water electrical conductivity measuring about 0.5 (groundwater, G), 2 (S2), 4 (S4), and 6 (S6) dS m−1 were tested at both experimental stages. The discharge rates of the emitters were measured following every other two fertigation events during stage one and following each fertigation event for stage two. At the end of the experiments, several representative emitters were sampled to measure the dry weight and the chemical constituents of the clogging substances in the emitters. The results demonstrated that the P fertigation with a weak or a slightly stronger acidic fertilizer such as MAP or UP reduced the emitter clogging effectively during groundwater application. For saline water application, the emitter clogging clearly increased with the water electrical conductivity. Phosphorus-coupled nitrogen fertigation accelerated the precipitation of phosphate sediments greatly when either groundwater or saline water was applied. In fact, the precipitation of phosphate sediments exceeded 80% of the dry weight in the emitters under saline water irrigation. Rapid development of emitter clogging occurred for both types of emitters when saline water with electrical conductivity higher than 4 dS m−1 was applied under phosphorus-coupled nitrogen fertigation. The phosphorus-coupled nitrogen drip fertigation should be applied with cautious when applying saline water with electrical conductivity higher than 4 dS m−1. Fertigating with nitrogen fertilizers along with acid phosphate fertilizers together is a promising way to alleviate the emitter clogging caused by the ion components in saline water.

中文翻译：

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磷耦合施氮肥对盐水滴灌器堵塞的影响

使用盐水时，特定的施肥实践可能会增加发射器堵塞的风险。进行了两个阶段应用盐水的现场滴灌实验，研究了磷（P）灌溉施肥和磷氮（N）联合灌溉以及水盐度对使用普通渠道滴头和迷宫滴头时滴头堵塞的影响发射器。在第一阶段，将水溶性磷肥磷酸一铵 (MAP)、磷酸二铵 (DAP) 和磷酸尿素 (UP) 与不施肥 (CK) 的对照处理进行比较。在第二阶段，通过将一种磷肥（MAP 或 DAP）与一种氮肥（尿素 (U) 或硫酸铵 (AS)）混合，测试了四种结合磷肥和氮肥的做法。在两个实验阶段测试了四个级别的水电导率，测量值约为 0.5（地下水，G）、2（S2）、4（S4）和 6（S6）dS m-1。在第一阶段期间每隔两次施肥事件之后以及在第二阶段的每个施肥事件之后测量排放器的排放率。在实验结束时，对几个有代表性的排放器进行采样，以测量排放器中堵塞物质的干重和化学成分。结果表明，使用弱酸性或稍强酸性肥料（如 MAP 或 UP）的磷肥可有效减少地下水施用过程中的排放器堵塞。对于盐水应用，发射器堵塞随着水的电导率明显增加。施用地下水或盐水时，磷耦合氮肥可大大加速磷酸盐沉积物的沉淀。事实上，在盐水灌溉下，磷酸盐沉积物的沉淀超过排放源干重的80%。当在磷耦合氮肥灌溉下施用电导率高于 4 dS m-1 的盐水时，两种类型的灌水器都会发生灌水器堵塞的快速发展。施用电导率高于4 dS m-1的盐水时，应慎用磷偶联氮滴灌施肥。将氮肥与酸性磷肥一起施肥是缓解盐水中离子成分造成的发射器堵塞的有希望的方法。