肥料类型及浓度对水肥一体化浑水滴灌滴头输沙能力的影响

Effect of fertilizer type and concentration on sediment transport capacity of dripper in drip fertigation with muddy water

为研究浑水水肥一体化灌溉过程中,不同肥料对滴头输沙能力的影响,合理配置滴灌系统首部的过滤设备和设施,降低过滤设施的成本,提高滴灌系统工作效率,选取了常用的3种肥料(尿素、硫酸钾和水溶性复合肥)及其3种肥料质量分数(1%、2%和3%),在含沙量为1 g/L的浑水条件下进行间歇灌水堵塞试验,分析了滴头累积泥沙输出量、出流含沙量和泥沙输出率。结果表明:浑水施肥可以增强滴头的输沙能力,肥料类型和浓度不同,对滴头输沙能力的影响也不同。滴头输沙能力随着尿素浓度的增大而增大,当尿素质量分数为3%时,滴头输沙能力比未施肥处理增加了11%(P<0.05)。滴头输沙能力随硫酸钾和复合肥浓度的增大而减小,当硫酸钾质量分数为1%时,滴头输沙能力大于未施肥处理,增大了25%;当复合肥质量分数>2%时,滴头输沙能力小于未施肥处理。标准化的累积泥沙输出量与标准化的累积灌水量的拟合直线斜率也可作为滴头输沙能力的判断依据,肥料质量浓度是影响滴头输沙能力的重要因素,应根据不同的肥料类型,确定适宜的施肥浓度。研究结果对确定滴头防堵塞策略提供一定的参考。

Emitter clogging has been an important factor restricting the application of drip irrigation system.In order to improve the anti-clogging ability of the dripper,the front part of the drip irrigation system needs to be equipped with multi-stage filtration equipment or facilities.This study investigated the effect of different fertilizers on the sediment transport capacity during the integrated irrigation of muddy water with fertilizer in order to make rational allocation of filtration equipment and facilities of the first drip irrigation system,to reduce the cost of filtration facilities and to improve the efficiency of drip irrigation system.A total of3kinds of fertilizers(urea,potassium sulfate and water-soluble compound fertilizer)as well as3different concentrations(1%,2%and3%)were chosen to carry out intermittent irrigation clogging test in muddy water with the sediment concentration of1g/L.The accumulated sediment,discharge sediment of drippers and rate of discharge sediment for drippers were analyzed.Tap water was applied as the test water.Experimental sediment was taken from river flood beach silts along Weihe River in Shaanxi Yangling.The working pressure of this test was set to70kPa based on the preliminary experiment results.In order to increase irrigation times of this experiment,the test stopped when the average relative flow rate was below70%.The test also stopped after20times of irrigation even though the relative flow rate was still above70%.The results showed that the application of muddy water could enhance the sediment transport capacity of dripper.Different types and concentrations of fertilizer had different effects on the sediment transport capacity of dripper.Sediment transport capacity of dripper increased with rising urea concentrations.Compared with no fertilization treatment,when the urea concentration was3%,the capacity value increased by11%(P<0.05).Sediment transport capacity of dripper decreased with the rising concentrations of potassium sulfate and compound fertilizer.As the concentration of potassium sulfate was1%,the sediment transport capacity of dripper was significantly higher than that without fertilization(P<0.05)but as the concentration of compound fertilizer was above2%,sediment transport capacity of dripper was lower than no fertilizer treatment.The slope of the fitted straight line between the standardized accumulated sediment and the standardized accumulated irrigation amount could be used as the evaluation index for sediment transport capacity of dripper.The smaller the slope indicated that as the irrigation volume increased,the output of sediment of the dripper was lower,and the sediment transport capacity of dripper was also lower.The dripper was more likely to be clogged.Discharge sediment for drippers increased with the increasing frequency of irrigation.At the later stage of irrigation,its growth slowed down.Fertilization increased the maximum value of discharge sediment for drippers.With the increase of irrigation times,the rate of discharge sediment for drippers gradually decreased.After applying urea,rate of discharge sediment for drippers decreased with increasing irrigation times.After applying urea in the muddy water,the viscosity coefficient of irrigation water decreased with the increase of fertilizer concentration,while it increased with the rising concentration of compound fertilizer.After applying potassium sulfate in muddy water,the coefficient of irrigation water viscosity was higher than that without fertilization.The fertilizer concentration was an important factor that affected drip sediment output capacity.Appropriate fertilization concentration should be determined according to different types of fertilizers.The results provide valuable information for determining the anti-clogging strategy of dripper and improving the sediment transport capacity of dripper to guide integrated drip irrigation of water and fertilizer with high sediment concentration in the Yellow River irrigated area.