施肥滴灌加速滴头堵塞风险与诱发机制研究
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国家重点研发计划项目(2016YFC0400202)和国家自然科学基金项目(51679205)


Risk and Inducing Mechanism of Acceleration Emitter Clogging with Fertigation through Drip Irrigation Systems
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    摘要:

    以2种内镶片式迷宫流道滴头为研究对象,采用数学分析方法、扫描电镜/能谱分析技术(SEM—EDS)和X射线衍射技术(XRD)对不同水溶性肥料滴灌后滴头流量、堵塞物表面微形貌及其化学组分进行多角度分析,研究肥料特性和流道结构对滴头堵塞过程的影响效应。结果表明:肥料特性是决定堵塞类型和诱发风险的重要因素(P<0.01),流道结构对堵塞的影响需双重考虑结构尺寸及结构类型;当施肥质量分数小于等于0.5%时,施肥加速滴头堵塞的效果较小且与肥料类型关系不大,当施肥质量分数在0.5%~2.0%之间时,各肥料滴灌适用性由大到小依次为:磷肥、尿素、钾肥、复合肥,当施肥质量分数在2.0%~3.0%之间时,尿素滴灌滴头流量降幅为10.26%,显著高于施加磷肥(7.85%)、钾肥(4.07%)和复合肥(2.74%);施加尿素滴灌诱发滴头堵塞主要物质的形成机理为分子态尿素析出物与水中悬浮颗粒物形成团聚体在较差流体的运动粘度下造成的物理堵塞,磷肥主要为吸附作用加速肥料杂质团聚沉淀的物理、化学堵塞,硫酸钾施肥滴灌主要为离子交换形成的钙、镁沉淀导致流道壁面糙度升高、过水断面减小的化学堵塞过程,复合肥诱发滴头堵塞风险最低。施肥滴灌存在诱发或者加速滴头堵塞的风险,但不同肥料诱发滴头堵塞主要物质的形成机理不同,加速堵塞的风险也不同,故对于不同的肥料类型宜采用不同的抗堵塞管理策略。

    Abstract:

    The inducing mechanism of emitters clogging with fertigation was explored. A laboratory experiment was conducted to investigate the influence of three factors (fertilizer types, fertilizer concentration and flow path structure) on anti-clogging performance of drip emitters. The intermittent drip irrigation experiment was studied by using two flow path types of non-pressure compensating emitters (arc-shaped saw-tooth and cup-shaped saw-tooth), four levels of fertilization concentration (0.5%, 1.0%, 2.0% and 3.0%) and four types of fertilizer (urea, calcium superphosphate, potassium sulfate and water soluble compound fertilizer) and the system was allowed to run for 20 h. The mathematical analysis methods in combination with field scanning electron microscope (FESM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) technology were then used to quantitatively and qualitatively analyze the variations of the emitter’s average relative flow rate, surface topographical characteristics and components of the clogging materials internal emitters. Results showed that fertilizer characteristic was an important factor in deciding the emitter clogging type and degree (P<0.01), and the influence of the two flow path structures on the accelerating effect of emitter clogging performance needed to consider the path structural size and style. The accelerating effect of fertilizer application on emitter was not obvious when the concentration of fertilizer solution was less than 0.5%. When the concentration was increased to 0.5%~2.0%, there were obvious changes in the quantities of outflow discharge occurred in phosphate-fertigation, which made it clog easily, followed with urea-fertigation, the applicability of potassium-fertigation and compoundfertigation was better than that of the former. When the concentration was risen to 2.0%~3.0% or higher, the clogging degree was so serious with ureafertigation, the flow rate was decreased by 1026%, which was significantly higher than those of phosphate-fertigation (7.85%), potassium-fertigation (4.07%) and compound-fertigation (2.74%). Fertilization can promote the clogging of the emitters. These fertilizer types had different water quality, hence resulting into different emitter clogging risk and inducing mechanism. Emitters clogging with urea fertigation were caused by the role of aggregation and adhesion with both crystallization of the molecular urea state and suspended particles in the water. The adsorption function that particulate impurities to phosphorus promoted flocculation while precipitation among solid particles was as a result of inducing mechanism of emitter clogging with phosphate fertigation. The main inducing mechanism for emitter clogging with potassium-fertigation was chemical precipitation because of the ion-exchange action, while emitter clogging with compound-fertigation had the lowest risk. Therefore, fertigation with different fertilizer types should adopt different emitter clogging controlling management strategy.

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刘璐,牛文全,武志广,官雅辉,李元.施肥滴灌加速滴头堵塞风险与诱发机制研究[J].农业机械学报,2017,48(1):228-236.

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  • 收稿日期:2016-09-04
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  • 在线发布日期: 2017-01-10
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