水肥一体化滴灌滴头堵塞机理及防堵策略研究

Fertilizers injected into a drip irrigation system is considered as the most secure and reliable irrigation method for fertilization due to its precision and controllability. It can avoid the traditional high consumption agricultural production way, ease the crisis of water resource and promote crop growth. However, the water contains a large amount of particles, nutrient salts,organics, micro-organisms and other substances, which makes the emitter clogging mechanism become more complex and also significantly increases the risk of emitter clogging.That is a major drawback of drip irrigation systems that must be addressed to improve their efficiency and durability. To better understand the causes and process of the emitter clogging with fertigation at different types and levels through in-field and lab experiments coupled with a numerical approach. In addition, spectrum characterization techniques (ATR-FTIR, XPS and XAFS) are also combined to determine the interaction mechanisms and microstructures. The project is expected to reveal main issues from both the macro- and micro- perspectives: the correlative mechanisms among the agglomeration, sorption, and precipitation reactions at sand paticles/salts interfaces are closely related with the distribution, migration, transformation, accumulation, and clogging in drip irrigation. The prospective findings in this project will have a meaningful theoretical reference value for predicting the clogging of drip irrigation and controlling mode after considering emitter clogging clear. Furthermore, the results obtained from this study provide a basis for formulating reasonable fertigation management strategies.

水肥一体化滴灌是作物水分和养分定量供给，并维持土壤适宜水肥和养分含量的有效方法，该技术的精量性是其重要特点，可改善农业用水方式、提高农业水利用效率。灌溉水中含有的大量矿物微粒、盐分离子和细小固体悬浮颗粒，易造成滴头堵塞，故水肥一体化滴灌可能存在加速滴头堵塞的风险。为提高水肥一体化滴灌系统的安全运行能力，本项目针对目前施肥滴灌滴头堵塞普遍存在的问题，采用宏观统计试验、微观光谱表征和相关水动力学模型模拟相结合的方式，从宏观和微观两个方面揭示多相复杂水源滴灌，滴头堵塞发生规律、堵塞物质组分及微观结构、堵塞物形成的絮凝/吸附/沉淀动态反应机理，对于评估和预测滴灌施肥系统堵塞和防治堵塞发生具有重要的理论价值和指导意义，对提高滴灌施肥的运行管理技术，协同提升水肥利用效率具有重要的借鉴意义和应用前景。

灌溉水然含有化学离子、悬浮泥沙和微生物等，滴头流道为狭长而细小的迷宫结构，因此，特别容易在固体颗粒聚集黏附、化学垢、微生物滋生等共同作用下，逐渐堵塞滴头流道，即滴头发生堵塞，影响滴灌系统的正常运行。水肥一体化滴灌技术是未来农业应用前景非常大的技术，肥料的加入会增加水中离子含量，改变水的力学和化学性质进而会改变悬浮颗粒、化学离子和微生物的相互作用，加速或者延缓悬浮颗粒的聚集、沉降或者黏附等，从而提高了滴头堵塞风险。为此，本项目开展了肥料类型、肥液浓度及温度等对滴头堵塞的影响研究，分析了滴头堵塞物质微观表面性质表征、悬浮颗粒吸附沉淀机理，并提出应对水肥一体化滴灌滴头堵塞的控制方法。通过研究发现，肥料类型和肥液浓度是影响滴头堵塞的主要因素，当肥液质量浓度超多3%时，无论是尿素、硫酸钾、磷酸二氢钾，或者复合肥，施肥后滴头流量下降速度显著高于未施肥的浑水试验滴头，施肥具有加速滴头堵塞的风险。由于灌溉水中增加肥料后，降低了水的pH，提高了水的电导率，增强了悬浮颗粒的絮凝沉降机会，易使滴头发生堵塞。本项目分析了肥液类型、浓度，不同肥料配比对水的pH、电导率的影响，并建立了通过电导率和pH预测肥液浓度和配比的经验模型。.毛管冲洗是缓解滴头堵塞的重要措施。本项目研究发现，当灌溉一定时间后，适当冲洗毛管（5分钟），可以大幅度恢复滴头流量，显著提高滴头的有效灌水次数。通过试验，初步推荐首次宜在灌水9次后冲洗，后续冲洗间隔为5-7次。.本项目的研究成果为今后继续研究提供了参考依据和借鉴，初步确定的肥料类型和浓度对滴头堵塞的影响规律，确定的首次冲洗时间，合理的冲洗间隔，对于滴灌系统抗堵塞设计和管理，具有技术参考价值。