The Combined Effect of Temperature and Pressure on Emitter Clogging in Integrated Drip Fertigation System

【Background and objective】 Water-fertilizer integrated drip irrigation has advantages over traditional methods, including even fertilization, saving water and fertilizer, and precise control. However, emitter clogging is a problem limiting its widespread use. While emitter clogging is affected by various factors, the role of irrigation water temperature is poorly understood. This paper is to investigate the combined impact of temperature and working pressure on emitter blockage in a water-fertilizer integrated irrigation system. 【Method】 We used the plain channel emitter; the short-cycle intermittent irrigation clogging tests were conducted under temperature ranging from 15 to 30 ℃, and working pressures at 50 kPa (low) an 100 kPa (normal). Ammonium phosphates were used as the fertilizer and tap water as the irrigation water. Average water flow in the emitter was monitored; at the end of the experiment, the geometrical structure and composition of the clogging materials were analyzed using SEM; the blocking position in the emitter was also measured. 【Result】 Ammonium phosphate had a significant effect on clogging; irrigation reduced the average relative flow in the emitter by 15.03%~34.02%. Temperature rise increased the average relative flow, and the increase under the low pressure was greater than under the normal pressure. Irrigation increased the average relative flow by 18.55% under low pressure and 14.88% under normal pressure. The temperature did not affect the main components of the clogging material. The mechanisms underlying the blockage involve physical blockage by flocculation and replacement of ions in formation of the flocculation. However, increasing temperature weakened the flocculation and reduced surficial complexity of the blockage materials. In the emitter, the blockage was mainly located at the transition zone, the channel head, and the tail of the channel, which accounted for 29.75%, 22.31%, and 22.31% of the blockage, respectively. Changing temperature did not affect the blockage location. Therefore, it is recommended to optimize the structure of the transition zone, the channel head, and the tail of the channel to alleviate the blockage. 【Conclusion】 Increasing temperature can reduce flocculation thereby alleviating emitter blockage to some extent, regardless of working pressure.