Effects of Drip Irrigation Frequency on Emitter Clogging using Saline Water for Processing Tomato Production

As an important parameter of drip irrigation using saline water, irrigation frequency not only affects crop growth by changing the soil moisture–salinity distribution, but also influences the anti‐clogging performance of the drip irrigation system by changing fouling growth inside emitters. Hence, a representative medium‐salt‐tolerant crop of processing tomatoes was selected as the research object. The effects of different drip irrigation frequencies (S1 (1‐day irrigation interval), S2 (2‐day irrigation interval) and S3 (4‐day irrigation interval)) on the clogging characteristics of emitters were analysed via a 2‐year drip irrigation experiment using saline water between 2013 and 2014. The results showed that the discharge ratio variation (Dra) and the Christiansen uniformity coefficient (CU) of the emitters decreased as the irrigation interval increased, while there was a negative linear correlation between Dra and the irrigation interval (R² > 0.79). The highest Dra and CU values of 80.9 and 78.0% were observed in high‐frequency irrigation (S1) after 2 years of planting. Moreover, clogging fouling inside the emitter accumulated gradually and exhibited a significant positive linear correlation with irrigation interval time (R² > 0.80). The chemical components of clogging fouling, which were calcium magnesium carbonates, quartz, silicates, and sodium chloride, were the same under different irrigation frequencies. The emitter clogging of drip irrigation systems using saline water for processing tomato production in the Hetao irrigation area presented a composite clogging (mainly chemical clogging associated with physical clogging). Considering previous research, a high frequency of once per day is recommended for drip irrigation using saline water. © 2019 John Wiley & Sons, Ltd.