Assessment of water quality ions in brackish water on drip irrigation system performance applied in saline areas

Abstract

Utilizing brackish water with drip irrigation technology, due to its precise water control alleviates the secondary soil salinization, and improves crop yield and quality, which offers sustainable agricultural development opportunities in saline areas. However, the complex characteristics of brackish water increase the risk of drip irrigation emitter clogging, which inhibit its promotion and adoption. It is necessary to find out the dominant water quality ions that lead to emitter clogging under multiple ion interactions when using brackish water under multiple ion coexistence conditions. Thus, the in-situ pilot research was conducted to study the emitter clogging mechanism using brackish water collected from 16 different salt-alkaline regions. A comprehensive evaluation with the consideration of 11 water quality ions on emitter clogging were conducted. Results showed that the degree of emitter clogging gradually increased in the first 40 days of irrigation, hereafter started an accelerated reduction until the days 64 of brackish water application. Spearman correlation and structural equation modelling were used to identify the main factors contribute to emitter clogging. And results indicated that calcium fouling (CF) and silica fouling (SF) were the major fouling minerals in the emitter flow channels. Ca2+, CO32-+HCO3-, pH, total hardness (TH), and zeta potential (ZP) were the key water characteristics leading to emitter clogging. These factors directly affected CF and SF, while also affecting the Mg2+, Mn2+, Cu2+, and other water quality factors which indirectly enhanced the CF and SF. Thereafter a few water quality control strategies were proposed based on emitter clogging and soil salinization mitigation. This study identified the key water quality ions that induce drip irrigation emitter clogging when using brackish water, provided solid support for solving the clogging issue, and promoted the high-efficient utilization of brackish water in saline areas