Application of chelated fertilizers to mitigate organic-inorganic fouling in brackish water drip irrigation systems

Organic-inorganic fouling in brackish water drip irrigation systems (BWDIS) reduces the irrigation and fertigation uniformity, resulting in decreased crop yield and quality. This study investigates the effect of chelated fertilizers on organic-inorganic fouling. Compared with control group (CK), application of Fe-ethylenediamine-di(o-hydroxy phenyl acetic acid (EDDHA-Fe) effectively prevented the multiple fouling by reducing the deposition of inorganic (precipitate and particulate) and organic fouling. Fulvic acid chelated iron fertilizer (FA-Fe) alleviated multiple fouling by drastically decreasing the precipitate and particulate fouling, although organic fouling was slightly increased. Conversely, amino acid chelated iron fertilizer (AA-Fe) slightly decreased the precipitate fouling while drastically accelerated the particulate and organic fouling, leading to severe clogging. Accordingly, EDDHA-Fe and FA-Fe prevented the BWDIS fouling by 32.6–41.8% and 16.1–29.0%, while AA-Fe accelerated by 36.9–45.4%. Moreover, chelated fertilizers (FA-Fe, AA-Fe and EDDHA-Fe) demonstrated better anti-fouling than inorganic iron fertilizer (FeSO4). However, EDDHA-Fe would have negative environmental impact, hence FA-Fe is strongly recommended from the perspectives of fouling mitigation and soil environmental health improvement efficiency. These results may provide a new guideline for applying chelated fertilizers in BWDIS to prevent organic-inorganic fouling and overcome agricultural pollution.