Assessing micro-irrigation clogging risk through water quality classification systems

Abstract

Water quality classification systems aim to assess the overall risk of clogging in micro-irrigation systems. However, their ability to predict potential clogging based on water quality characteristics remains untested, particularly in controlled environment agriculture. This project aimed to evaluate if the existing classification systems could be used to identify the cause of clogging in micro-irrigation systems in greenhouses. Water from eight commercial greenhouses with reported clogging was analyzed for physical, chemical, and biological properties to rate the risk of clogging according to the classification systems. In general, iron and manganese from the fertilizers and high microbial load resulted in high ratings. However, the ratings lacked insight into the specific causes of clogging, disregarding interactions among chemical and microbial factors and qualitative characteristics of specific microbial phenotypes (e.g., production of polysaccharides or iron oxidation) that lead to clogging. Furthermore, the systems overemphasize nutrient levels typically used in greenhouse fertigation as the cause of clogging – which is not commonly observed in practice. Enhancing these systems requires parameters reflecting these interactions and microbial traits influencing clogging. Further research needs to develop these parameters in new systems with robust and precise thresholds in which emitter performance, profitability, and sustainability are affected.