Hydroponic systems and water management in aquaponics: a review

Hydroponics is a method to grow crops without soil, and as such, these systems are added to aquaculture components to create aquaponics systems. Thus, together with the recirculating aquaculture system (RAS), hydroponic production forms a key part of the aqua-agricultural system of aquaponics. Many different existing hydroponic technologies can be applied when designing aquaponics systems. This depends on the environmental and financial circumstances, the type of crop that is cultivated and the available space. This chapter provides an overview of different hydroponic types, including substrates, nutrients and nutrient solutions, and disinfection methods of the recirculating nutrient solutions.

In the Mediterranean arid and semi-arid regions, large amounts of low quality waters could be used for crop irrigation, but the adoption of articulated classifications with too rigid quality limits can often reduce the recoverable quantities of water and make the monitoring of water quality too much expensive. Therefore, an evaluation of irrigation water quality based on only a few crucial parameters, which consider the crop species to be irrigated and the type of irrigation system and management adopted, can be an easy and flexible method for maximizing the reuse of wastewater and low-quality water for agricultural purposes. In this view, an irrigation water quality tool (IWQT) was developed to support farmers of arid and semi-arid regions on evaluating the use of low quality water for crop irrigation. The most significant and cheapest parameters of irrigation water quality were identified and clustered in three quality classes according to their effects on crop yield and soil fertility (agronomic quality indicators), human health (hygiene and health quality indicators), and irrigation systems (management quality indicators). According to IWQT parameters, a tool reporting a series of recommendations, including water treatment types, was implemented to guide farmers on the use of low quality irrigation water.