Oxygation of the rockwool substrate for hydroponics

Rockwool is one of the widely used substrate for hydroponics media in the horticultural industry. Latest research suggested that oxygen limitation occurs in the rockwool based media under both recirculating irrigation system or in a "drain to waste" (single pass) system, and roots are exposed to low oxygen level below critical in such a substrate. Our study evaluated the role of oxygation with an air injector (Venturi) for the aeration of nutrient solution in a flood and drain hydroponic system with rockwool substrate producing Chinese cabbage. The dry matter yield increased by 12%, leaf photosynthesis by 11% and water use efficiency by 39% with oxygation compared to the control. These benefits of oxygation were mediated through enhanced root processes such as increased fibrous root mass (33%), wider conducting tissues and efficient nutrient utilization by the plant when the rhizosphere wsa oxygated. Aeration of rockwool substrate hydroponics nutrient solution with an air injector offered a multitude of benefits, and being non chemical, cheaper than an air diffuser system and with low cost for installation ($200-$300 ha) and usable for more than 10 years, it may be considered as a desirable production option.