Evaluation of a Pulse Fertilization Strategy for the Cultivation of Plants in Space

The recycling of water will be critical for the successful long-term cultivation of plants in space. The capture of transpired water via humidity control systems and subsequent refilling of water reservoirs feeding into plant nutrient delivery systems is an approach that accomplishes this objective, but results in a progressive dilution of the nutrient levels initially present. As part of pre-spaceflight protocol development efforts for the Water Offset Nutrient Delivery ExpeRiment (WONDER), we have evaluated the reestablishment of reservoir nutrient concentration levels via the periodic injection of 60 and 90 mL pulses of concentrated (10x) Hoaglands nutrient solution. In space this will involve crew-facilitated injections via a quick disconnect port on the payload's front panel. A study demonstrating the efficacy of this approach is presented using wheat grown on porous tubes.