A practical method for determining substrate capillary water sorption
The effectiveness of a horticultural substrate to capture (or absorb) and retain water through irrigation can be an important factor in a sustainable plant production system. Reduced substrate wettability can lead to less water captured, excessive leachate and poor plant growth. Taking into account hydraulic properties and substrate physical characteristics, hydration curves can be derived through subirrigation to understand the capillary uptake potential of soilless substrates. To better understand capillary potential, a low cost, practical system was developed to examine the relationship between wettability and hydration through subirrigation. Using ebb and flood subirrigaton, we developed hydration curves and calculated the rate at which water entered the substrate to determine the change in water uptake under specific treatment conditions. Experiments were conducted using Canadian sphagnum peatmoss, coconut coir, and aged pine bark under moisture contents ranging from 33 to 67%. The practical implications of this method span further than capillarity, also being used for determining substrate container capacity, the effect of irrigation pulsing regimens, and efficacy of wetting agent applications.
Schulker, B.A., Jackson, B.E. and Fonteno, W.C. (2021). A practical method for determining substrate capillary water sorption. Acta Hortic. 1317, 327-334
wettability, water capture, growing media, substrate hydrology, subirrigation