The study included 13 substrates with different ratios of four media components. Four species of plants were grown (Vinca, Verbena, Impatiens, and Petunia), each with two replicate plants of each of the 13 substrates.
Each 1 Liter container, with approximately 850 mL of media volume, was fully hydrated and weighed to determine a maximum mass. Plants were then grown for three days until they wilted. Wilting was visually quantified on each pot. When the plant wilted, the container was weighed again to determine the minimum mass. The container was then re-‐hydrated to determine a second replicate maximum mass. The two fully-‐ hydrated, maximum masses were averages. The difference between the maximum and minimum masses was used to calculate the water holding capacity (Percent Available Water, PAW; assuming a constant 850 mL substrate volume) for each container.
Johnson, Jakob; Wheeler, Will; Braddy, Mara; and Bugbee, Bruce, "Effect of Wood Chips and Rice Hulls on Water Holding Capacity of a Peat‐based Substrate" (2017). Plants, Soils, and Climate Faculty Publications. Paper 802.