Stability and Effectiveness of Wetting Agents in Stored Growing Media

Abstract

Three soilless media of different composition (peat: vermiculite, bark: peat: vermiculite, peat: vermiculite: polystyrene) received one of three wetting agent treatments (AquaGro 160 at 60 ml or 120 ml·m–3; or AquaGro L at 120 ml·m–3) and were subsequently analyzed for wettability after storage for up to 4 months. The respective untreated media served as the controls. All media were stored in closed bags at 24 ± 4C. Water retention was greater in wetting agent-treated media than in controls. Both wetting agents facilitated uniform distribution of water in the media. Control media became more difficult to wet over time, whereas wetting agent treatments maintained uniform wettability of media throughout the storage period. Wetting agent chemistry, treatment rate, and media composition influenced wetting characteristics during media storage. All three wetting agent treatments improved wetting of the peat: vermiculite over the 4-month test period. In bark media, AquaGro 160 applied at 120 ml·m–3 enhanced wetting throughout the study. Media containing polystyrene were difficult to wet. AquaGro 160 applied at 120 ml·m–3 improved wetting for up to 2 months.