Much interest has been expressed in compounds to reduce field curing time of forages. The desiccants that are effective contain potassium or sodium carbonate. These compounds disturb the waxy cuticle of the alfalfa stem to allow it to dry faster. Desiccants work only on legumes such as alfalfa, trefoil, and clovers. Effectiveness varies with climatic conditions.
Desiccants reduce drying time most when drying conditions are good.
Thus, they tend to work better on second and third cuttings in Wisconsin. They are recommended for hay making and are of less usefulness when forage is harvested as haylage. Preservatives are applied to the hay as it is harvested and prevent heating and spoilage of hay baled at high moisture contents. Preservatives are cost effective if used only when needed to prevent rain damage to hay and if applied uniformly to windrow as it is entering the baler. When purchasing preservatives, compare cost on a per pound of propionic acid basis.