EcoGEM. Can gypsum be applied on organic farms?
Commercial farmers, organic farmers, home owners, turf managers and others can benefit from application of gypsum (calcium sulfate) in remediating salinity and sodium issues and improving soil structure. However they can’t all use the same sources or gypsum.
Mined gypsum can be OMRI® listed (Organic Materials Review Institute®), which OMRI is a national nonprofit organization that determines which input products can be used in organic crop production. Many natural gypsum suppliers have gotten this certification. OMRI listed products can be used in certified organic operations under the USDA National Organic Program.
However many sources of synthetic gypsum can’t get an OMRI listing. Gypsum sourced from flue gas desulfurization (FGD) systems at electric power plants and can carry some metals is not OMRI listed. Other forms of synthetic gypsum include by-products of citric, lactic or phosphoric acid manufacturing plants, water treatment plants as well as recycling wall board.
An organic farmer or gardener creates compaction from trafficking or tilling that compresses the soil and destroys soil structure. These activities create poor drainage and aeration, soggy soils and reduced root growth. Manure, compost, peat moss and soil mulches and soil conditioners all help in building soil structure and help it resist compression and destruction.
Gypsum is another solution for reconditioning the soil, because it can be spread on the surface of the soil and does not have to be incorporated since it is very soluble. Gypsum, once solubilized, penetrates clay particles in heavy soil or the layer of hard subsoil type soils and loosens soil structure. Then this creates air and moisture slots that will loosen and break- up the soil structure.
Mined gypsum can be used in organic production but industrial by-products aren’t allowed.