Gypsum Improves Water Efficiency
Gypsum provides many benefits to the soil including water storage. Calcium sulfate impacts soil structure which influences its ability to capture and store water.
Calcium in gypsum helps flocculate soil particles together into more naturally aggregated peds that improves structure and increases porosity. This probably is gypsum’s primary benefit to soil from which all other benefits exist.
Calcium flocculates clay particles in the soil. Flocculation is the process in which many individual small clay particles are bound together to give large peds. And peds glue together to form aggregates, a grouping of much larger peds. Flocculation is needed to give favorable soil structure for root growth and air and water movement.
Gypsum improves water infiltration rates into soils and also the hydraulic conductivity of the soil or movement of water through the soil. The more porous the soils and the bigger the soil pores, the faster water can move. Think of a sandy soil with large particles that don’t fit tightly together and have a lot of big pores and water drains through quickly.
Additionally, gypsum contains soluble calcium, which helps loosen tight soils. By adding a source of soluble calcium to any clay soil or sodium (sodic) or magnesium soils, you improve aggregation and increase porosity and enhance air-water exchange within the soil.
Often one of the problems with soils containing clay (which most soils have), is that fine clay particles break away from soil aggregates (and particularly when tilled or after a heavy rain or irrigation on bare soil) and settle on top of the soil, forming a cement line layer or crust. Water can’t infiltrate this crust.
Gypsum can prevent or eliminate crusting on soil surfaces. Prevention of crusts means more water can infiltrate, which leads to better seed emergence and more rapid seedling emergence.
Crop growth can be impeded by lack of root growth due to poor soil structure, composition and increased soil density. Gypsum can help improve root growth. The more open and porous the soil, the better the root growth. This improved root growth enables roots to explore a larger volume of soil and capturing more available water. Ultimately, soils with optimum soil structure produce higher yields. In acidic soils, and particularly subsoils, aluminum becomes more soluble and is toxic to roots and decreases root growth. Calcium will displace the aluminum so it leaches out of the root zone.
If you have used gypsum in a field or on your garden, have you noticed an increase in water holding capacity of the soil as well as better rooting?