Slow water infiltration is a serious problem in some orchards and vineyards on the east side of the San Joaquin Valley. It is often associated with irrigation water low in salt and soils with inherently slow infiltration rates. Gypsum, a calcium salt, is commonly used to improve water infiltration in nonsodic soils. It is the most effective with low-salinity irrigation water (electrical conductivity [EC] < 0.1 decisiemens per meter [dS/m]).