Soil surface crusts can severely limit water infiltration and tree crop production. Vegetative cover and gypsum treatments in an orchard increased soil structural stability and may reduce crust formation in the long term. Tillage improved short-term water penetration by temporarily breaking up the crust.

This research received funding through the Kearney Foundation of Soil Science 1986–91 mission “Water Penetration Problems in California Soils.” The authors thank Greg Correa, Onstott Orchards, for his cooperation, and Richard Pelton, UC Davis.