Leached manure—a promising soil anti-chustant

Planting of lettuce and other vegetable crops to a stand in California is often hampered by soil crusting. Materials used to deal with this problem include petroleum mulch, stabilized vermiculite, and phosphoric acid, but, because of cost, application difficulties, and other reasons, they are not always acceptable. Numerous materials and techniques have been tested to solve the problems associated with soil crusting, but none has proved entirely satisfactory. One that shows promise is steer manure, but it must be properly prepared for use. Several experiments have been completed in which specific numbers of lettuce seeds were planted, covered with steer manure, and evaluated for percentage and velocity of emergence and seedling growth rate.