Effects of a plow-pan in an orchard— interference with normal distribution of tree roots and with the rate of water penetration into the deeper soil layers— can be counteracted to a considerable degree by a soil management program.

The above progress report is based on Research Project No. 768

The apparent soil density determinations at Davis were made by senior student Walter Gumboil, and the root distribution and apparent soil density study at other locations were conducted by graduate student T. C. Tomich, under the direction of Professor Proebsting