“…The relationship of good physical conditions in the soil to crop yield (8, 12,13,16) and to effective control of runoff and erosion ( 10,12,15) has been pointed out. In previous reports of results from studies on controlled plots (7,12) we have shown the benefits of crop rotation and organic matter additions on soil physical conditions, control of runoff and erosion, and improvement of truck crop yields. Results from studies here and elsewhere (8, 11) have indicated that the soil management and organic matter maintenance practices most favorable for efficient crop production and those most favorable for conservation of soil and .water are similar in most respects.…”