Fig. 1. The interaction of depth and rotation for pH after 30 yr of crop rotation on a Reading and Muir silt loam. An asterisk indicates significant differences between rotations for the same depth (
= 0.05). Key to rotations: SOSO = continuous grain sorghum; SYSO = soybean-grain sorghum; SYSY = continuous soybean; WHSY = wheat-soybean; WHWH = continuous wheat.