Submitted to: Arkansas Agricultural Experiment Station Special Reports
Publication Type: Experiment Station
Publication Acceptance Date: 5/21/1995
Publication Date: N/A
Interpretive Summary: Cover crops protect soil from erosion and prevent leaching of crop nutrients to groundwater. Between 1989 and 1994, we compared soil strengths for plots where cotton was grown with and without rye or vetch winter cover crops. Some plots were surface tilled, which is the conventional practice in many areas of the southeastern Coastal Plains, and dothers were not. All plots were deep tilled, only in the row below the cotton crop, just before planting to break up a subsurface hard layer. Neither the cover crop nor the surface tillage affected the soil strength enough to reduce yield. The deep tillage loosened the soil below the row enough to let roots grow below the pan and extract water from lower layers of the soil. Soil strengths below the mid-rows, where there was no deep tillage, were high enough to prevent root growth. The highest soil strengths were found below the mid-rows where there had been wheel traffic. .Though some deep tillage is necessary to break up the pan, cover crops can be grown to protect the soil in winter and not reduce cotton yields. Also, eliminating surface tillage can save energy without loss of yield.
Technical Abstract: We grew cotton with or without winter cover crops in the southeastern Coastal Plains for five years between 1989 and 1994. Soils were conventionally tilled (disked in spring) or conservation tilled (not disked). Winter cover crops and conservation tillage had higher soil strengths than no winter cover or conventional tillage, respectively. These differences were generally not enough to reduce yield. Despite the increase in water content with depth, soil strength increased with depth except for a high strength pan at 11 in. This pan is the reason for the in-row subsoiling requirement of most tillage management systems. Soil strength was highest in the wheel-track mid-row, next highest in the non- wheel-track mid-row, and lowest in-row where the subsoiler had disrupted the soil. Subsoiler disruption is enough to allow root growth through the pan into the softer, structured soil below it.