Effects of Arkansas Cotton Production Systems on Soil Strength

In recent years, many Arkansas cotton producers have adopted conservation tillage, often including winter cover crops, to improve soil quality and prevent erosion. However, no-till and reduced tillage systems do not allow the frequent tillage that has historically been used to help alleviate deep soil compaction problems in this region. To better understand the effect of tillage system on soil compaction, a three-year experiment was conducted in eastern Arkansas to compare effects of the following three tillage systems on soil strength: conventional tillage, no-till, and reduced tillage with a cover crop. A soil probe was used annually after cotton harvest to obtain a full set of cone index (CI) and electrical conductivity (EC) data at five locations across the row, with six replications of each plot x row position combination. Soil moisture for each treatment was determined from soil cores collected at two depths. First-year CI values indicated possible root-limiting conditions below the 30-cm depth in all treatments, but were greater in no-till and cover crop treatments than in conventional-tillage plots. However, tillage treatment showed very little effect on CI in the second year, and no-till treatments had the lowest overall CI values in the third year, regardless of row position, indicating the no-till system gradually decreased compaction in the soil profile at 20-cm depths and below. Although relatively high CI values were still detected from the surface down to a 20-cm depth in all treatments, cotton lint yields did not indicate that soil compaction caused any severe restriction on cotton root growth. Furthermore, these high CI values were shallow enough in the no-till system that in-row chiseling or strip-till that does not disturb more than 30% of the soil surface may be a viable option for decreasing soil compaction if it begins to limit crop production in these systems.