SOIL RUT EFFECTS ON PLANTER PERFORMANCE FOR COTTON IN A CONSERVATION TILLAGE SYSTEM

Soil rutting commonly occurs during harvest and ruts formed during harvesting can adversely affect row crop planter performance at the start of the subsequent cropping season. We conducted a three-year experiment on a sandy loam and a clay soil to investigate effects of soil ruts on the performance of a row crop planter while planting cotton into a rolled rye cover crop, and effects of planter depth setting on planter performance when planting through soil ruts. The four rut types used, prior to planting the rye cover crop in the fall, were a single tire rut, the rut from a dual pair of tires, and two rut types formed by cutting the soil 25 and 50 mm (1 and 2 in.) deep and removing soil from the ruts. The results show that although not all differences were statistically significant, for five of the six combinations of year and soil, cotton seedling emergence at 15 days after planting was greater when the soil had no rut, i.e., flat unrutted soil, than when the planter traveled across soil ruts while planting. In four of the six combinations of year and soil, emergence was significantly greater for the no rut soil condition than for a rut which was formed the previous fall by cutting 50 mm (2 in.) deep and removing soil from the rut. The three seeding depth settings used in the experiment positioned the bottom peripheries of the two disks of the double-disk opener 28, 35, and 40 mm (1.1, 1.4, and 1.6 in.) beneath the bottom peripheries of the depth-gauge wheels, providing those nominal seeding depths before the closing wheels firmed the soil. The planter depth setting did not signifi-cantly affect emergence at 15 days after planting for any of the six combinations of year and soil. Mean values of emergence at 15 days after planting in the sandy loam, averaged over the three years, were 13.9, 11.5, 12.2, 11.4, and 7.6 plants/m of row length (4.2, 3.5, 3.7, 3.5, and 2.3 plants/ft of row length) for the No rut, Single tire, Dual tire, Shallow cut, and Deep cut conditions, respectively. The means in the clay were 13.6, 5.7, 5.8, 12.6, and 7.4 plants/m of row length (4.2, 1.7, 1.8, 3.8, and 2.3 plants/ft of row length), respectively. Regression equations show a trend of decreased emergence as rut depth increased for both soils, with the clay regression line having a greater magnitude slope than the sandy loam line.