Powered Harrow Operating Parameters: Effects on Soil Physical Properties

Operating parameters of a powered harrow were investigated on a Kokomo silty clay loam soil. Kinematic analysis on the rotary blade’s path was used to locate four distinct tilled zones for evaluation. Field test results on measured soil properties indicated a significant main effect of the ratio of rotor peripheral velocity to machine velocity (l) and an interaction effect of blade shape, tractor tire traffic, and blade overlap intensity. Thirty-four days after rotary tillage, a higher l (3.87 compared to 2.75) reduced both air porosity and air permeability by 26% in the 5 to 10 cm depth. Cone index measurements, 23 days after tillage, revealed a significantly higher strength in the 0 to 5 cm and 10 to 15 cm soil depths with the higher l. Generally, the soil physical conditions were densest in the soil tilled with flat blade tines in the tire track where strong overlap between rotors occurred.