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 w as used to locate four distinct tilled zones for evaluation. Field tes t results on measured soil properties indicated a significant main eff ect of the ratio of rotor peripheral velocity to machine velocity (lam bda) and an interaction effect of blade shape, tractor tire traffic, a nd blade overlap intensity. Thirty-four days after rotary tillage, a h igher lambda (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 th e 0 to 5 cm and 10 to 15 cm soil depths with the higher lamdba. Genera lly, the soil physical conditions were densest in the soil tilled with flat blade tines in the tire track where strong overlap between rotor s occurred.