The effect of power harrow on the wheat residue cover and residue incorporation into the tilled soil layer

Preferred alternatives of residue management leave some part of residue on the soil surface and incorporate the remaining part of it into the soil. The ability of some passive tillage implements is not acceptable for residue management. A power harrow which is commonly used in Turkey for reduced tillage, with two different ground driven types of rollers and various operating conditions was used to determine its effect on the distribution of wheat residue cover on the soil surface, the amount of incorporated residue into the soil, soil physical properties and fuel consumption. The experiment was designed with two different blade peripheral speeds (3.09 and 3.44 m s-1), three tractor forward speeds (0.58, 0.92 and 1.26 m s-1) and two different types of ground driven rollers (heavy and light type) as treatments and with three replications. According to the obtained results tractor forward speeds affected fuel consumption, the residue cover and residue incorporation values. Generally, a negative relationship was determined between tractor forward speeds, fuel consumption and residue incorporation. Increasing the blade peripheral speed increased fuel consumption and the residue incorporation rate. However, there was a negative relationship between the blade peripheral speed and the residue cover (p < 0.01). Maximum fuel consumption and residue incorporation were observed in the plots in which the heavy roller was used compared to the light type roller. The incorporation effect of the power harrow incurred mostly at the top of the working depth and the mixing corn tracer was generally kept between 2 and 6 cm at the upper tilled soil layer. No significant changes occurred in soil bulk density and penetration resistance values as a result of soil moisture content which was very low when the experiments were conducted. It would be very beneficial to choose the ratio of blade peripheral speed to tractor forward speed based on blade trajectory analysis when deciding the intensity of soil tillage, which could be shown in the user's manual of power harrows.