Performance of powered disc coulters under no till crop residue in the soil bin

Three types of 460-mm-diameterdisc coulters were power-driven to evaluate their crop residue cutting ability in the soil bin. Rotational speeds up to twice the travel speed were used in the tests. Power consumption, draft and vertical forces were measured without straw and with straw density ranging from 1000 kg/ha to 5000 kg/ha. Observation and analysis of data indicated that the straw cutting performance of the plain coulter was nearly 100%. With the notched and the serrated coulters, the quantity of straw cut increased with the increase in the rotational speed and decreased with the increase in the straw density. Draft and vertical forces increased with the increase in the rotational speed and the straw density, but were considerably lower than those obtained with the free-rolling coulters. Power consumption increased with the increase in rotational speed and with the straw quantity. Since increasing the rotational speed of coulters to twice the travel speed had no effect on the quantity of crop residue cut, powering the coulters for no-till drills may not be desirable. A plain free-rolling coulter of approximately 460 mm diameter will perform satisfactorily under no-till practices over a wide range of crop residue density.