Furrow parameters in rotary strip-tillage: Effect of blade geometry and rotary speed

Abstract

Two-wheeled tractors fitted with rotary cultivators are used in many developing countries for full disturbance soil tillage. Recent development, motivated by the benefits of conservation agriculture, is working toward strip-tillage seeding using two-wheeled tractors fitted with modified rotary cultivators and seeding attachments. The effect of three blade geometries (conventional, half-width and straight) at four rotary speeds (125, 250, 375, and 500 rpm) on the furrow seedbed parameters when used for strip-tillage was investigated. The experimental blades were mounted on a rotary tiller test unit operating in a reconstituted sandy loam soil travelling at a forward speed of 0.67 m s−1. Analysis of the high-speed video showed that the straight blade reduced the soil carrying and throwing. At 125 rpm all blades produced either an unsatisfactory cloddy seedbed with an irregular furrow bottom and walls or an incomplete furrow. At 500 rpm, considerable amounts of soil were thrown out of the furrow for the conventional and half-width blades which achieved furrow backfills of only 41 and 36%, respectively. The straight blade achieved the fullest backfill at 74% even when operating at 500 rpm. The level of soil pulverisation increased with rotary speed, but was not affected by blade geometry. Each of the blades produced different furrow shapes with a higher furrow volume tilled by the conventional and the straight blades compared to that by the half-width blades. Based on its high backfill and large furrow volume, the straight blade would be the preferred option when undertaking rotary strip-tillage.