Effects of working depth and wheel slip on fuel consumption of selected tillage implements

Rising fossil fuel prices are leading to an increasing awareness of energy efficiency in plant production. Tillage in particular can consume large amounts of fuel. For four tillage implements (reversible mouldboard plough, short disc harrow, universal-cultivator, subsoiler), this study quantifies the effect of different working depths on fuel consumption, wheel slip, field capacity and specific energy consumption. A four-wheel drive tractor (92 kW) was equipped with a data-acquisition system for engine speed, vehicle speed, wheel speed and fuel consumption. Fuel consumption was measured in the fuel system with an integrated high-precision flow-meter. The results show that the area-specific fuel consumption increased linearly with working depth for both the mouldboard plough and the short disc harrow, but disproportionately for the subsoiler. Wheel slip was found to increase fuel consumption and decrease field capacity performance at all depths. The influence of the engine speed was shown in a separate experiment with a universal-cultivator. Increasing the engine speed from 1,513 r min-1 to 2,042 r min-1 results in an increase of 80% for the fuel consumption rate (L/h) and 35% for the area-specific fuel consumption (L/ha). Future measurement of drawbar pull will allow a more detailed analysis of the energy efficiency losses at the engine, the transmission, and at the wheel/soil interface.