Development of a fuel consumption equation: Test case for a tractor chisel-ploughing in a clay loam soil

• The general equation of fuel consumption for an MF-399 tractor has been developed.
• Results were compared to fuel consumption rates predicted by ASAE Standards D497.4.
• The validation process proved that the fuel consumption models were acceptable.

Fuel consumption and tillage draught were measured when chiselling in a clay loam soil in Badjgah Research Station, Shiraz University, Shiraz, Iran. An 81 kW tractor (MF-399) instrumented with a data acquisition system was used to measure fuel consumption, actual forward speed, theoretical forward speed, slip and implement draught. The effects of blade width (5 and 10 cm), tillage depth (10, 15 and 20 cm) and actual forward speed (3, 4 and 5 km h−1) upon fuel consumption were investigated. Fuel consumption was assumed to be a function of wheel numeric, slip, net traction ratio, rolling resistance ratio, chisel-tool aspect ratio and actual forward speed. Collected data were used to model the tractor fuel consumption using dimensional analysis approach. Results were compared to fuel consumption rates as predicted by ASAE Standards (D497.4). The comparisons showed that the standard overestimates fuel consumption by 26–53%. Results from regression (F-test) between predicted and measured fuel consumption data showed that the slopes for fuel consumption with the 5 and 10 cm blade widths were not significantly different from 1:1 line (P ≤ 0.05). Consequently, the fuel consumption rate can be successfully predicted by the model with good accuracy.