The objective of this study was to investigate the effect of tractor power and forward speed on the drawbar pull, wheel slippage and fuel consumption when a 2WD tractor was linked with  a mounted disc plow and working on  a clay loam soil. Two levels of tractor drawbar power and three levels of forward speed were evaluated. Results showed that the  increase in tractor power   and speed and their interaction  had a highly significant effect on these three field performance parameters. It was found  that  as the tractor power increased from 53.2 kW to 68.4 kW, the average pull increased by 55%, while the increase in tractor speed from 5 km/hr to 9 km/hr increased the pull by 39% and 36%  for the medium and large tractors, respectively. When  the power of the tractor was greater, the average wheel slippage was reduced up to 55%, but when the higher speed was used the average slippage was increased by 31% and 12% for the two tractors, respectively. The average fuel consumption rate was observed to be increased with the increase in tractor power and speed giving an average  increase of 60% with the bigger  tractor. However, using the  higher speed gave an average increase in fuel consumption of 72% and 60% for the two tractors, respectively. The multiple correlation analysis indicated that   power and  speed accounted jointly for 98.1%, 97.7% and 92.6% of drawbar pull, slippage and fuel consumption rate variability, respectively. The big tractor (68.4kW) working at medium speed  7km/hr showed  a tendency to give optimum values of the three field parameters operating on this type of soil.