In this article a strain gauge type brushless torque meter was designed and fabricated. The innovative part of this apparatus is the data logging system which uses MMC card. To accomplish this goal, a compact electronic circuit was designed, constructed and mounted on a special connecting shaft rotating at 1080 rpm and transmitting power from tractor's pto shaft to a silage corn harvester. In order to evaluate the system linearity and repeatability, static laboratory test was performed. The output signals showed excellent linearity and also repeatability with high correlation with transmitted torque changes. Field test was also conducted to evaluate the performance of this torque meter as a real time mass fl ow rate sensor in silage corn yield monitoring. Results showed high correlation between electronic circuit’s output and mass fl ow rate with R2 of 0.97. Finally a silage corn yield map was prepared using this technique for a typical test fi eld