The purpose of this study was to evaluate the effect of peripheral speed of the disc in pneumatic and horizontal plate metering mechanisms, with corn and soybean seeds, in laboratory test. The treatments consisted of four peripheral speeds (0.09, 0.18, 0.28 and 0.38m s-1) in combination with four metering mechanisms (two pneumatic and two horizontal plate) in split-plot design with three replications. The mechanisms were compared by mean test and, for peripheral speeds, draw up regression equations. The index of the acceptable, multiple and fail between seeds through the theoretical nominal spacing's resulting from each treatment. The acceptable spacing's index decreased linearly with increasing peripheral speed of the disc to both cultures. For corn, the pneumatic metering mechanisms showed better results to the horizontal plate in higher peripheral speeds. For soybean, the pneumatic feeders performed better on the average of treatments. In general, how much lower the peripheral speed of the plate, better the regularity of seeds distribution of corn and soybean.
acceptable index; quality of feed index; precision seeder; pneumatic seeder.
