Abstract: A seed dispensing mechanism for a precision row crop planter employs a pressure differential to cause seeds to be held to a series of seed apertures in a rotary disc. The disc is of stainless steel of very thin gauge whereby the disc deforms under the pressure differential to provide a degree of self sealing. The apertures in the disc are formed by chemical etching. A singulator mechanism for removing excess seeds from the apertures comprises singulator members on opposite sides of the row of apertures and presenting a curved profile to the seeds and defining a throat of which the width can be adjusted by a single knob through a high ratio adjustment mechanism.