Patent attributes
A seed supply system includes a singulating meter with a seed reservoir pressurized to a meter pressure that is in a desired pressure range. A seed supply air stream carries seeds dispensed from a nurse tank to an air release assembly located above the singulating meter. As seeds are metered from the seed reservoir at a rate less than the rate seeds are dispensed from the nurse tank seeds accumulate in the air release assembly. The pressure of the seed supply air stream at the top of the seed column fluctuates and a barrier is operative to resist air flow between the air release assembly and the seed reservoir sufficiently to maintain the meter pressure in the desired meter pressure range. The barrier can be provided for example by an airlock or a column of seed in a drop tube between the air release assembly and the seed reservoir.