Abstract
The experimental studies were made to find the capability of the precision planting of small and irregular seed with vacuum metering device. The results obtained are as follows.
(1) In case that the direction of the orifice was the same as the movement of the nozzle in the seed box, picking up rate was higher than the other cases. When both directions made a right angle, not only the rate was inferior to that of the same direction, but also higher vacuum pressure was required.
(2) Picking up efficiency was influenced directly by the suction air-flow rate. The adequate amount of suction air-flow to get maximum picking up rate of single seed was found experimentally for the various kind of seeds.
(3) The relation between sectional area (A) of the orifice in the region of 0.4-1.0mm of the diameter and the flow rate (G) of air could be shown as follow.
G=A2√2gγP/0.00087+1.316A
(4) Maximum picking up rate of single seed and adequate amount of the suction air-flow under the various experimental conditions were obtained. (Table 2)
The adequate flow rate of air was approximately relative to the logarithm of the weight of seed. (Fig 11)
Because surface of heavy seed was comparatively smooth, in generally, the leak of airf-low around the seed and adequate amount of air-flow per weight of smooth seed, were not so much. For the coated seed of sugar beet, little double seeds was picked up, and the single seed reached 100per cent for the suction air-flow of more than 0.05g/sec.
(5) Increasing the velocity of nozzle (contact velociy to seed), rate of picking up decreased. This decrease of the rate could be supplemented by increase of flow rate.
It was considered that the ratio (G/v) of the flow rate (G) to get maximum picking up rate of single seed to the velocity (v) of nozzle showed constant value for each kind of seeds.
