Design and development: The main components of the planter are (i) frame, (ii) seed hopper, (iii) inclined plate seed metering device, (iv) seed delivery tubes, (v) furrow opener, (vi) soil compaction roller, (vii) dock clutch, and (viii) chain sprocket.
(i) Frame: The main frame is made of 4 cm x 4 cm M.S. angle bar of 90 cm length, 100 cm height and 70 em width. The furrow opener, seed tube, seed hopper, metering plates, gear assembly, chain-sprocket, soil compaction roller, dock clutch, etc. are attached to the main frame.
(ii) Seed hopper: The seed hopper is made of 18 gauge M.S. sheet of 90 ern length, 18 em width and 20 cm height. It has 4 openings (45 mm x 40 mm) at 18 ern apart at the rare side of the hopper. The metering plates deliver the metered seed into the opening at the top of the delivery tubes and pass through the seed tubes to the furrow.
(iii) Inclined plate seed metering device: The metering device of the planter is an inclined (60°) plate edge-dropping cell. The cells are located around the periphery of the plate. The metering plate passes through the seed reservoir under the baffle plate separated from the main hopper. Seeds are picked in the cells and dropped on the top of the inlet of the delivery tube. A stationery baffle is provided for unloading surplus seeds. These devices for planting and handle the seeds gently. Metering plates are made of aluminum. These plates get power from power tiller driving wheel shaft. The seed-metering unit has 3 components as (a) metering plates, (b) chain sprocket arrangement to operate metering plates through bevel gear matching, and (c) dock clutch.
(iv) Seed deliver tubes: The metering plates deliver the metered seed into the opening at the top of the delivery tubes and pass through the seed tubes to the furrow. Seed dropped by the metering plate have two relative motions with respect to the ground. With respect to the delivery tube, the motion of seed is only along x-axis (direction of travel) because there is no rotational speed of the seed as it is under gravity fall. The path described by the seed with respect to the seed tube is a free fall and initial vertical velocity of the seed at the time of deli very from the metering plate cell is zero.
Furrow opener: Specially designed furrow openers were introduced in the planter to place seeds at desired depths without any trouble. M.S. angle (25 mm dia) of 25 cm length was used in making the furrow openers and was fitted on the bottom of the main frame.
Soil compaction roller A soil compaction roller, made of 20 gauge M.S. sheet was fitted with two self-centered ball bearings, behind the furrow opener with the main frame. In case of minimum tillage planting, ploughing depth was controlled by this' soil compaction roller. For conventional planting, depth of planting was adjusted by furrow opener height
Field performance test of the planter The planter was tested at Bangladesh Agricultural Research Institute, Joydebpur, Gazipur. It was operated by a 12 hp power tiller at a speed of 1.5-4.0 km/hr. Before planting, the seed-metering plate for particular crop was fitted to the seed hopper. The metering plate is uniformly rotated and there is no missing cell as the constant power form the driving wheel axle through dock clutch is obtained. Maize seeds were planted at 3-4 cm depth with a row spacing of 75 cm and plant to plant spacing of 25 cm. The planter covered 2 rows in single pass. Maize seed rate was 22 kg/ha. Wheat seeds were sown at 3 em depth and row spacing of 20 ern. The planter covered 4 lines (80 cm width) in single pass and the seed rate of wheat was 100 kg/ha. After germination of seeds,. plant population was counted.