Abstract
A power tiller operated potato planter cum fertilizer applicator was developed with improved seed metering mechanism which can plant both whole tuber and cut piece potato seeds automatically in furrows at predetermined regular intervals. Two types of seed metering mechanisms were developed: one cup type for whole tuber and the other pick type for cut piece seed planting. Pick type potato planter consists of two rows with spacing 500mm and cup type planter maintains a single row of spacing 600mm and maintain seed to seed distance 150mm and 250mm, respectively. The cup type potato planter singularizes the seed by a series of cups equally spaced that pass vertically through the secondary seed box for taking one piece of seed per cup. The pick type planter utilizes a disk with picks mounted on the periphery to singularize the seed. The picks pierce the seed pieces as they rotate through a magazine type potato chamber and then release the seed above the opened furrow. The planters perform four mechanical functions simultaneously, viz., opening furrow, metering the seed, applying fertilizer and making beds along with covering the seed and fertilizer. Experiments were conducted to determine the effect of forward speed and seed sizes on the uniformity of spacing, seed missing, seed injury and yield. Four speeds and three seed sizes were varied to select the optimum speed and seed size for both the planter. The effect of speed and seed size on production cost and average net benefit was found statistically significant for both the planter. Statistical analysis shows that forward speed of 2.4 km/hr is the best in respect of uniformity of spacing, yield and average net benefit. Seed sizes of 35mm and 20g were found best in respect of yield for cup type and pick type planter, respectively at the speed of 2.4 km/hr. Therefore, forward speed of 2.4km/hr and seed sizes 35mm and 20g were selected for field demonstration. Field demonstrations were conducted at different farmer's field. The average effective field capacity of cup and pick type planters were 0.10 ha/hr and 0.14 ha/hr, respectively. The average potato yield by cup type, pick type and conventional method were 22.5, 17.6 and 20.8 t/ha, respectively. In general, the cup type planter was found more efficient than the pick type planter. Potato planting cost and labour requirement by cup type and pick type planter and conventional method were Tk. 1890.0, Tk. 1397.0 and Tk.5600.0/ha, and 4, 4 and 70 man days/ha, respectively. The cup type planter saved 61% cost and 93% labour requirement compare to conventional method. Break-even point of the cup and pick type potato planter was 7.6 ha and 4.6 ha, respectively. The efficiency of resource allocation to cup type and pick type potato planter was assessed by estimating internal rate of return, net present value and benefit cost ratio under different discount rates. The internal rate of return of the investment of the cup type potato planter was estimated to be 429% at 8% df, which implies that one taka investment in potato planter would give returns on an average Tk.5.29 annually from the date of investment until the end of planter's life. The benefit cost ratios of the investments on potato planter were found to be more than 1 which indicated that both the potato planters were profitable.