Determination of Optimum Plant Population for Soybean Agronomic Productivity

The poor agronomic practices, such as seeding rate and inappropriate plant population are the major reasons for low productivity of soybean. A field study did to determine the appropriate row and plant spacings for Soybean productivity and profitability at Metema and west Armachiho districts. Treatments were arranged to five rows (30, 40, 50, 60 and 70 cm) with three plant spacings (5, 10 and 15 cm) comparing with the blanket recommendation (40 cm x 10 cm and 60 cm x 5 cm) and laid out in randomized complete block design with three replications. The Afgat variety was used as planting material and 121 kgha<sup>-1</sup> of NPS fertilizer was applied at sowing time. The combined results indicated that; days to 50% flowering, number of branches plant<sup>-1</sup>, length of productive node, number of seeds pod<sup>-1</sup>were significant, whereas days to 90% physiological maturity, plant height, number of pods plant<sup>-1</sup>, hundred seeds weight and grain yield were highly significant (p < 0.01) and affected by the interaction effects of inter and intra row spacings. The highest grain yield (3831 kgha<sup>-1</sup>) and net benefit (50,650 ETB/ha) were obtained from the combination of 40 cm row spacing with the 5 cm plant spacing. Whereas, the blanket recommendation (40 cm x 10 cm and 60 cm x 5 cm) gave 3556 kgha<sup>-1</sup>and 3519 kgha<sup>-1</sup>, respectively. Therefore, 40 cm the row with 5 cm plant spacing is suggested to be promoted for Soybean production on the low land areas of northwestern Gondar, Ethiopia.