A new metering system having vertical rotary disc used for feeding potato tubers planter, manufactured and tested to determine the performance and reducing the operation cost. The modified planter was tested to suit planting potatoes with four traveling forward speeds of 3.1, 3.8, 4.7 and 5.6 Km/h, four planting spaces of 18, 24, 29 and 37.5 cm and three levels of planting depth was 5, 7 and 10 cm . The results indicated that, maximum of machine field capacity was 1.2 Fed/h and field efficiency was 78.5%. Also, maximum of emergence ratio was 98.9%, seed tuber spacing uniformity was 88.5% and specific fuel consumption was 0.812 l/kW.h. On the other hand, minimum of missing tubers ratio was 0.9%, duality tubers hill ratio was 0.2%. Also, optimum operation cost was 34.5 LE/h and criterion function was 233.15 LE/h recorded with forward speed of 4.7 Km/h, planting depth of 5 cm and planting spaces of 24 cm.