Penetration Forces at Different Soil Conditions for Punches Used on Punch Planters

Penetration forces of punches designed for use in a no-till punch planter were evaluated for two soils at three different moisture levels and three bulk density levels. The standard cone penetrometer was used as a reference. A procedure using PVC molds for preparing standardized soil samples, measured penetration resistance at 40, 60, and 80 mm. The penetration forces for two punch widths approximately doubled at each depth interval. Soil moisture content at typical field conditions required the highest penetration forces. Changes in bulk density resulted in the biggest changes in penetration force. At median moisture level, increments of 0.15 Mg/m3 in bulk density for a silt loam soil and of 0.20 Mg/m3 for a sandy loam soil resulted in approximately a threefold increase in penetration forces. A good correlation was observed between the cone penetrometer data and the penetration forces for the two punches.