Penterra PENTERRA2.5 2.5gal Soil Surfactant gets water moving through the soil profile faster than any other product. It is a highly effective soil penetrant and soil surfactant product for addressing hydrophobic profiles and horizons. Penterra keeps soils from locking up. It aggregates soil, including clay soils that need it most. Penterra improves soil structure and allows water and oxygen to better reach plant roots. This fast soil penetrant does this by reducing the surface tension between the water and the soil.