The Water Infiltration, Hydraulic Conductivity and Water Retention Effects of Ground Soapwort (Saponaria officinalis L.) Root as a Soil Surfactant

Climate change is affecting precipitation patterns and intensity; increasing regional drought conditions and increasing runoff, respectively. The use of soil surfactants presents an opportunity to improve soil water content and infiltration in soils. As aridity and drought vulnerability increase globally, improving water infiltration and retention is becoming increasingly important for agriculture as water resources are scarce and climate change shifts precipitation patterns. While surfactants are widely available for agricultural use, most or all are unapproved in sustainable and organic production. Ground soapwort (Saponaria officinalis L.) root produces saponins, natural surfactants used in several industrial applications, including soap manufacturing and soil contaminant recovery. To determine its potential to improve soil water interactions its effects on soil hydraulic conductivity, water content, infiltration and drainage rates were tested in washed sand, heavy clay soil and clay loam soil. When compared to untreated soils, drainage and infiltration was slowed (P < 0.05) in sand and loam with soapwort applications while no significant differences in any variable were present in clay soil compared to any treatment. Soil water content was not significantly different in any treatment. While soapwort did not increase infiltration rates it did markedly slow drainage rates in sand and loam. The benefit of this may be realised as longer opportunity for plant available water in the root zone.