Surfactants as Soil Wetters
Soils can be naturally hydrophobic in nature; this is often exacerbated when the soil is left to dry for an extended time or has a high organic content. Soil hydrophobicity can lead to water pooling and surface run-off, which has a direct consequence on plant growth through restriction of water infiltration and supply to a plants’ root zone in the case of turf grass and field crops. Soil quality and physiochemical properties can directly affect the penetration and percolation of water throughout the soil profile.
Agrochemical treatments, in particular pre-emergent herbicides are often applied directly to soil, which is naturally a hydrophobic substrate and doesn’t interact favourably with water. The hydrophobic nature of the soil can limit the penetration and infiltration of irrigation-based applications. Consequences of such unfavourable interaction can lead to surface run-off and reduced percolation and distribution of water within the soil.
Poor soil penetration is caused by the surface tension of the droplet. Breaking down the surface tension allows the droplet to collapse and spread over the surface, wetting it thoroughly without running off. Surfactants are one of the best ways to reduce this surface tension and therefore can be applied in formulations or at tank side to improve soil penetration of agrochemical treatments to control soil borne diseases like nematodes and fungus.