Water repellency occurs when hydrophobic (or water repelling) waxy materials originating from plant residues decompose and coat soil particles preventing the infiltration of water into the soil profile. Soils with a small surface area (e.g. sand) are more prone to water repellency as it takes less hydrophobic material to coat individual particles, compared to silt or clay. The result of water repellency is generally uneven water distribution in the soil profile which leads to patchy and uneven plant emergence. Water can remain ponded on the soil surface to be evaporated or lost as runoff. Lack of plant cover and heavy autumn or summer rains can result in significant runoff and erosion on sloping paddocks. Non-wetting in Western Australian soils can be related to the hydrophobic nature of native and leguminous plant residues. However, there is generally no direct relationship between total soil organic carbon.