Soil hydrophobicity as a strategy for water harvesting

Banksia plants have a double system of surface and deep roots. Banksia roots are able to induce soil hydrophobicity, possibly from exudates and association with the soil microbiota. The photograph shows a detail of a pore through a cluster of roots of Banksia attenuata, from the Banksia restoration area at Gaskell Avenue Quarry, WA, Australia. Rainfall water is retained in the first 1-2 cm soil layer on a hydrophobic horizon formed by surface banksia roots and percolates through macropores (galleries dug by animals, cracks or channels of old dead roots). Infiltrated water reaches soil deep layers and is collected by the deep root system of Banksia, as a successful strategy for the use of scarce water in arid systems.