Hydrophobic Soil

Hydrophobic soil in established turf areas.

With the forecast for a bit of rain later in the week in Newcastle, now is the time to act. After months and months of dry hot weather the soil beneath your grass has more than likely become hydrophobic. 

What is hydrophobic soil?

A water-repellent soil (or hydrophobic soil) does not wet up spontaneously when a drop of water is placed upon the surface. It is common to see water pooling on the surface of dry soil rather than being absorbed by the soil. In turf, this translates into “dry patches” or localised dry spots - irregular shaped areas where the grass or other plants suffer from drought because the repellent soil below does not wet up uniformly following rain or irrigation.

What causes it?

Soils become hydrophobic when they are dry for extended periods - particularly when the dryness is combined with a high organic content. Hydrophobic soil is caused through the production of complex organic acids during the decomposition of organic matter. These complex organic acids are wax- like substances that form a coating over particles of soil.

How do you fix this problem?

The simplest way to make your soil absorb the water is by using a wetting agent. These impact on the waxy residues in the same way washing detergents impact grease and fat particles in your washing up. By reducing the surface tension of the water, the moisture can more easily penetrate the soil particle and get moisture where we need it.

Wetting agents come in granular or liquid forms. Read and follow the application instructions carefully on the back of the product you choose to use. One application of a good wetting agent will significantly reduce your use of water during hot dry periods. Common wetting agents include Wettasoil, Hydramaxx and Ezi-Wet.

Most wetting agents state that they will not harm pets, the soil or the environment, however there are organic options as well. It’s easy to make your own soil wetter from agar-agar, a naturally occurring gelling agent derived from various seaweeds and algae. You can buy it in powder form from health food shops. You can find recipes to make your own organic soil wetting agent online.

But most of all we just need rain! Let’s hope the next few days bring some much-needed rain, not only in our own backyards but in the places that so desperately need it.