Having hydrophobic soil that repels water can be frustrating. But there are many ways to fix the problem naturally and organically.
A quick fix to hydrophobic soil is using wetting agents to reduce the cohesion and surface tension of the water to better infiltrate the soil. More permanent solutions include adding organic matter and mulching to retain moisture for a longer period of time and scheduled sprinkling to prevent soil from drying out.
In this article, we will discuss in detail 8 ways to fix hydrophobic soil organically in the garden as well as in pots.
1. Use a wetting agent
Wetting agents or surfactants are the quickest and easiest way to fix hydrophobic soils.
They work on the wax-covered soil grains the same way dishwashing liquid works on greasy dishes. Wetting agents or surfactants can make it easier for water to infiltrate the soil by reducing the surface tension and cohesion between the water molecules and also breaking up some of the waxy coatings in the soil.
But they’re a short-term fix and not a permanent solution to the problem.
1.1 Soap vs. detergent as wetting agent?
Natural soaps (e.g. Dr. Bronners liquid soap) which are made of natural biodegradable fatty acids are organic wetting agents to be used in organic gardens. Mixing a few drops with water before watering will help it penetrate the soil better. Biodegradable wetting agents available in the market often contain fulvic acid and seaweed extract as fertilizer.
Synthetic wetting agents, such as dishwashing liquids or detergents, are unsuitable for organic gardens as they usually are made using alcohol and petroleum derivatives, such as polyacrylamides, which are non-biodegradable. Also, they often contain chemical fragrances which can have a long-term impact on the soil.
1.2 Natural wetting agent
Aloe vera is a natural wetting agent because it contains saponins.
You can mix 1-2 oz of aloe vera juice or yucca extract per gallon of water.
One way to check whether a liquid is a wetting agent is to spread it on an oily surface. If the liquid contains a wetting agent, the oil would be dissolved and the surface tension of the liquid will be lowered, with the liquid spreading evenly along the surface instead of forming droplets on the surface.
1.3 DIY wetting agent
You can also make your own wetting agent at home using agar-agar powder, which is a natural gelatinous substance obtained from marine algae and seaweeds.
You can get the powder from health food stores or online. First, add boiling water to the agar powder to form a thick paste. Then take 1 cup (250 ml) of this paste and mix with 10 cups (4.5 liters) of water. You can then apply the mixture to any hydrophobic soil.
2. Sprinkle/drip watering technique
This method involves sprinkling small amounts of water on the soil at intervals, rather than putting a large amount of water in one go.
Doing it this way will prevent the water from running off. Instead, it will pool on the surface of the soil, and given time will infiltrate the soil.
This can be achieved by setting up a sprinkler system or a drip irrigation system to mimic a light, steady rain.
You’ll need to do this repeatedly (as much as 10 times, depending on the soil) till the soil becomes wet again. You can also
3. Mulching and covering
Mulching is the covering of the surface with straw, leaves or other organic matter. It can also be done by putting a plastic cover on top of the soil.
It is a preventive measure that reduces evaporation or prevents the soil from drying out completely, and so avoid hydrophobic conditions.
4. Tilling or mixing soil with water
Tilling wet soil is digging into the soil with a pitchfork, lifting it together with some soil and tuning it. It is a very important way to help revive dry soil.
For every 10 square feet (1 square meter) area of dry hydrophobic soil, pour 2 to 3 full large watering cans to wet the surface before tilling it.
For flower pots, mixing poor soil with water will help rewet dry soil.
Tilling or mixing the soil with water helps rewet dry soil by breaking the soil and mechanically combining water molecules with soil particles.
5. Mixing in organic matter
One of the best ways to fix hydrophobic soil is by working some organic matter into the soil to retain moisture for a longer period of time and to reintroduce microorganisms into the soil which will break down the waxy water repellant compounds.
Well-decomposed compost, for example, helps retain up to 100 times its own weight of water, and slowly releases moisture to plants as required. Other examples of organic matter can be in the form of compost tea.
However, simply adding compost to the soil would not beat hydrophobia. It must be combined with consistent input of moisture, either by irrigation or natural rainfall. Without consistent moisture, the compost will dry out and become hydrophobic.
This is the case when introducing new, dried compost purchased from the store for the first time. The dried compost must be pre-wet before putting it into the garden. Or, the dried compost must be gently mixed with the water and soil in the garden
Also, avoid using compost with unknown contents like municipal compost which may contain chemical pesticides and herbicides from grass clippings and other plants. Stick to homemade or locally available organic matter, and there should be no problems.
6. Wide-row and swale methods
The wide-row and swale methods are similar to the intermittent sprinkling technique discussed earlier. In both methods, water is allowed to stay on the surface of the soil until it eventually infiltrates.
The main difference is that the wide-row and swale methods allow for larger quantities of water to stay on the surface of the soil without running off. This is done by constructing wide rows with shallow indents in the middle to hold the water. Because the edges of the rows are raised, the water can’t run off and must remain in the indent till it infiltrates the soil. The process is repeated multiple times till the soil is rehydrated.
7. Bottom watering (for pots)
When potting soil becomes hydrophobic, any water applied to the soil will run down the sides of the container and go out through the holes at the bottom of the pot without being absorbed by the soil.
For that, you should water the plant from the bottom by placing the pot in a tray of water that rises to about one-fifth of the pot. The water will be absorbed up the pot through capillary action through the holes in the bottom of the pot.
The process can take one to 1-2 hour before the soil is completely wet again.
Bottom watering works especially well with succulents and cacti or plants that prefer a well-drained medium. Their growing substrate often becomes compacted and hydrophobic because they are often dried out between waterings.
8. Submerging the pot in water
If the pot is a small one you can put it into a tub full of water, holding it down so that it is completely submerged. Mix in some diluted liquid fertilizer to help the roots absorb some nutrients while the water works its way between the grains of the soil.
Watch for bubbles coming out of the submerged pot. That’s a sign that the soil is finally loosening and getting wet. Keep the pot underwater for 5 minutes or so, or until it stops bubbling.
This is especially an important step for transplanting plants newly purchased from the shop or nursery which can have very dry soil. Instead of taking the plant and its soil out of its pot and transferring it directly into the garden, submerge the whole pot in a water bath to wet it entirely before transplanting.
Hydrophobic soil is a problem that many gardeners have to deal with. When the soil refuses to get wet while the water collects in puddles at the surface, you need to fix the problem to save your plants.
For a short-term fix, you can buy or make your own organic wetting agents. For a long-term fix, you should try tilling the soil with water, mixing in organic matter, mulching, slow sprinkling or dripping watering technique to fix the problem.
For potted plants, you will need to try bottom watering or submerge the pot totally in water.
Try one or more of the fixes concurrently. It can take time and a lot of patience to see results, so don’t give up on your garden soil too quickly.
University of California, D. of A. and N. R. (n.d.). Watering hydrophobic soil. UC Master Gardeners of Santa Clara County.
Coleby-Williams, P. by J. (2021, April 21). Wetting agents – are you buying trouble?
Why water won’t infiltrate hydrophobic soils: ICL Specialty Fertilizers. Products and solutions for stronger plants, crops and grass. (2019, June 7).
Hayley, Says, C. H., Hayward, C., says, S., Sandra, says, C., Cecilia, says, K., & Kachi. (2020, November 15). Potting soil won’t absorb water. OSERA.