Sometimes when soil is watered particles tend to float on top of the water. This does not mean that the soil is not good, it has become hydrophobic and with some simple treatments, the soil can return to a healthy state.
Floating soil indicates that it has become Hydrophobic. Soil floats mainly because of its inability to absorb the required amount of water. Well-aerated soil contains up to 10% air, and when water is added to dry, hydrophobic soil it forms a loose leachy mixture that is prone to floating.
Soil floating when watered or when rain falls is an uncommon occurrence that can be alarming at first.
Knowing what causes the occurrence and how to fix it is crucial in keeping healthy soil and healthy plants.
This article explains why soil floats when it’s watered and what you can do to fix the problem effectively.
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What Causes Soil To Float?
There are a handful of reasons behind soil to float. Here are a few of them:
- Potting soil contains peat moss. Under drought conditions, it gets dried. Then, it may make the soil float.
- If the potting soil is burnt or crusted or undergoing several environmental effects such as low humidity, direct sunlight, windy conditions, it may resist wetting.
- The soil gets severely dried as the water flows down
the sides of the pot instead of the root area.
This water-repellent state of soil is called Hydrophobia. Intense heating causes this state of the soil.
The properties of hydrophobic soil make it impossible for water to penetrate the soil and therefore cause problems in gardening.
Hydrophobicity in soils was first described by Schreiner and Shorey. They found that some soils in California could not be wetted and therefore were unsuitable for agriculture.
In hydrophobic soil, there remain certain organic molecules that are the byproduct of the decomposition of plant tissues and the activity of microorganisms.
These molecules resist water. This can be considered another reason for the floating of your potting soil.
Reasons For Soil To Becoming Hydrophobic and Floating:
The underground or lower profiles of Hydrophobic soil run bone dry. Here are the reasons why it repels water.
- The microbes break down the organic materials, waxy leaves, decomposed tissue, etc., and create a waxy layer that coats the particles in the soil.
This waxy substance hinders the absorption of water resulting in the hydrophobicity of soil.
- Sometimes the heavy percentage of clay in the soil makes it compact. The pores in the soil get clogged. That is why it acts as water-resistant.
Sandy soil is considered to be the most hydrophobic. It is free draining and well-aerated but unable to clench moisture.
NOTE: Soil can float or sink depending on how it is composed. Sinking soil might be sloped in the wrong direction, for instance.
Heavy soil containing a lot of clay might also sink due to its weight, while light soils containing lots of air or organic matter could float.
How To Water and Rehydrate Hydrophobic Soil?
A regular watering method is not anymore going to help when the soil is extremely withered.
The process of trickling or sprinkling water instead can also be applied. It will rehydrate the soil slowly, steadily, but surely.
You can follow two simple steps to rehydrate your hydrophobic soil. Here’s how it goes:
- If your pot is small or medium, immerse it in a bucket filled with lukewarm water. Initially, the pot may float.
It happens because there remains an excessive amount of air in the root ball. So, you have to hold the pot down.
After some time, air bubbles stop escaping and floating to the top, ensuring water has displaced the air in the soil. Now it is time to remove the pot from the water. - Again, If your pot is large, you can use a hosepipe that will trickle water on the soil.
To ensure that you are not overwatering, set a timer and follow it.
Another approach to watering hydrophobic soil that is prone to floating is by using alternative watering methods.
Bottom watering potted plants with hydrophobic soil is an effective way in increasing the soil moisture to an extent that it remains moist without the ill effects of overwatering.
We will explain how bottom watering works later in this article.
How To Fix Floating (Hydrophobic) Soil?
Hydrophobicity leads to both reduced infiltrations as well as water retention; the former results in wilting of plants while the latter causes root rot.
Death of the plant is the ultimate consequence. Hence, it is essential to find out ways to fix the problem.
To turn your potting soil into hydrophilic, you may follow the methods mentioned below.
1. Repotting
Repotting is a sure way in fixing the problem by replacing soil that has become defective by drying out to an extent that the soil becomes hydrophobic and floats.
When repotting, the chosen soil should contain adequate amounts of soil amendments such that it retains water for long enough without the expense of the soil losing aeration or drainage ability.
Using cost-effective amendments like dead leaves or old mulch into the soil when repotting can go a long way in getting the job done while at the same time boosting microbial activity within the soil.
Apart from leaves and old mulch, amendments like perlite and vermiculite also do a great job in soil moisture retention and aeration.
2. Bottom Watering
Bottom watering allows plants to absorb water from the bottom up through capillary movement throughout the soil when placed in a watering tray.
The plant is then removed from the tray after 15 to 20 minutes and the excess water is allowed to drain freely from the soil.
The soil remains moist for 3 to 4 days before it can be bottom watered again.
Bottom watering works by the soil’s ability to absorb water through upwards capillary movement.
A point to note is that not all soils will have the same rate of absorption.
The rate of absorption is dependent on the soil’s structure and the type and quantity of amendments in the soil.
3. Mulching Potted Soil
You may rely on the blanket of mulch made using shredded leaves, bark, newspaper, and other organic matters.
Lay the layer on the soil around your plant in a Donut-like structure. This layer holds a lot of water and keeps the soil humid and nutrient-rich for a long time.
It creates a microenvironment in your soil that promotes the happy, healthy growth of plants.
See our detailed post on mulching potted plants.
4. Misting Soil Regularly
To keep up the moisture level, you can make a schedule for misting plants and soil. Mist them properly for a few hours daily.
5. Using Surfactants
This method can be followed temporarily. Surfactants or wetting agents break the waxy coating and mitigate the surface tension.
In this way, they make the soil water absorbent and help the nutrients penetrate the soil. You can purchase a pre-made agent or make it at home from liquid dish wash, agar-agar, etc.
6. Amending the Soil
You can make specific changes to your soil. Remove 6-12 inches of soil from the upper surface and use fresh soil there.
Mix Perlite or Vermiculite with your potting soil to improve its texture. You can also loosen your hard and compacted soil using a fork.
7. Relocating the Plant
Relocate the pot to a shady zone. Heated and windy environments work as a catalyst for hydrophobicity.
So, consider relocating your plant pot to a shady area for preventing your soil from floating.
I use this Miracle-Gro Potting Mix from amazon, which ensures my plants stay healthy long after repotting. You can find it by clicking here.
This specially formulated blend of potting soil is designed to give your plants the perfect balance of nutrients, moisture, and aeration for vibrant plant growth.
Water Sitting on top of Soil
Another side effect of hydrophobic soil is water sitting on top of it.
Ever notice that some areas puddle up when it rains and some areas don’t? Or water just sits on top of soil in a potted plant and sometimes takes forever to soak in?
Well, the reason for this is that the soil was left unwatered for a long period of time, such that the soil has become hydrophobic.
The molecules between the soil particles draw close together when the moisture evaporates. This restricts the spaces or pores in the soil.
Now when the soil is water or when rainfall you will now see puddles of water just sitting on the surface which takes a while to be absorbed into the soil.
The Takeaway:
Soil floating in water is an uncommon occurrence that can be discovered by anyone with an interest in science. A number of reasons can make soil float or become hydrophobic.
Hydrophobic soil is water repellent. This means that when water hits the surface, it runs off of it instead of being absorbed. Hydrophobic soil is one of the most common problems for any lawn or garden.
