Wetting agents are a category of surfactants that lower the tension of a liquid so hydrophobic soils can absorb water rather than repel it. When substrates are dry, as they often are with new plantings, or when there is inconsistent watering, a soil surfactant wetting agent will reduce the surface tension of the water.
All wetting agents are surfactants, but not all surfactants are wetting agents. Wetting agents are a class of surfactants that lower the interfacial tension of a liquid. An example is water. Water has a high interfacial tension, so a drop of water tends to “bead” on a hydrophobic surface, such as plastic.
Wetting agents are often pre-mixed into the potting media and fertilizers and function by reducing water's surface tension, enabling greater uniformity in moisture distribution. By doing so, the use of wetting agents results in greater root development, healthier and more uniform plants, and better water drainage.
The key difference between wetting agent and surfactant is that wetting agents can reduce the surface tension, allowing the liquid to spread drops to a surface, whereas surfactants can lower the surface tension between two substances. Wetting agents are a type of surfactants.
Surfactants are among the most widespread and commercially important chemicals. Private households as well as many industries use them in large quantities as detergents and cleaning agents, but also for example as emulsifiers, wetting agents, foaming agents, antistatic additives, or dispersants.
There are four main types of wetting agents: anionic, cationic, amphoteric, and nonionic. Anionic, cationic, and amphoteric wetting agents ionize when mixed with water.
You can make your own wetting agent using the same soap you use on your sponge, your hands and dishes.
If you need to substitute Cocamidopropyl Betaine (or another amphoteric) surfactant you will want to use a different amphoteric surfactant, and those can be hard to find. You can try coco betaine, babassuamidopropyl betaine, disodium lauroampho diacetate, and sodium cocoamphoacetate.
Humawet. Humawet is ideal for soil that is quickly losing water due to wind, runoff or drought. This soil surfactant is the most versatile, beneficial for many conditions. It is highly recommended when it's known you need water, oxygen and nutrient management in soil, but may be in doubt of which to use.
Surfactants are adjuvants that are added to the spray solution to help increase movement of the herbicide from the leaf surface to the interior of the cell. They are commonly used in postemergence herbicide applications on cereal crops.
Application and Safety
Unlike fertilisers that can cause toxicity if applied too frequently or in too large an amount, wetting agents present no such risk. While they won't cause in problems, applying them too frequently is a waste of money – once they have done their job there is nothing more that can be achieved.
It's also possible to use diluted dishwashing liquid or dishwater/laundry water as a soil wetter because the surfactants in the detergent break surface tension in water like wetting agents do. However, be cautious when using detergents in your garden and choose environmentally friendly/biodegradable options.
Conventional wetting agents are usually alcohol or petroleum distillates, such as polyacrylamides. Polyacrylamides are commonly used on an industrial scale in irrigation water to (in theory) improve the absorption of water by soils and to reduce soil erosion.
Nonionic surfactants tend to be the best at solubilizing oils, so they can take up some of the slack from anionic surfactants that don't do the best job at removing excess sebum from your hair. Nonionic surfactants also tend to be gentler, and can help mitigate anionic surfactants that can irritate sensitive skin.
ZHP WATER WETTER is a non-ionic surfactant and resin extender. It boosts the natural effectiveness of water – and delivers the dust control properties you need. With continued use, the resin extenders actually build up so you can further decrease your watering frequency.
In most domestic homeowner situations, the easiest and most accessible surfactant to use is dishwashing liquid. As mentioned earlier, soap contains the surfactant Sodium stearate. Liquid dishwashing liquid can be added to a tank mix of the herbicide or pesticide being applied and mixed with water.
A wetting agent is a surfactant that does something similar, except instead of helping the water lift out oily dirt, it is attracted to a solid surface, and forms a layer to change it so it doesn't repel water.
Dish soap isn't selective about removing oils and drying out cell membranes. It will dehydrate and kill the grass just as it would the nasty pests in your garden. So, yes, dish soap is not an entirely safe way to remove insects and lawn pests. With that said, soaps won't always kill your lawn altogether.
"Soap is a surfactant. Shampoo contains surfactant and detergents contain surfactants. Baking soda does not."
surface-active agent.
Jerry Coleby-Williams from Gardening Australia suggests making your own wetting agent from agar agar which is a seaweed product. Buy powdered kelp from a health food shop and slowly incorporate boiling water until you have a thick paste. Add 250ml of this paste to 4.5 litres of water and water this onto beds.*
Adding dish detergent to your weed killer could tear apart the molecular structure of the chemical, making it less effective in killing weeds. It is possible that adding a dish detergent to your weed killer as a surfactant could increase the adhesion of the chemical to the leaf of the weed.