If you are grower, I am sure you are aware of the term surfactants. But, do you have any idea about this chemical? Check out how surfactants work in your grow room in our in depth, science based article.
Surfactants are organic compounds with an ‘amphiphilic’ property. The term ‘amphiphilic’ refers to the molecule; holding both hydrophobic and hydrophilic group. This configuration imparts surfactant with water insoluble component attached to a soluble one thus enabling it to reduce the surface tension of liquids.
Mechanism of action
The compound when applied at the interface of water and another surface, the hydrophilic part of surfactant gets attached to the surface of water; while the hydrophobic part shifts away and sticks to the opposite facade. Entire process acts to oppose the cohesive forces holding different water molecules together; thus modifying the surface. This mechanism facilitates the adhesive forces between water and another surface to take over and increase the bonding between these two surfaces. Total phenomenon works to keep the water molecules adhered to other material; thus increasing the wetness of that surface by water.
Surfactants that are used in agriculture and gardening methods are often categorized into following groups depending on the chemical nature and origin:
• Nonionic surfactants: It contains long chain of linear or non-phenol alcohol or fatty acids.
• Crop oil concentrates: These are mixes of petroleum based oils with surfactants.
• Nitrogen-surfactant blends: These are commonly used with herbicides; as they are premix of various forms of nonionic surfactants with ammonium sulfate or 28 percent nitrogen.
• Esterified seed oils: They are synthesized by fatty acids from seeds oils reacting with alcohol, thus forming esters in the process.
• Organo-silicone surfactants: They are the blends of silicone with nonionic or other surfactants.
Surfactants are often used in gardening to aid in moisturizing soil, so as to increase the movement of water through it. The normal watering process in soil is confronted with problems due to hydrophobic properties of the soil. Water may fail to attach to the soil surface due to the presence of hydrophobic elements like complex organic compounds.
Patches of dry soil can appear due to low infiltration process. The situation often arises in fine textured soil, as, the water may simply leach out due to gravity leaving dried soil behind.
Hydrophobic conditions are restricted to the top 1 inch of the soil; as the infiltration rate in these areas is 20 percent less than normal. Distress with soil drying out is aided by use of water repellent soil, non-uniform watering schedule, and gardening practices that degrade tilt and aggregation. Identification of water repellent soil can be carried out through laboratory tests; however it can also be confirmed by measuring the time water droplets take to penetrate the soil.
Surfactants are thus used to increase the infiltration rate of water in the soil. A surfactant can be applied as a concentrated solution or in the form of granular product. A solution is often applied for initial media wetting before the start of the cycle. Granular products are similarly used in case of long season crops, as these products have slow-release properties.
Plants are often sprayed with solutions intended to be taken up by the leaves. These solutions can be nutrient solution, supplements, herbicides or pesticides. However, every plant puts up a defense mechanism to prevent entry of foreign substance through leaves. A wax layer or cuticle forms a crucial part of this defense; as the hydrophobic property prevents entry, retention, and absorption of any solution.
The addition of a surfactant with that of any foliar feed optimizes the solution mixing, coverage, penetration and absorption through the cuticle. Any water based solution is thus retained better on leaves due to surfactant activity. Studies have shown the formation of unique ‘hydrophilic channels’ that initiate the transfer of polar molecule of any pesticide into the leaf tissue.
However, the solubility of a surfactant needs to be compatible to that of the foliar solution. Thus, the application of an appropriate surfactant depends upon the wax content and composition of leaves; a property often affected by the environmental condition.
Negative effects on plants
No harmful effects have been observed with application of a surfactant. However, a few studies involving ‘over the top’ application to the medium have shown a bit of toxicity.
Was this article helpful? Let us know your thoughts or contact us for more information.