Tank mixing is a convenient way to deliver multiple products to the area you’re treating. It can allow you to apply herbicide, fungicide and insecticide products all in one pass, or to add adjuvants to a product to enhance application. Combining products also lets you do fewer passes, saving resources like time, labor and fuel. You should always follow the product label for tank-mixing instructions, but here are a few guidelines for an effective tank mix.
If you’ve ever opened your spray tank to find a gunky mess, or encountered particulate at the bottom of your tank, you know how easily a tank mix can go wrong. Tank-mix errors are more than inconvenient or messy. An improper tank mix can result in application of an incorrect use rate of your active ingredients, wasting both product and resources. In this article, we’ll look at some of the basics of formulations and how to ensure a proper tank mix.
Formulation basics
A formulation is simply a way to deliver an active ingredient to a specific target site in a usable form. Agricultural products are delivered in one of these common formulation types:
Liquid formulations
Soluble liquids (SL): In SLs, the active ingredient is completely soluble in water in its undiluted state. Once diluted in water, it forms a clear solution.
Emulsifiable concentrates (EC): ECs involve active ingredients dissolved in solvent with an added surfactant. When added to water, the formulation is dispersed as small, emulsified oil droplets. The surfactant enables the oil-based component to mix with water.
Suspension concentrates (SC): SCs are formulated with gels which prevent sedimentation of active ingredient particles during storage. SCs have low water solubility. The active ingredient is dispersed in water as small particles which remain suspended for application.
Solid formulations
Wettable powders (WP): In WPs, the active ingredient is combined with an inert solid ingredient, such as clay. These powder-like formulations form a suspension and usually require regular agitation to prevent precipitation.
Water-dispersible granules (WDG or WG): When a WG formulation is added to water, the granules break apart to form a suspension. If surfactants are added to a tank mix with a WG product, they will prevent the granules from breaking apart in the water.
Tank mixing is a convenient way to deliver multiple products to the area you’re treating. It can allow you to apply herbicide, fungicide and insecticide products all in one pass, or to add adjuvants to a product to enhance application. Combining products also lets you do fewer passes, saving resources like time, labor and fuel. You should always follow the product label for tank-mixing instructions, but here are a few guidelines for an effective tank mix.
Note the initial water volume in the application tank
Starting off with too little water can cause precipitation. About 50% of the final tank volume should be water. Pay attention to total water volume, which will be described on the label as GPA (gallons per acre) or L/ha (liters per hectare). As total water volume decreases, the chance of incompatibility of tank-mixed ingredients increases.
Follow the proper order and rate of addition for crop protection products
Mixing order is extremely important for proper dispersal. Below is the recommended order for addition of products, allowing for complete mixing/dispersal between additions. However, remember to always consult product labels for order of addition compatibility. Do not add products simultaneously.
Water, which may be the tank’s initial water volume
Water-soluble packets
Dry formulation types, such as wettable powders or water-dispersible granules
Water conditioners, such as AMS or AMS solutions
Heterogeneous liquid formulation types, such as suspension concentrates; heterogeneous liquids will be opaque when added to water
Homogeneous liquid formulation types, such as emulsifiable concentrates or soluble liquids; homogeneous liquids are clear when added to water
Micronutrients
Remaining water, to make up 50% of the total tank volume
In the example on the left, products were added in the incorrect order, resulting in a chunky mixture likely to clog equipment and result in uneven or ineffective application. In the example on the right, the same products were added in proper order and allowed to fully disperse between each addition, creating a uniform mixture.
Note temperatures of products and water
Temperature of liquid products affects their ability to be pumped into application equipment, while water temperature can affect dispersion. Dry formulations may take longer to disperse if cold water is used for dilution. Make sure heterogeneous liquid formulations are agitated well before adding them to cold water.
Pay attention to water quality
Water hardness and pH can also affect proper mixing. Make sure you know the pH of your water source. If you change water sources, it’s a good idea to test your water quality. The pH is very important to product activity and stability. Most products work best at a pH of 6–7, however, some products may work better at a lower pH or could be degraded at a higher pH. Always check the product label for pH recommendations.
Jar testing
If you’re trying out a new tank mixture, working with a product that can be difficult to handle or simply have doubts about the mix you’re about to perform, do a jar test first. This acts as a scaled-down version of what you’ll be doing in your tank. Combine ingredients in the proper proportions and order in a quart jar and see how well everything incorporates. This is a good practice for safety, efficiency and avoiding a mess in your application equipment. You can also reach out to your Corteva Agriscience representative with tank-mixing questions. They can help connect you to technical resources, including advice on whether you can fix a tank mix that has gone awry.
To learn more about tank-mixing procedures, check out the full video of our Formulations 101 training session below. The Purdue University Extension also offers an excellent guide here.
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