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How the Biggest Part of a Tank Mix Can Impact Application Efficacy

Precipitates in the tank mixture, insolubility of actives, nozzle gunk, corrosion… these are all issues that poor quality water can cause when used in a tank mix. As the largest component of a pesticide spray tank mix, water can significantly impact application quality. Hard water, the pH of the water, or contaminated water can all affect the efficacy of the tank mix. Water conditioners can help to mitigate these issues with herbicide or other pesticide tank mixes to achieve improved bio efficacy.

Hard Water

Water with high mineral content, known as “hard water,” is formed when water percolates through deposits of limestone, chalk, or gypsum, primarily made up of calcium and magnesium carbonates, bicarbonates, and sulfates. The dissolved magnesium, calcium, and other minerals form the hard water cations. These cations react with negatively charged pesticide molecules, reducing efficacy and/or affecting active ingredient solubility.

Hard water is formed when water percolates through deposits of limestone, chalk, or gypsum, primarily made up of calcium and magnesium carbonates, bicarbonates, and sulfates
Hard water is formed when water percolates through deposits of limestone, chalk, or gypsum, primarily made up of calcium and magnesium carbonates, bicarbonates, and sulfates

Water pH

Since different pesticides work best under varying pH ranges, it is important to consider the influence of the pH of the water when tank mixing pesticides. Tap water is often the most practical water source to be added to a pesticide tank mix. Generally coming from groundwater sources, the typical pH of tap water ranges between 6-8.5 depending on the soils and geology of the region.

Some water conditioners will lower the pH, while others will increase the pH. Adjusting the tank mix’s pH to the desired pH of the active helps to get the most out of a pesticide application.

Water Sediment

Sediment, algae, and other contaminants may interfere with active ingredients in a tank mix. This can cause filter and nozzle issues as well as reduce overall pesticide effectiveness. The negative impact of water sediment can be addressed to a certain extent by sequestering water conditioners. 

Water Conditioners

There are four categories of water conditioners: ammonium sulfate (AMS), acidulants, salts, and EDTA chelates. AMS and acidifiers both lower the pH of a tank mix. Salts such as potassium acetate, potassium carbonate, and sodium hydroxide raise the pH. These three categories are grouped as pH modifiers and can raise, lower, or buffer the pH of a tank mix. They can also affect a pesticide’s volatility, which is particularly important when dicamba-based pesticides are used.

pH modifiers

pH modifiers do double duty by complexing with the hard water cations preventing them from interfering with the negatively charged pesticide while modifying the pH.

Buffering agents

Buffering agents not only change the pH of a tank mix, but also hold that pH steady so that it is less likely to fluctuate.

EDTA chelates

The last category, EDTA chelates, does not affect the pH. They sequester undesirable particles or molecules that can negatively affect a tank mix. 

AMS-based Water Conditioners

AMS has unique dual functionality in a tank mix. The sulfate reacts with the hard water minerals in the water, and the ammonium helps transport the active ingredient into the plant. However, using traditional AMS is inconvenient because it is needed in large quantities and is difficult to dissolve, making it expensive to ship and handle. 

Fortunately, there are liquid AMS-based water conditioners that can also offer other beneficial water conditioning functionalities.

Multifunctionals: Water Conditioners with Bonus Features

Why use a separate water conditioner, surfactant, and other adjuvants when you can simply mix in one multifunctional with various adjuvant characteristics, all in one bottle?

With a built-in water conditioner, multifunctionals provide an excellent option for tank mixes that could benefit from both a water conditioner and other types of adjuvants.

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