The pH of Water & why it matters

Everyone’s water source is different. Whether it is rainwater, mains or borehole, its pH level and hardness can greatly affect the efficiency of certain products. These products represent a significant investment, and it’s possible to lose their effectiveness if conditions are not right. So, it is essential to understand the risk factors associated with the products you’re using and to test and adjust your water quality before filling your sprayer.
Some active ingredients in pesticides break down rapidly in alkaline water, while others are unaffected or degrade more slowly. When active ingredients degrade, their absorption by the plant is reduced, leading to decreased efficacy and increased costs. pH measures the acidity or alkalinity of a solution and is determined by the balance between hydrogen (H) ions and hydroxyl (OH) ions. “pH” stands for “potential for hydrogen” and reflects the concentration of hydrogen ions in water. When the concentration of H and OH ions is equal, the solution is neutral. pH is measured on a scale from 1 to 14, with 7 being neutral. Water with a pH below 7 is considered acidic, while a pH above 7 indicates alkalinity. The pH scale is logarithmic, meaning that a pH of 4 is ten times more acidic than a pH of 5.

High pH, or alkaline water, can cause some agrochemicals to break down through alkaline hydrolysis. Once a
pesticide degrades, it can no longer perform its intended function. The more alkaline the water, the quicker
this breakdown occurs. When water pH exceeds 8 or 9, hydrolysis happens at a much faster rate, with every
unit increase in pH accelerating the process tenfold. Some pesticides begin to degrade the moment they are mixed with high-pH water. The longer the mixture remains in the tank before spraying, the more significant the breakdown. For this reason, it’s essential to be aware of whether any agrochemicals you’re using are susceptible to alkaline hydrolysis or the pH of the water you’re using, and how to address any issues.

Several pesticides commonly used in crop treatments are at risk of degradation in alkaline conditions, including:

• Pyrethroids
• Certain plant growth regulators (PGRs) and fungicides
•  Some herbicides, such as glyphosate

Glyphosate, for instance, is most stable at a pH of 5, meaning most water sources will require treatment with a water conditioner or citric acid to acidify the water before adding glyphosate to the spray tank. You can check the pH of your mixes with a simple pH tester or ask your regional Aiva rep to pop in with their farm kit.