Water quality is one component of spraying that gets over looked time and again. Careful consideration is given to all other aspects of spraying like wind, nozzle size, and gallons per acre. Water quality and water treatment products are an opportunity for growers to maximize their crop input investments. Water is a key component when it comes to pesticide formulation. Approximately 90% of spray solution is made up of water. Many growers believe if the water runs clear it must be relatively pure. However, that is not the case. Water is an active chemical even without product added; because of this it can have negative effects on your pesticides. The mineral content, acidity/ alkalinity, and overall cleanliness (silt, debris etc) of your water, can play an integral part in the efficacy of your pesticide. Some ways water quality can affect how pesticides perform can be reduced solubility or decreased absorption by the target pest, all leading to a decrease in product performance.
Cavalier Agrow encourages growers to bring in a sample of spray water to get tested to check the suitability of the water. Some tests that are available include:
- pH and;
Turbidity refers to the suspended particles in the water. This can include clay, silt and fine organic matter. When glyphosate is sprayed with water that has high levels of these contaminants, the effectiveness of the product is decreased. To test turbidity you use a turbidity meter/sensor, or indirectly with a secchi disc/tube.
Water hardness is influenced by high levels of calcium and/or magnesium. When we discuss hardness we refer to a scale measured in ppm. Table 1 outlines the scale of water hardness. If you use hard water it can cause some pesticid
e solutions to precipitate out leading to plugged nozzles, and a decrease in product efficacy. Not only can it lead to precipitates but hard water can also effect the properties of surfactants, emulsifiers and wetting agents.
|Soft||100 – 300 ppm|
|Moderately Hard||300 – 750 ppm|
|Hard||750 – 1000 ppm|
|Extremely Hard||1000 + ppm|
Table 1: Water Hardness Scale
pH is another factor to consider when looking at spray water quality. pH is a scale used to describe the acidity/ alkalinity of a substance. The scale ranges from 1 to 14, 1 being very acidic, 7 is neutral, and 14 is very alkaline. pH’s greater than 8 (more on the alkaline side) can break down certain chemicals, in other cases alkaline solutions can increase pesticide efficacy. On the opposite end of the scale, acidic water can alter the physical properties of some pesticides and affect their stability.
An EC test measures the salinity of the water. The test uses electrical conduction to measure the soluble salts contained in sample. Using a conductivity meter to test the electrical conductivity (EC) of the spray water does not identify the ions present; it shows if a potential problem exists.
Figure 2: pH test done in Medstead, SK
There are products available to help combat some of these issues. Products like BB5, N-force and ModipHy are available and can be used in your spray solution. These products help neutralize free ions present in hard water, eliminating the potential of pesticides reacting with calcium, magnesium, iron and manganese. Talk to a Cavalier Agrow Business Agronomist about which product is the best fit for your farm. If you need to get your water tested bring in a sample to your Cavalier Agrow retail location close to your spray date and we would be happy to help. Poor water quality can adversely affect many spray jobs, particularly where products remain in the tank for extended periods, where high water rates are used, or where low rates of product are used. Know what your water quality is and how to treat it when using different products.