Getting the Most Out of Your Summer Sprays by Using Quality Spraying Water

Anthony Stibbard

Dec 09, 2021

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The recent announcement by the Bureau of Meteorology that a La Niña weather pattern has developed in the tropical Pacific is likely to be short lived in meteorological terms but persisting into late summer or early autumn.

This weather pattern will result in above average rainfall across northern and eastern Australia during summer. Higher chances of rainfall events, coupled with global chemical supply shortages, which have resulted in price increases means growers need to plan ahead to maximise their chemical applications this summer.

Using quality water when spraying is important to get the most out of your chemical and in turn getting better results on the ground. 

Summer fallow spraying in Australia comes with its challenges as is. Adverse conditions, wind and other elements all affect the quality of results. Water quality can also drastically affect the efficacy of certain herbicides.

Water testing is important to understand the key elements (pH, Hardness, Turbidity and Salinity) which may be resulting in a reduction in efficacy.  

Water pH

Water pH is the measure of acidity or alkalinity of your water and is measured on a scale of 1 (highly acidic) to 14 (highly alkaline).

Bore water in Australia tends to be alkaline and this can result in issues when being used in a spray solution. Certain herbicides, when added to alkaline water can dissociate in solution resulting in less active ingredient being available in the spray solution, and in turn reducing the effectiveness of your application.

It is advisable to understand the pH of your water and then if required a buffering agent such as Tebuf 700 can be added to water to reduce the pH.

Buffering agents work by reducing the pH to a certain point but will not continue acidifying your solution if more is added. Other straight acid products will continue to acidify your solution the more you add. 

Water Hardness

Bore water in Australia often has a high content of Magnesium, Calcium and bicarbonates. These cations and bicarbonates present in the water can bind to certain active ingredients in solutions, which reduces the effectiveness of your spray.

Glyphosate and 2,4-D Amine are 2 commonly used herbicides which will have reduced effectiveness if used in water with a high concentration of cations or bicarbonates.

Ammonium sulphate can be used to reduce the hardness of water and improve the effectiveness of your spray solution. The standard rate for spray grade AMS is 800g/100L but it is strongly advised to get a water test done, to assess the overall hardness in order to adjust the rate as required. 

Turbid Water

Dirty water can also affect the quality of your spray solution. Certain products such as Paraquat binds tightly to clay molecules in the solution and will reduce the overall effectiveness of your spray application.

Spraying with dam water is usually not advised but is required in some instances. Choosing the right products to use with dirty water is important and the addition of additives such as Alum can also be used to purify your water.  


Salt in solution is very common in bore water around Australia. High saline levels can also result in some herbicides dropping out of solution, a reduction in spray effectiveness.

Diluting the saline water with rainwater can help to reduce the salinity. A test to understand the overall salinity in your water is important to determine suitability for spraying. 

Water testing is strongly advised in order to get the most out of your herbicides and improve the quality of your summer fallow sprays.

If you are looking for more information on where to access water tests get in contact with your local Department of Agriculture representative.

Water test strips are also available for purchase, these test strips can be used in the field and give a good indication of pH and hardness. 

To find out more about products available to help your summer fallow spraying, please visit


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Anthony Stibbard

Dec 09, 2021

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