How Much AMS Does Your Spray Water Need?
Hard water is common issue for many water sources across the upper Midwest, Great Plains, and Canadian Prairies. It is why our homes have water softeners, why our well water tastes funny (or delicious), and one reason we need to add AMS (ammonium sulfate) or UAN to spray tanks to optimize weed control.
When we talk about conditioning “hard water” for herbicide applications, we are trying to prevent dissolved salts in water (e.g., calcium, magnesium, sodium, potassium, iron) from antagonizing, or binding, the pesticide in the sprayer tank. Dissolved salts bind to weak-acid, salt-formulated pesticides and reduce their efficacy (e.g., glyphosate [RoundUp], growth regulators, ACCase inhibitors [Select, Axial, etc.], ALS inhibitors [Pursuit, Express, etc.], HPPD inhibitors [Callisto etc.], and glufosinate [Liberty]).
A water conditioner like AMS helps prevent salts in spray water from binding to pesticides. AMS is most often recommended at rates from 8.5 to 17 lb/100 gal spray volume on herbicide labels. This is a wide window, and handling dry AMS can be a pain. So, how do you know how much AMS you should add to the tank to overcome the antagonism? A spray water analysis!
Example spray water report with suggested AMS rate calculation.
AGVISE Laboratories provides fast and convenient analysis of spray water used for pesticide applications. The Spray Water Analysis package includes calcium, magnesium, sodium, iron, pH, salt, hardness, and SAR (sodium adsorption ratio). The spray water report utilizes NDSU research and data to calculate the suggested amount of AMS required per 100 gallons of water to overcome antagonism. You will want to test each water source you use for pesticide applications.
Please give us a phone call at our offices in Benson, MN (320-843-4109), or Northwood, ND (701-587-6010), and we will send you a water sample kit. Each kit contains a water sample jar and a water sample submission sheet. Water sample tests are completed within a week and results are emailed to you, so you have information on your water source right away.
Don’t let salts take away from your weed control – get your spray water tested!