Water constitutes up to 90% of most spray programmes. The variability in the quality of that water can cause a loss in spray efficacy.
Take hard water out of the equation to increase herbicide spray efficacy
Water constitutes up to 90% of most spray programmes. The variability in the quality of that water can cause a loss in spray efficacy.
David Lingan, UPL NZ Ltd’s Adjuvant Product Manager, says awareness of ‘hard’ water, and taking steps to ameliorate it, need to be factored into spraying throughout New Zealand to maximise ROI. “Never underestimate the impact of the type of water in a spray. What people forget is that water is actually a chemical (H20).
‘Hard’ water can have a negative impact on spray performance. David cautions that even seasonality (rising and lowering water tables between winter, spring, summer, and autumn) or using different bores on a single property can return a range of results for water hardness.
‘Hard’ water is defined as water high in mineral salts, such as calcium, iron, and magnesium. These can affect sprays’ potency. David says that’s particularly true with some widely used products including glyphosates, glufosinates, and phenoxies. He explains the positively charged cations in these minerals bind to negatively charged molecules. “This slows up-take, reduces solubility, and can precipitate out of the solution.
Simple test - big implications
On the positive side, he says testing for water hardness isn’t a big deal. “The easiest, fastest, and cheapest way is using swimming pool water test strips from your local hardware store.” David recommends all contractors and farmers carry a pack of strips in the truck. “You can’t tell if water is hard just by looking at it.”
Water hardness of 150 ppm is considered moderately hard and requires attention.
David recommends water conditioner and ion scavenger X-Change to optimise spray performance. X-Change acts as a “sacrificial” product changing hard water into soft by locking up free ions. As this reaction needs to occur prior to adding any herbicides, it is vital X-Change is added to the spray water first.
