AMS Boosts Late Weed Control

With planting delays pushing back glyphosate applications, many growers will be treating bigger weeds, which are tougher to control. Water conditioners are a type of herbicide adjuvant that can boost performance, but how do you choose the best one?

Researchers say the ammonium sulfate (AMS) content is key.

Glyphosate and other herbicide labels recommend at least 8.5 pounds (lbs.) of actual ammonium sulfate for every 100 gallons of spray solution. Harder water or more difficult-to-control weeds may require up to 17 lbs. But many premixed water-conditioning adjuvants on the market today deliver less than half the minimum recommended rate.

According to Mark Bernards, weed specialist with University of Nebraska, these adjuvants just don’t have enough AMS to consistently improve weed control. In many cases, performance is no better than glyphosate alone.

In a recent University of Nebraska trial, two out of seven AMS alternatives were as effective as AMS when added to glyphosate for velvetleaf control. The other five resulted in weed control that was equal to — or lower than — weed control from glyphosate alone.

Likewise, the best velvetleaf control in a 2005 Kansas State University study came from glyphosate plus liquid AMS, followed closely by three adjuvants with high AMS content. The remaining six adjuvants had low or no AMS content and resulted in control roughly equal to or less than glyphosate alone.

Bernards says glufosinate has responded similarly to the addition of AMS and low-AMS substitutes.

The take-home seems simple enough: Make sure your herbicide adjuvant contains the minimum recommended rate of AMS. But according to Bernards, few aspects of glyphosate-based weed control systems have generated as much confusion as the role of AMS.

“Shortly after glyphosate was commercialized as Roundup herbicide, farmers and scientists recognized that its ability to kill weeds was reduced when it was mixed with hard water, which was typical for many of the areas where it was being used,” Bernards says.

The problem was antagonism. Negatively charged glyphosate ions bind to positively charged calcium, iron, and magnesium ions — three minerals commonly found in hard water.

“After many years of testing with many different materials, most researchers concluded that AMS was the most consistently effective and economical approach to overcoming hard water antagonism,” says Bernards. If you add enough ammonium sulfate to the spray tank, then the hard water ions (calcium, iron, and magnesium) precipitate from the solution as sulfate salts, and the glyphosate ions bind to the ammonium ions instead of the hard water minerals.

“It’s more commonly used as a nitrogen fertilizer, but all of a sudden ammonium sulfate got a lot of attention for improving weed control,” says Dean Collamer, agronomist with Honeywell. “The hitch was that many granular grades were designed for large-volume fertilizer application — not for dissolving in herbicide spray tanks.”

To alleviate handling problems, suppliers came out with a profusion of AMS pre-mixes made with less AMS and more alternative ingredients, like defoaming agents and surfactants.

“To make sure that you’re using the best adjuvant with your glyphosate spray, ask your supplier for formulations that deliver the minimum required dose of AMS,” advises Bernards. “Alternatively, you can apply a dry sprayable grade of ammonium sulfate directly to your tank.”

Collamer says adjuvant formulators now have access to grades of ammonium sulfate that are free of impurities, easier to dissolve, and more stable in solution. Honeywell, for example, produces Sulf-N PRO soluble ammonium sulfate specifically for liquid applications.

Leave a Reply

Herbicides Stories

glyphosate
Crop InputsWHO: Glyphosate ‘Unlikely’ To Cause Cancer
May 16, 2016
Via Reuters.com reporter Kate Kelland: The weed-killing pesticide glyphosate, made by Monsanto and widely used in agriculture and by gardeners, Read More
dicamba, Roundup Ready 2 Xtend
Crop InputsASA: No Dicamba On Roundup Ready 2 Xtend In 2016
May 16, 2016
While Roundup Ready 2 Xtend (RR2X) are tolerant to dicamba and glyphosate herbicides, no dicamba herbicides will be approved for Read More
CPP, glyphosate, dicamba, atrazine,
Crop InputsReport: Congress Pressing EPA On Glyphosate Review Handling
May 16, 2016
Via Reuters.com reporter P.J. Huffstutter: U.S. lawmakers have asked EPA to explain why it published – and then withdrew – Read More
Palmer amaranth in soybean stubble
HerbicidesWSSA: Billions In Potential Economic Losses From Uncontrolled Weeds
May 4, 2016
What losses would corn and soybean growers experience if they were forced to eliminate herbicides and other control techniques from Read More
Trending Articles
Food IT
Industry NewsCalifornia Event Will Mix Ag And Tech Professionals To Explore IT Solutions
June 20, 2016
Silicon Valley is hot on agriculture, and an upcoming event in California will bring together the food and tech industries Read More
Monsanto Luling Plant
Eric SfiligojWhat’s Next For Monsanto?
May 31, 2016
For the folks at Monsanto’s headquarters in St. Louis, MO, it has been an eventful few weeks. Back on May Read More
Soybean Plant closeup
Industry NewsMonsanto Rejects Bayer Bid; Open To More Talks
May 25, 2016
Monsanto Co, the world’s largest seed company, turned down Bayer AG’s $62 billion acquisition bid as “incomplete and financially inadequate” Read More
Eric SfiligojPity The Monsanto Haters
May 23, 2016
An old saying goes thus: “Be careful what you wish for. You just might get it.” Given current events, there Read More
Monsanto Luling Plant
Crop InputsReport: Bayer Eyeing Monsanto For Possible Mega-Merger
May 16, 2016
Bayer AG is exploring a potential bid for U.S. competitor Monsanto Co. in a deal that would create the world’s Read More
Aerial Drone
Precision AgA Deeper Dive Into The Future Of Precision Ag
May 9, 2016
For about two decades now, through the good and the bad times, the ups and the downs inherent in agriculture, Read More
Latest News
Eric SfiligojThe British Leave Vote Impact On EU Agriculture
June 27, 2016
Like virtually everyone else in the world this past week, I’ve watched the global reaction to Britain’s vote to exit Read More
Valent David Nothmann
Crop InputsValent Names David Nothmann Vice President Of Marketing
June 27, 2016
Valent U.S.A. Corp. has announced the appointment of David Nothmann as vice president of marketing. Nothmann will be responsible for Read More
The Andersons Waterloo
ManagementFirst Indiana Facility Certified Under 4R Nutrient Stew…
June 27, 2016
The 4R Nutrient Stewardship Certification Program has announced that The Andersons, Inc.’s Waterloo, IN, facility has been added to its Read More
CropLife 100BRANDT Contributes To Mayo Clinic
June 27, 2016
BRANDT, a leading agriculture retailer and manufacturer of specialty agriculture products, has pledged a sizable donation to the Mayo Clinic Read More
ManagementReport: U.S. Farmland Values On Average Continue Gradua…
June 27, 2016
Land price movement has been in the forefront for farmers, landowners, lenders and land brokers for a decade now during Read More
AdjuvantsPrecision Laboratories Introduces Intact Xtra For Use W…
June 27, 2016
Precision Laboratories announces the launch of Intact Xtra, an adjuvant designed for applicators who want to maximize spray applications and Read More
Key Cooperative’s new liquid fertilizer, crop chemical, and seed facility in Grinnell, IA stores 1.5 million gallons of liquid fertilizer and 120,000 gallons of crop chemicals.
Retail FacilitiesKey Cooperative Facility Features The Latest In Murray …
June 27, 2016
When Key Cooperative wanted to improve the overall efficiency at its new state-of-the-art facility in Grinnell, IA, it turned to Read More
Allen Summers Asmark Institute PSM Training
EmployeesAsmark Institute Sponsors 25 ResponsibleAg Auditor Trai…
June 21, 2016
The Asmark Institute has announced plans to provide 25 scholarships through their affiliated State fertilizer and agrichemical associations to help encourage Read More
Kennebec Elevator
CropLife 100Wheat Growers Celebrates Kennebec Elevator Grand Openin…
June 21, 2016
Over 250 patrons and guests were on hand to celebrate Wheat Growers’ Kennebec Elevator grand opening. South Dakota Secretary of Read More
Land O Lakes
Industry NewsLand O’Lakes To Acquire Ceres
June 20, 2016
Land O’ Lakes, Inc. and Ceres, Inc. have announced that they have signed a definitive merger agreement under which Land O’Lakes Read More
Food IT
Industry NewsCalifornia Event Will Mix Ag And Tech Professionals To …
June 20, 2016
Silicon Valley is hot on agriculture, and an upcoming event in California will bring together the food and tech industries Read More
LegislationVilsack Christens WinField Crop Adventure, Talks Monsan…
June 17, 2016
The WinField Crop Adventure grand opening ceremonies at Fair Oaks Farms (near Winemac, IN) welcomed USDA Secretary of Agriculture Tom Read More
Crop InputsFields of the Future: WinField Doubles Down with Agri-E…
June 16, 2016
Land O’Lakes, Inc., joined by Agriculture Secretary Tom Vilsack, today will host Fields of the Future, a live broadcast about Read More
Bayer sign
Crop InputsMonsanto Turns Back Bayer Again
June 14, 2016
Bayer AG’s bid to buy Monsanto Co. for more than $60 billion has hit an impasse that could pose a Read More
Young Corn Field
Crop NutritionNext Generation Of Nitrogen Efficiency Technology Conve…
June 13, 2016
Commodity price projections indicate farmers will continue to face tight margins again this year. Delivering higher yields and more bushels Read More
Industry NewsLa Crosse Seed Acquires Cover Crop Solutions Brand
June 10, 2016
La Crosse Seed announces that it is the new and exclusive owner of the entire family of brands of Cover Read More
ManagementTravel Plans and EU Rejection of Glyphosate, Biotech Cr…
June 9, 2016
Editors Paul Schrimpf and Eric Sfiligoj talk about upcoming trips and the latest in the European Union’s moves against glyphosate Read More