Understanding The Different
Wetting Agent Chemistries
A surfactant is a wetting agent but a wetting agent may not be a surfactant. surprised?
BY STANLEY J. ZONTEK AND DR. STANLEY J. KOSTKA
W
etting agent: “Any compound
that causes a liquid to spread
more easily across or pene-
trate into the surface of a solid by
reducing the surface tension of the
liquid.”
Today’s golf course superintendent
has a dizzying array of wetting agent
products available to purchase. As a
general class of turf care products,
wetting agents are one of the more
frequently used on golf courses. Com-
mon sense would suggest that not
every surfactant or wetting agent is the
same. Ironically, all of our turf care
fungicides, herbicides, and insecticides
are organized into their own classifica
tions, i.e., the DMI fungicides, the
strobilurins, the phosphites, etc.
Wouldn’t it be nice if we could also
group wetting agents and surfactants
into the appropriate category of the
different chemistries from which they
are derived? That is the purpose of this
article. Diagnosing localized dry spot and hydrophobic dry patch in the field can be
Over the years, there has been a relatively straightforward, especially when noting dew patterns on the grass.
gradual change in the type of soils Where dew exists, there is good soil moisture. By contrast, only a few inches
used for golf course construction and away, there is no dew on the turf. It is time to test the areas using a soil probe.
maintenance. We have evolved from See next image. The grass is “talking to you.”
using the old, blended topsoils of years
ago (typical manufactured topsoils Areas without dew are powder
were 1-1-1 by volume mixes of sand, dry (on left) whereas samples
soil, and peat) to near straight sand taken in the adjacent area with
soils used today. Sandier soils are dew shows good soil moisture.
used for the construction of greens The powdery dry soil is
and tees and even sand capping of hydrophobic, or water repelling.
fairways. The same sandier soils are No amount of water will rewet
used for topdressing of these areas as the dry area. A wetting agent is
well. Sands have replaced soils. That’s needed, preferably in
the bottom line. Sandy soils tend to combination with some form of
naturally be, or become, hydrophobic surface aeration, to rewet the
(water repelling) in contrast to topsoils, soil, control turf wilt (and
which are less so inclined. decline), to save labor in hand
One of the most frequently asked watering, and to improve turf
questions of USGA Green Section appearance and playability.
agronomists is, “Which is the best
wetting agent product to use?” In a
Green Section Record Vol. 50 (15)
TGIF Record Number 208432 July 20, 2012 Page 1
(Left) Note the dew pattern on this wetting agent and soil surfactant test area. While a wetting agent is a surfactant, it only
wets. A surfactant can do more than just rewet the soil. (Right) Dry spots and uneven wetting can be a problem on any area of
the golf course, including greens, tees, roughs, and, in this case, a fairway. While all soil types can become hydrophobic,
sandier soils (which inherently hold less water anyway) seem to have the most severe problems. While there is a trend
towards “firm, dry, and fast,” there are situations where turf suffers permanent wilt. Turf loss is the result, especially when golf
carts drive through wilting grass. Wetting agents and soil surfactants can be used to rewet the area, allow for more even soil
wetting over time, and keep the problem from reoccurring in the future.
word, it “depends.” Specifically, it different modes of action in how they impact soil structure in fine-textured
depends upon what you want that interact with water and soil. This article native soils. In the agricultural chemical
product to accomplish. Is it to rewet will discuss the different classes of industry, these compounds are often
a dry, water-repelling soil as the result surfactant chemistries and their vary- used to aid in the dispersion of clays in
of isolated dry spot development? Is ing molecular structures. By defining flowable or suspension concentrate
it to prevent isolated dry spots from the capability of each class of surfac formulations. Sometimes referred to
developing in the first place? Is it to tant chemistry and defining which class as “old chemistries,” anionic wetting
make, “water wetter” as an injectable or classes of surfactant chemistry agents were introduced into the turf
material into your golf course’s irri each particular soil surfactant product care market in the 1950s.
gation system to try to move water contains, golf course superintendents Commercially available anionic
through the soil? Is it to improve irri- will better understand the best product blends include: AquaAid, Naiad,
gation efficiency and turf performance to use to address their particular Penterra, and Prevade.
using less water? Is it to use wetting management problem.
agents (rightly or wrongly) as a spray Note: This article is not intended to 2. Nonionic Surfactants.
adjuvant when applying herbicides, recommend one product over another. 2-1. Polyoxyethylene (POE)
insecticides, growth regulators, or All wetting agents/surfactants have Surfactants. A POE (also referred to
fungicides? Is it to improve rootzone specific uses. The goal is to provide as alkylphenol ethoxylate, or APE) are
placement of soil-directed pesticides information to better understand these also “old chemistry” wetting agents.
and fertilizers or to reduce their leach- products, which allows the end users, The original AquaGro contained a
ing? These are not easy questions to golf course superintendents, to decide POE. Like the anionic group of surfac
answer because, again, there are so which product best fits their needs. tants, POEs also can be phytotoxic to
many different wetting agent/soil
fine turf when used in some situations.
surfactant chemistries available to our SURFACTANT CHEMISTRIES POEs were originally developed to
industry. Note: While a wetting agent is In no special order of priority. correct localized dry areas, so they do
a surfactant, it only wets. A surfactant
help treat water repellency, but not
can do more than just wet a dry soil.
1. Anionic and Blends with nearly as well as newer chemistry
Anionics. Anionic wetting agents are wetting agents that were developed
SOIL SURFACTANTS - 101 negatively charged surfactants. They and introduced in the 1990s. This
Soil surfactant products are made with can offer fast wetting but, depending class of chemistry can enhance water
several different classes of surfactant upon application rate, can be phytotoxic movement into the soil. The original
chemistries. These classes of chem- to turf. Because of their negative ionic products in this category were intro-
istry have molecules with different charge, anionics can cause dispersion duced as turf management tools in
structures and therefore they have of clay particles, which can negatively 1954.
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July 20, 2012 Page 2
Commercially available POEs Hydro-Wet, LescoFlo Ultra, Remain, the characteristics of the respective
wetting agents include: APSA-80, and Sixteen90. Injectable formulations surfactant chemistries. Research con-
E-ZWet, FloThru, Injector, Lesco Wet, of Straight Block Co-Polymer wetting ducted by Aquatrols on the blended
Mizer, One Putt, PenMaxx, Surfside, agents include: Drench, Duplex, block co-polymer product Aqueduct
Water-in, and Wet-Sol. Fairway ISP, InfilTRx, IrriCure, showed that the blend was more effec-
Syringe, UniWet, and UniWet 25. tive in correcting localized dry spots
2-2. Block Co-Polymer Surfactants. Reverse Block Co-Polymers. Field and improving turf quality than either
This class of wetting agent chemistry observations show enhanced moisture the straight or reverse block co-
is the most commonly used in the turf retention in the rootzone, which can be polymer used alone. To date, this
care market today. These compounds particularly helpful in soils that do not blend remains the standard by which
are significantly safer to fine turf than hold much water. Some companies all experimental formulations are
POEs and are very effective in reduc have referred to the compounds as compared in Aquatrols internal
ing soil water repellency and improving “retention-type surfactants.” These research.
soil water content and plant-available materials were introduced into our Commercially available products
water. Two basic chemical structures industry in 1995. based on blends of these two block
are used: Commercially available reverse co-polymer categories include:
Straight Block Co-Polymers. Field block co-polymers include: Primer Aqueduct, Resurge, and ReWet.
observations show enhanced water Select, Magnus, ReLoad, Rely II, Note: “Field blends” of different wet-
movement in the soil and can be Respond 3, Retain, TriCure AD, ting agent chemistries are becoming
helpful in leaching programs. and TriCure Micro. more commonly used. That is, two or
Commercially available straight Blends of Straight and Reverse more wetting agents/soil surfactants
block co-polymers include: Brilliance, Block Co-Polymers. Industry scientists are tankmixed to try to achieve rewet-
Capacity, Cascade Plus, Conduit 90, have attempted to find ways to exploit ting, retention, and moving excess
A wilt and dew pattern on a sand-based tee. With sandier soils, water management always is a challenge, especially during
hot and dry weather.
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“Firm, dry, and fast” conditions are good for golf, but it is a challenge for the golf course superintendent to find ways to use
water as efficiently and effectively as possible while avoiding excessive dryness, which can damage the turf, especially under
cart traffic, as this image clearly shows. Wetting agents and soil surfactants can be important management tools to achieve
this goal, whether they are sprayed onto the turf or injected into irrigation systems.
water through the soil profile. Such blend of wetting agent chemistries standard and reverse block co-polymer.
blends are typically recommended by improves water penetration rates Tournament-Ready imparts multiple
company technical advisors. through the soil compared to straight modes of action by making use of
block co-polymer products. These three different types of surfactants.
2-3. Alkyl Polyglucoside Surfactants materials seem to improve water
are made from a sugar molecule availability in the rootzone for better 2-4. Modified Methyl Capped Block
reacted with a fatty acid and are con- growing conditions and enhanced Co-Polymer. This class of wetting
sidered naturally derived surfactants irrigation efficiency. Independent agent is a patented variation of the
(but not to be confused with organic). university research has demonstrated block co-polymer class. The structure
Like many surfactants, alkyl polygluco- that treatment resulted in improved of the molecule was modified by
sides can reduce soil water repellency. plant-available water and turf quality replacing -OH terminal groups with
However, when blended with a block even when irrigation inputs were -CH3 (methyl) caps. This small change
co-polymer surfactant, these formula- reduced to less than 50% evapotranspi- in molecule structure modified the
tions have been shown to increase ration (ET) replacement. This chemistry hydophilicity of the terminal groups.
infiltration more than either wetting was introduced in 2000. The -OH groups are hydrophilic, or
agent component alone. This phenome- Commercially available alkyl poly- water loving, while the CH3 (methyl
non of synergistic surfactant wetting glucoside and straight block co-poly- groups) are hydrophobic, or water
activity, the first such activity reported mers include: Dispatch Injectable, repelling. As a result, the methyl
for soil wetting agents, has resulted in Dispatch Sprayable, and Tournament- groups impart a small hydrophobic
patents being granted on this tech- Ready. Note: Tournament-Ready con- characteristic to the terminal groups.
nology in the U.S. and globally. This tains a blend of alkyl polyglucoside, This modification changes how the
Green Section Record Vol. 50 (15)
July 20, 2012 Page 4
surfactant attaches with the hydro- issues, through the soil profile, where positively charged molecule, they
phobic coatings that cause water they may be beneficial to moisture tightly bind to soil particles and have
repellency. This results in thinner, more control. been reported to cause treated soils to
continuous films of water around soil Examples of these compounds are become more water repellent when
particles and surfaces of organic found in the OARS® product line. used repeatedly. To the best of our
matter, which balances air-to-water knowledge, no cationic surfactants are
ratios in the soil for (hopefully) a better 2-6. Multibranched Regenerating sold as soil wetting agents in our
growing environment in the soil. Field Wetting Agents. These molecules industry.
testing has demonstrated a diversity of differ from the traditional linear co-
benefits in soil water availability, turf polymer molecules in that they are 4. New Chemistries. There will no
performance, and turf stress tolerance. much higher in molecular weight and doubt be new wetting agents/surfac
This chemistry, granted patents in the have multiple interactive sites, such tants and blends available to our
U.S. and globally, was introduced into that each branch is essentially a wet- industry in the future. The ability to
our industry in 2004. ting agent in itself. Branching, coupled modify and manage water more effi-
The sole commercially available with higher molecule weight, not only ciently and more effectively continues
modified methyl capped block co- increases the interaction between the to be a long-term goal. Equally, new
polymer wetting agent is sold under wetting agent and the soil, but also products will no doubt be developed
the brand name Revolution. affects the biodegradation profile. As that will allow for more even wetting of
one branch is removed via biodegrada- the soil and more efficient use of water
2-5. Humic Substance Redistribu- tion, a new lower molecular weight in that soil, while better managing
tion Molecules. This class of wetting surface active species is regenerated ongoing problems with fairy rings,
aids was patented by Milliken & Co. to continue to manage the water in the isolated dry spots, and poor soils.
and introduced to the turf industry by soil profile.The use of these molecules Stay current.
Aqua-Aid in 2003. These molecules on turfgrass was patented in 2005 by
allow water penetration through the Milliken & Co. Examples of these MANAGEMENT
soil profile by disrupting the hydro- compounds are found in PBS-150® One major management topic not
phobic supramolecular humic associ and the OARS® product line. discussed in this article has been how
ations, most prevalent in the top one to wetting agents and soil surfactants are
two centimeters (0.40 to 0.80 of an 3. Cationic Surfactants. This group managed and used. Oftentimes, these
inch) of the soil, which led to localized of surfactants is not commonly used products are added as spray adjuvants,
dry spots. Reduction in size of the as soil wetting agents due to their “just because.” This creates a whole
large hydrophobic associations into strong biocidal activity. Many of these new set of interactions that are difficult
smaller, more soluble conformations compounds are effective disinfectants to measure. For instance, does a little
results in increased water penetration and may be particularly aggressive to extra wetting agent in the tank aid in
and allows for redistribution of these plant tissues, resulting in severe plant fungicide placement or compromise
“smaller compounds” from the surface, damage when applied at rates effective fungicide effectiveness? These are all
where they cause water management for water repellency mitigation. As a good topics to discuss with your com-
(Left) Turf loss due to localized dry spots, or LDS. The solution is a wetting agent or soil surfactant program that allows the
grass to recover and to keep the problem from reoccurring in the future. See next image. (Right) Complete recovery. LDS has
not reoccurred due to adjustments in the way the turf is managed using wetting agents and soil surfactants.
Green Section Record Vol. 50 (15)
July 20, 2012 Page 5
pany technical representative, supplier, not mentioned, if a product is mis-
and USGA agronomists. categorized, or if a product is no longer
How best to manage irrigation is available. At least the superintendent
another important management topic. will know which question to ask the
Specifically, if your goal is to rewet a next time a representative tries to sell
dry, hydrophobic soil, it is best to a wetting agent or surfactant. You can
prepare the area with some form of ask, “Is it a straight or reverse block
surface aeration, pre-wet the area, co-polymer? A modified methyl
apply the wetting agent or soil capped co-polymer? An APE or a
surfactant, and water it into the soil POE? By the way, are your wetting
profile. For maximum efficiency and agents anionic or cationic?”
effectiveness in this case, it is best not
to let the wetting agent dry. Rather, STANLEY J. KOSTKA is Director of
water it in rapidly and liberally. The Technology and Business Develop
addition of other products could there- ment for Aquatrols Corporation of
fore compromise the action of those A stylized view of what a branched America. He has spent nearly 20 years
materials either by too much water or wetting agent molecule looks like. working in the area of understanding
compromise the wetting agent/surfac- Surprised? There is a whole lot more how surfactants can be used to man-
tant product by not using enough to selecting a wetting agent or age soil water repellency and improve
water. Again, when in doubt, ask for surfactant than the average person water use and productivity in turfgrass,
advice. might know. It is a complicated ornamentals, and agricultural crops.
In preparing this article, almost science. (Image courtesy of He holds 13 patents relating to novel
every contributor made the following Milliken & Co.) surfactant technologies and agri-
point: With the wetting agent options chemical formulations. Stan received
we have today, you either treat the information from technical representa his Ph.D. in plant pathology from the
water or treat the soil. There are tives of the companies who formulate, University of Massachusetts, an M.S.
different wetting agent chemistries to develop, produce, and sell wetting in plant science from the University of
solve whatever problem you may have. agents and soil surfactants. This Connecticut, and a B.A. in biology
Also, the wetting agents and soil information (hopefully) allows all of us from the College of the Holy Cross
surfactants available today are much to make informed decisions on which (Mass.).
more sophisticated than the products wetting agent chemistry helps solve
used years ago. In the “good old days” the problems you have, as it pertains RANDY D. PETREA, reviewing author,
of turfgrass management, we used to to soil water repellency, enhanced soil is a senior chemist at Milliken Chemical
add a quart of wetting agents to every moisture retention (or not), the preven- with over 23 years of experience in
spray tank. We have come a long way tion of isolated dry spots, or the treat- surfactant design, synthesis, and for-
since then. ment of dry patch and fairy ring once mulation of new products for various
Wetting agent and soil surfactant they develop. One key thing to remem- industry segments. He holds 10
products are used in many ways and ber is to ask your sales representative patents, six of which relate to the use
for many different reasons on golf for research reports on field evaluations of novel soil surfactants for moisture
courses today. It is important to think of the product. That third-party con- management. He received an M.S. in
about what you are trying to accomplish firmatory testing is the only way to analytical chemistry from the Univer-
when applying any turf care products, ensure you can count on a product sity of Tennessee - Knoxville and a
including wetting agents and soil sur- to do what is claimed. B.S. in chemistry from Pfeiffer College
factants. READ THE LABEL. If your In summary, there are many (N.C.). We thank Randy for his input.
questions are not answered, contact different wetting agent and surfactant
the company. It is a call or email worth compounds and chemistries available. STANLEY J. ZONTEK is the director of
making to ensure the product you are Hopefully, by knowing some of the the USGA’s Mid-Atlantic Region. He
using is being properly applied. strengths and weaknesses of the formerly served as director of the
various commercially available North-Central and Northeastern
FINAL THOUGHTS products, the right choice can be made Regions during his tenure with the
Still awake? As you can see, this by you, the consumer, on which USGA Green Section. Stanley joined
article is technical in nature. Most of us product to purchase and use. the Green Section in February 1971
are not chemists. We rely on research and is a graduate of Penn State
results from our state universities DISCLAIMER University. He is the USGA’s longest
along with field trials of side-by-side All the information contained in this tenured employee. He is old enough to
product comparisons, testimonials from article comes from the best possible remember the earliest wetting agent
fellow golf course superintendents who knowledge available at the time of chemistries, which are no longer
have used these products, and product writing. We apologize if a product was available!
Green Section Record Vol. 50 (15)
July 20, 2012 Page 6
