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Here’s another “high tech” blog post.  Like my last blog post, this topic may be out of reach for the standard turfgrass warrior.  But hey, if you’ve read my blog posts from the beginning, you will see we are past the 100 or 200 level courses.  We are now in advanced studies!  As I’ve said before, I think it is good to know about some of the many issues out there when it comes to turf care and maintenance.  You can never know too much!

In this post, I’m going to discuss soils that are resistant to water.  Soils that are difficult to “wet” (wet – used as a verb in this case) are branded as hydrophobic soils.  The soil repels water.  The soil is difficult to wet because it resists penetration by water.  The infiltration of water into this type of soil can often be enhanced by applying a non-ionic surfactant, more commonly called a wetting agent.  Wetting agents are detergent-like substances that reduce the surface tension of water, allowing it to infiltrate and wet the soil more easily.  Soap is one of the most common surfactants.  And a “SURFace ACTive AgeNT” causes change to the soil at the surface.

Understanding how wetting agents work will give you a better idea of the situations for which they are best suited.  There are three “forces” that act upon the movement of water into the soil.  The first is gravity.  Gravity is a constant force that pulls the water downward.  The second force is cohesion, the attraction of water molecules to each other.  Cohesion is the force that holds a droplet of water together.  It creates the surface tension, which causes the droplet to behave as if a thin, flexible film is covering it, keeping the water molecules apart from other substances.  The third force is adhesion, the attraction of water molecules to other materials.  This force causes water molecules to adhere to other objects, such as soil particles.

The chemist on my staff, Jake, says I should mention that the forces discussed above are actually electromagnetic forces.  And, Jake says I should be more precise by explaining the properties of cohesion and adhesion, specifically detailing hydrogen bonding and capillary action.  Okay, Jake looks at everything down to its molecular structure.  If he gets real excited, he’ll start seeing atomic valences.  That’s what chemists do.  That’s why I engage the best minds in the business to ensure you have flawless analysis.

Hydrogen bonds form between the hydrogen of one water molecule and the oxygen of the neighboring water molecule.  In ice, all the molecules of water are held in their places by a network of hydrogen bonds.  In water, only some molecules at any given time will be attached, in a constantly changing process.  The hydrogen bonds have to be broken in order for ice to melt, and more for water to become steam, and because this takes a lot of energy we see a higher than expected melting and boiling point.

Capillary action is caused by the water molecules pulling one another along via the hydrogen bonds.  Surface tension is caused by the water molecules on the surface holding onto one another in a network, like giving enough support for a small bug to walk on the surface.  If the bonds within a liquid are strong enough, then the liquid will have a large surface tension.  Since hydrogen bonds are one of the strongest intermolecular forces known (apart from covalent and ionic bonds) liquids with large surface tensions tend to have hydrogen bonds.

With regard to capillary action, there are two forces (Watch Jake tell me it is an electromagnetic force.) acting on a molecule of the liquid: an attractive force exerted by other liquid molecules, and another attractive force exerted by the walls of the capillary.  (A capillary is like a small tube or straw inserted in the water.)  Hydrogen bonds are an example of the attractive forces that can be exerted by the liquid molecules (e.g. between water molecules, or between ethanol molecules), or the attractive forces that can be exerted by the capillary walls.

By considering the strength of the hydrogen bonds between the molecules in a liquid and the strength of the attractive forces between the capillary wall and the liquid molecules, one can determine whether capillary action can take place with the liquid being observed. 

The effects of these forces can also be simply illustrated by placing a drop of water on a paper towel and another drop on a piece of wax paper.  On the paper towel, the force of adhesion between the water molecules and the paper molecules is greater than the force of cohesion that holds the water molecules together.  Therefore, the water droplet spreads out and soaks into the paper towel.  On the wax paper, the water "beads up" - that is, the droplet remains intact.  The water molecules are not attracted to the wax that coats the paper's surface.  Instead, the water molecules stick to each other.  When the adhesive forces between water molecules and an object are weaker than the cohesive forces between water molecules, the surface repels water and is said to be hydrophobic.

Most wetting agents have polar and non-polar distinctiveness.  These characteristics allow the water to cling to, or even soak into certain organic matter.  In hydrophobic soils, the soil particles are coated with substances that repel water, much like the wax coating on leaves.  In studies of localized dry spots in turfgrass, the soil particles were found to be coated with a complex organic, acidic material that appeared to be similar to the mycelium of a fungus.  My blog post “Turfgrass Diseases” discusses funguses a little.

Nearly all of the soil wetting agents used in turfgrass management are non-ionic surfactants.  Non-ionic surfactants, or surface active wetting agents, decrease the surface tension of water, allowing the water molecules to spread out.  When applied to water-repellent soils in high concentrations, surfactants can improve the ability of the water to penetrate the soil surface and thus increase the permeation rate.  Remember, I’m talking about water penetrating soil, not water penetrating the surface of leaves on plants.

Hydrophobic soils can cause problems on golf courses, playing fields and other turf areas.  Water repellant soils can also be found in gardens, shrub beds, nurseries, greenhouses, and in open fields.

Golf course greens keepers commonly report troubles with localized dry spots on their greens.  Nursery operators sometimes encounter hard-to-wet soil in pots and greenhouse beds.  And, some farmers who work soils high in organic matter complain that the soil wets too slowly, reducing crop output.  Problems with hydrophobic soils are also commonly associated with citrus production areas down south.  In some locations where mine wastes have been deposited, and with burned-over forestland and grassland, there tends to be hydrophobic soils.

If water cannot readily enter and wet the soil, the availability of moisture to plants is reduced, decreasing the germination rate of seeds, the emergence of seedlings, and the survival and productivity of plants.  Lack of water penetration in the soil also reduces the availability of essential nutrients to plants, further limiting growth, health and productivity.  In addition, water that cannot penetrate the soil can run off the surface and increase erosion.  Water repellency often occurs in localized areas.  As a consequence, the soil wets inconsistently and dry spots occur.

In the majority of situations, low water penetration rates are caused by factors other than water repellency.  Water naturally moves more slowly into fine-textured (clay) soils because the spaces between the soil particles are just too small to allow rapid water movement.  Cultural practices that promote good soil tilth and particle aggregation can improve the infiltration rate on these soils.  On the other hand, activities that lessen soil tilth and aggregation make problems worse.  Tillage pans (an induced layer of soil which has high bulk density – see my blog post on “High Traffic Areas”) and compaction by personnel and/or machinery also reduce infiltration.  In these circumstances, wetting agents will have little or no effect.  Remember what I’ve said about soil compaction.  There’s not much you can do about it except physically manipulate the soil.  There’s nothing you can dump out of a bag or a jug that can reverse soil compaction.

How effective are these wetting agents?  Research has been conducted on hydrophobic soils and on the effectiveness of wetting agents.  Some of these studies have focused on localized dry spots in turf grown on naturally sandy soils and on formulated materials high in sand content.  As one would expect, these dry spots become a grave turf management dilemma during the summer months, especially during periods of drought.  In spite of frequent irrigation, the soils in these spots refuse to give in to wetting, resulting in patches of dead or severely wilted turf.  The water applied wets the turf but does not adequately penetrate the soil surface to reach the root zone.  This is another key – not penetrating leaves (like I said before), but penetrating the soil AND penetrating the soil deep enough to reach the root zone.

In one study of dry spots in turfgrass, it was found that the hydrophobic condition was restricted to the top 1 inch of soil.  The infiltration rate in the dry spots was only 20 percent of that measured in normal areas.  In other analysis, the hydrophobic layer was from 5 to 18 inches thick.  Keep in mind, many different species of turf, crops, shrubs – all kind of plants have varying root zone depths.  Applying wetting agents reduced the severity of the condition, but the most effective solution was to use wetting agents in combination with core aeration.  Also, keeping the soil consistently moist seemed to be the best protection against the increase of dry spots.  Allowing the soil to dry out intensified the predicament.

Many agronomists and other specialists in the management of turfgrass, range land, and forestland have tested the effects of wetting agents on the rate of water infiltration into disturbed and undisturbed soils.  Undisturbed soils are like soils in their natural state, whereas disturbed soils are soils where the soil structure is not in its natural state.  Somebody has messed with it – either through farming, construction, etc.  In general, the results have shown that the extent of improvement in infiltration rate is affected by the type of wetting agent used, its dilution, earlier use of wetting agents on the soil, and the water content of the soil at the time water is applied.  Numerous studies have shown that the permeation rate of a hydrophobic soil, once it has been wetted, remains higher than it was before it was wetted, even if it is allowed to dry out again.

Studies have also been conducted to determine whether wetting agents have any toxic effects on plants.  In tests on barley shoots grown hydroponically (that is, in a nutrient solution rather than in soil), a wetting agent concentration of 300 parts per million (ppm) in the solution caused a reduction of about 70 percent in the dry weight of the shoots.  However, the same concentration in water applied to barley shoots growing in soil or in a sand-peat mixture increased shoot growth only slightly.  When wetting agents are applied to soil, the concentration would have to be much higher than 300 ppm before plant growth would be impaired.

Just like many of the products I have discussed in earlier blog posts, you have to take a hard look at what producers or manufacturers are saying.  Occasionally advertisements for wetting agents and the labels on these products claim or imply that they are universally effective under all soil conditions.  These claims are not always truthful.  Tests in which wetting agents have been applied to normal, “wet-able” soils have failed to substantiate these claims.  Some of these exaggerated claims are that these products will increase water infiltration, plant population, nutrient uptake, and crop yield.  They are effective only on soils that are at least somewhat water repellent.

A number of techniques can be used to determine the extent to which a soil is water repellent.  The most precise methods require laboratory facilities, but several tests can be conducted in the field.  The one real simple and most useful test is simply to place a drop of water on the soil surface and observe how long it takes to penetrate the soil.  On a “wet-able” soil, the water drop will flatten and move into the soil within a few seconds.  On more water-repellent soils, the drop of water will stand more upright and will move more slowly into the soil.

As stated before, water infiltrates more slowly into fine-textured soils than into most coarse-textured soils.  Poor tillage practices can also reduce penetration rates.  Before spending money on a wetting agent, be sure that slow infiltration is being caused by water repellency, not some other factor (Like soil compaction!).  Wetting agents will improve infiltration rates only in soils that have water-repellent properties, regardless of their texture, tilth, and aggregation.

This blog post may be somewhat “high tech”, or, as a minimum, a little odd.  I don’t think it is one of your more common turf topics.  This topic may be out of reach or not feasible for many homeowners.  This topic may be more suited for commercial turf managers, like those who manage athletic fields and golf courses.  But, I think its good to explore these topics for three reasons:  1.  It is good training for a homeowner / turfgrass warrior.  2.  This post may discourage some homeowners / turfgrass warriors from trying something crazy and wasteful with these materials or methods.  3.  And, lastly, I can try to impress you with my extensive knowledge.


In this post I will discuss biostumulants.  What are biostimulants?  They are not fertilizers.  They are NON-NUTRITIONAL growth enhancers.  They are basically plant hormones.  Sometimes these are referred to as PGHs (Plant Growth Hormones).  Hormones (in plants, we often refer to them as phytohormones) are chemical messengers regulating normal plant development as well as responses to the environment.  They stimulate root and shoot growth and increase plant tolerance of certain stresses.  Biostimulants can possibly improve photosynthetic efficiency, increase tolerance of drought, heat, UV light, salinity and even diseases.


There are five groups of plant hormones.  They are:






Adscisic Acid


Each of these hormones has a different influence on plant growth.  Some actually inhibit growth, some enhance growth.  That also depends on what the concentration is of these hormones in the plant.  In many cases, normal levels of hormones enhance growth but higher concentrations, above normal levels, inhibits growth.  So, its fairly safe to say, if you try to make up for a shortage of hormones, like you are trying to offset some environmental or cultural stresses, you may get results.  But, if you use too much, there may be no effect, or, growth may halt.


If my understanding of how biostimulants impact plant physiology is correct, it is probably better to use a biostimulant with more than one (of the 5) hormone and apply it prior to the stress taking place.  And, I mean it needs to be applied 4 to 6 weeks prior to the stress.  Repeat applications may be necessary.  Applications would have to continue throughout the entire stress period.  Most biostimulants are formulated as a liquid.  So, dilution in water and conventional spraying are the application methods.


Now, here’s the rub.  Although much of what I’m saying here has been in my studies and research, I first learned about this from Drs. Xunzhong Zhang and Richard Schmidt.  They are professors of turfgrass ecology at Virginia Polytechnic Institute and State University (Blacksburg, VA; also known as VA Tech).  My certification in Nutrient Management was taught by the faculty at VA Tech. 


I think the jury is still out regarding biostimulants.  Although the VA Tech professors have written about and discussed many of their successes, there really is not enough empirical evidence, in my opinion.  There is lots of “anecdotal” evidence of success out there on blogs and such.  And that anecdotal evidence also includes failures.  The universities and manufacturers will even mention “mixed” results.  I have not heard of or seen consistent results anywhere.  Anyone advertising with boastful claims about biostimulants, well, should be taken with a grain of salt or ignored entirely.  Industry and academics need to do a little more work before I’d stand up and say, “This stuff is awesome!  Go getcha some!”


The good news is that turf managers and university professors all state rather unanimously that biostimulants do not harm turfgrass.  There is no evidence of any harm to any species of turfgrass.  I guess the worst thing that can happen is…..nothing.  Or, as I said, it may inhibit growth.  I guess maybe that’s bad enough.


So, if you are really high speed.  You want to try something out of the ordinary.  You can predict the future with regard to upcoming stresses.  You have a big wallet.  You have the right equipment.  And, you got the time – go for it.  Let me know how it works.


But, remember what I’ve said about some “soil conditioners”, “dethatchers”, “all natural root stimulators”, “soil additives” and all that sort of stuff, usually sold out the back door of a horse drawn wagon by the same guys who sell snake oil.  Be cautious.  I’ve seen jugs of different biostimulants (they say BIOSTIMULANT in big letters on the label) that had no biostimulants inside of it.  I’m not kidding.  They have MAYBE some micro-nutrients….or some other goofy stuff; fermented soybean, cottonseed meal….other minerals, vitamins, and enzymes....dehydrated water….please. 


Reading the label would be another invaluable lesson here.


Listen, I’ve been there.  I’m speaking from experience.  I’m the guy several years back that sprayed ground up fish guts on my lawn.  Yep; I fell for it.  Results?  There were no results.  I’m too embarrassed to tell you how much I paid for that stuff.  My neighbors were not happy with the smell but I did make friends with a lot of neighborhood cats and some other fish eating critters out in the woods.


Biostimulants are “doable”.  They can provide some assistance.  You just gotta be smart about any “program” for your landscape that is not tried and true.  Being a squared away turfgrass warrior means not falling for fads or gimmicks and not blowing your hard earned money on….some….some….snake oil.

Okay, so you are an over achiever.  Obviously you are if you read this blog.  You do everything yourself.  Not only are you a premier Turfgrass Warrior, you are a do-it-yourself mechanic too.  You do a great majority of the work on your automobiles, ATVs, boats and lawn tractors out in your turfgrass.  A nice, thick stand of turfgrass feels good against your back while you are doing preventive maintenance.  And a big part of that preventive maintenance program is draining and filling fluids.  But, this Saturday in particular is not your day.  You’ve managed to spill a petroleum product on your turfgrass.  You kicked over a bucket, dropped a hose or just didn’t place that collection pan in the exact, correct spot.  Now you’ve got some serious problems.


Dr. James B. Beard and Mr. D. Johns, Department of Soil and Crop Sciences at Texas A&M University, have done some fascinating research on the mitigation of spills on turfgrass.  Believe me; information like this is posted in and around all the equipment and maintenance shops at a golf course.  When you have a high number of sophisticated equipment all over a golf course on any given day, this becomes a critical subject and a major training topic.  And, if you are pulling equipment maintenance out on or adjacent to your lawn, you need to probably have this information close by or committed to memory.


A spill of a petroleum product on your turfgrass is going to do something.  Something’s gonna happen and the impact to your lawn will not be favorable.  There will be some sort of impact.  And, there really is no easy way to “remove” a spill from your lawn.  The best you can hope for is to somehow mitigate the impact.  In fact, that’s kind of the goal of the research that those Aggies I mentioned earlier were doing.  Those Aggies developed some ways we can alleviate these stresses, mitigating some of the impacts, and maybe even lessen the “Recovery Time” of the turf.  In many cases, the Aggies were able to cut the recovery time in half.


Let me list the fluids that I’m talking about: Gasoline, Motor Oil, Hydraulic Fluid, Brake Fluid and Grease.  These items can do horrible things to your lawn and your landscape shrubs and trees as well.  Leaf burn in your lawn begins almost immediately when gasoline is spilled on your turf.  Gasoline can completely kill the turf in the area in less than an hour.  Motor oil has a shiny appearance and takes more time than gasoline (maybe up to 48 hours) to do damage.  Hydraulic fluid is more like gasoline but the leaf kill is not as quick as gasoline.  Most hydraulic fluids also have an odor.  Brake fluid has an odor but turns the turf into a grey color then a yellow color but total leaf kill occurred within 24 hours.  Luckily, grease is usually deposited in small spots and can be removed…to some extent.  Grease has real high viscosity.  Grease does not flow (or percolate) as well as the other petroleum products.


The first thing you must do is REACT QUICKLY.  You need to do your activity within the first 20 minutes after the spill.  That’s why in some places you will see materials always standing by for immediate use in case there is a spill.  You need to be able to start working on the spill immediately.  Do not wait for any length of time because the fluid will percolate into the soil and be sucked into the stomates of the plants very quickly.  Both plants and soil are impacted.  All spills, regardless of type, must be dealt with immediately.


Next, the question is:  What material do I need to use?  Again we turn to our Aggie researchers.  They discovered that granular detergent is a good active ingredient to offset the effects of a spill.  It was able to reduce the recovery time from 8 weeks to about 4 weeks.  The turf still got messed up.  But, the turf did not stay messed up for 8 weeks and was able to recover in about 4 weeks.  Turf managers were able to take further action (tilling, seeding, sodding, plugging, etc.) in a much shorter period of time.  The Aggies said that the detergent needed to be thoroughly drenched with water once the detergent was applied.  They also said the recovery was even better if the suds that were created were removed.  They recommended using a vacuum to remove the suds.  In some of my research, I’ve seen authors refer specifically to “dish soap” versus some other types of detergents; like maybe for laundry or vehicles.  Now, detergent will “disperse” the fluid.  It may reduce the severity of the spill but it may also increase the spread of the problem, over a larger area.


Unfortunately, detergent is not that useful against gasoline or grease.  Another “disclaimer” – nothing is really effective on gasoline or grease.  But, detergent is very helpful against motor oil, hydraulic fluid and brake fluid.  Some other materials used on the spills were activated charcoal and calcined clay.  The activated charcoal and calcined clay were not very useful on motor oil and brake fluid spills.  Using activated charcoal and calcined clay on hydraulic fluid is fairly effective, but not as good as detergent.  But, like I said, neither detergent, activated charcoal or calcined clay works well against gasoline or grease.


Well, while I’m on the topic, might as well discuss some other spills on turfgrass.  Perhaps spills which are more likely to happen to a homeowner.


How about a fertilizer spill?  Treating a fertilizer spill would be somewhat the same as treating your lawn if you “over fertilize”.  I advise homeowners all the time when they have burned their lawn with too much fertilizer.  There’s not much you can do; except water and wait.  All fertilizers may burn lawn grasses if improperly applied.  Fertilizers are made up of mineral salts.  Those salts can literally suck the moisture out of the plants and the soil.  If you’ve spilled granular fertilizer on your lawn, see if you can scoop it up, vacuum it up or rake it out as much as you can.  Physically remove as much as you can and/or spread it out as much you can.  Then drench the area.  Soak it the first day.  Then water it every day for a week.  If you’ve spilled (or over applied) a liquid fertilizer, water and wait.  If your spill is with liquid or granules, you may be done for the season.  Live to fight another day.  Remember, like I said above, you’re probably not going to fix it.  You’re trying to mitigate the damage.


How about an herbicide spill?  Or a pesticide spill?  Just like above, if its granular, try to physically scoop up and remove as much of the spill as possible.  If its liquid, watering is good to dilute it.  But, that will also make it spread.  I also spoke about activated charcoal earlier.  Some gardeners say activated charcoal is like using a “de – tox” (detoxification) material for your soil.  It can remove toxins and other bad stuff from the soil.  Using activated charcoal for an herbicide or pesticide spill is a good idea.  Apply it at 5 to 7 pounds per 1,000 square feet.  You need to water that too.  When that operation is complete, you’ll need to scoop up what is left and dispose of it properly. 


Here’s the bottom line:  If you spill something, its gonna hurt your lawn.  Don’t just stand there and scratch your head.  Take immediate action.  Try to be prepared to execute some of these tips.  Doing some of the things I have laid out in this blog post will not make the area look like nothing happened.  Get real.  But, these activities should MINIMIZE the damage to a certain degree AND cut some of the recovery time.  The level of effectiveness of these actions depends on what you spilled, how much you spilled, what species of turfgrass you have, how quickly you take action and how you try to treat the area. 


If there is no chance any of these bad things will ever happen in your lawn, then you didn’t need to read all this.  But, if there is a chance these things could happen, you didn’t waste your time reading this.

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