As turf agronomists a common question is “what is the best wetting agent for lawns and turf in Australia?” This blog discusses wetting agents but before we can answer this we need to define what exactly one is.
What are soil-wetting agents?
A soil-wetting agent is “Any compound that causes a liquid to spread more easily across or move into the surface of a solid by reducing the surface tension of the liquid.” Spray adjuvants use this same principle to increase turf chemical contact with for example a leaf but these are not discussed here.
There is a wide range of wetting agents for lawns and sports turf all of which work (to varying degrees) by countering hydrophobic (water-repellant) soils. By doing this they then help to increase uniform water movement through the soil profile, meaning that you use less water to give a more consistent playing surface. Our recent 2022/2023 work into soil wetting agent performance shows how these vary.
Why use wetting agents?
The four reasons for their use are:
1. For localised dry spot treatment;
2. Improve water efficiency;
3. To move water away from the soil surface and
4. As an aid to help chemicals move into the soil.
Managing sand-based soil profiles is difficult in dry, hot conditions, and hydrophobicity results in ‘hot spots’ that dry out faster compared to other turf areas. Soil wetting agents help reduce surface tension and aid uniform water penetration into the soil.
So in answer to the initial question “What is the best wetting agent?”
After years of experience, as sports turf consultants we can say that the Indigo Hydroforce® range is right up there. As well as being excellent soil wetters their low foam formulations mean that there there is less need for an anti-foam type product when mixing. This range also includes HydroForce Rapid, HydroForce Inject for use through injection systems, HydroForce Extend, the dew suppressant, Consume penetrant and Aquimax an innovative water retention agent.
The Hydroforce® range has been researched by some of the world’s most renowned Universities and has been shown to work under all field conditions. They simply are the premium products in Australia.
Results from the use of the Hydroforce range are:
1. A more healthy stress-tolerant turf;
2. Water and chemicals move a lot easier away from the soil surface;
3. Uniform water distribution through the soil and so a deeper root system;
4. Less waste of water as there is less loss to run-off or evaporation;
5. Saves water because there is less loss to run-off or surface evaporation;
Pete Dunn, Course Superintendent at Federal G.C.
‘Mate that HydroForce Ultra is the best product I’ve ever seen by a mile. On the third day at 35°C and we haven’t had to put any hand watering on the greens. We wouldn’t even irrigate if it wasn’t for the surrounds drying out.’…
Dave Ramage the Course Superintendent at Fairbairn GC.
‘Yes, good results so far improved infiltration on some of the heavier soil greens with no water pooling in areas that had before.’…
Do soil wetting agents work?
At Gilba Solutions we are always asking questions. The following is some independent trial work on cool-season bent/Poa annua fairways. These results are also relevant to what is the best wetting agent for lawn areas. Hydroforce® Ultra in a trial vs Dispatch® (Aquatrols) and an untreated control. Throughout the trial Hydroforce® Ultra consistently:
- Improves and maintains turf quality;
- Increases soil volumetric moisture content (VMC %).
Hydroforce® Ultra gives great results on greens.
A US study in 2021 on a mixed Poa/ V8 bentgrass green. Hydroforce® Ultra use at 13L/Ha; Pervade® (Floratine) at 6.4L/Ha. Results show:
- Less localised dry spot compared to the Pervade® treatment or the untreated control;
- Hydroforce® Ultra gives more consistent moisture levels;
- Up to a 30% increase in root mass and
- A dramatic reduction in the need to hand water.
aThe video below shows Hydroforce® Ultra on a golf course fairway in the UK. We’ll let you figure out which half of the fairway was treated with a soil surfactant.
This video is from Ludlow GC in the UK, and demonstrates how water rapidly moves away from the surface after treatment with Hydroforce Ultra. In the UK, Hydroforce Ultra is marketed as Prowet Evolve®.
Research into soil wetting agents
As turf agronomists we like to make sure that any recommendations are supported with good science. The pdf below shows the results of a wetting agent trial we completed in 2019 at Bonnie Donn GC in Sydney, NSW.
2019 Sydney soil wetting agent trial summary
2022/2023 Soil wetting agent trial at Bonnie Doon GC, Sydney.
This is an extension of our 2019 work and is looking at volumetric moisture content, surface hardness using a trufirm and a light box to measure turf health.
Improving turf nematode control.
Treatments were as follows in this nematode control in couch grass study:
- A mixture of the nematicide abamectin and the wetting agent Hydroforce® Ultra;
- Abamectin by itself, and finally
- Hydroforce® Ultra as a stand alone treatment.
- A combination of Hydroforce® Ultra and abamectin provides the best control and
- The stand-alone treatment of Hydroforce® Ultra gives better turf quality than the nematicide by itself.
Hydroforce® Ultra results in more efficient water use and uniform distribution into the soil profile.
Do wetting agents retain water or help it penetrate into the soil profile?
The first wetting agents were used to help water move into the soil profile by reducing surface water repellency and hydrophobicity. Many were excellent at doing this but were also likely to cause turf damage if not watered in immediately.
Over time the chemistry has improved so that now soil wetting agents help water move evenly through the soil profile but also have plant health benefits. That’s a key difference with Hydroforce Ultra.
Not only is it an excellent soil wetting agent but it has many secondary benefits such as improving root volume and turf health.
The soil chemistry of any wetting agent will influence how it performs. For example, in a US study of 15 wetting agents a modified polysiloxane gave the lowest surface tension. This reduces water surface tension to a third of tap water! Examples of this include Consume® and Scrubwet®.
Our current wetting agent trial is now starting to give some pretty interesting results with most products retaining moisture in the soil profile compared to an untreated control.
Does soil wetting agent need watering in?
Soil wetting agents work in the soil, so you need to water them in. The question should be do they need to be watered in immediately? Ideally, they should be watered straight after application. However, our ongoing soil wetting agent trial has shown that if these are applied as per the label they are very unlikely to damage turf. To further increase turf safety certain products are formulated to have an increased level of turf safety. HydroForce Ultra uses an innovative block polymer technology that offers great turf safety. We still recommended irrigating after application to move the product into the root zone but as long as it’s not a hot day it doesn’t have to be straight away.
Are all wetting agents the same?
Due to differences in formulation soil wetting agents differ in their effects on water infiltration, retention, and ability to reduce surface tension. For example, recent wetting agent trials have shown that there a big differences in their ability to retain soil moisture, effects on surface hardness, disease incidence, and turf quality.
How long do soil wetting agents last?
The two main factors influencing this are their chemistry and environmental conditions. Some are marketed as only needing to be applied once-a-season and claim to last up to three months. The issue that we have with this is that you don’t know when they stop working so it can lead to periods when effectively no wetting agent is present. If a soil wetting agent lasts a month and you apply on a regular basis then you avoid these issues developing. Always ask for independent data to support any claims made rather than relying on a glossy brochure.
Why do some soil wetting agents burn grass and cause damage?
Soil-wetting agents break the surface tension of water and help water move through the soil profile. However, their composition differs from most surfactants. Many are based on nonionic surfactants mixed with for example polyoxyethylene esters, or ethoxy sulfates. When you apply these at too high a rate or too high a temperature they can cause membrane permeability problems. This results in the death of roots and leaf tissue.
Some surfactants dissolve cuticle/wax layers on the leaf blades causing discoloration and burning if allowed to stay on the leaf surface too long. Soil wetting agents like Hyroforce Ultra soil wetter contain no harmful chemicals that can cause turf burn. However, as with most things if you apply any chemical when it’s blistering hot and don’t follow the label regarding watering you are asking for trouble.
Can I use washing up liquid as a soil wetting agent?
Of course you can but we don’t recommend it. If you use ordinary washing-up liquid as a soil-wetting agent it will at first give a short-term improvement in water penetration into the soil. However, in the long term, the effects are detrimental to wildlife and the soil itself.
- Many household detergents contain high phosphate levels which can wash into our drains and streams;
- They can be very phytotoxic to plant material;
- Long-term detergent use destroys the soil structure and increases salt levels
All information is provided by Gilba Solutions Pty Ltd. While we endeavour to keep the information up to date and correct, we make no representations or warranties of any kind, express or implied, about the completeness, accuracy, reliability, suitability or availability with respect to the website or the information.
© 2022, Gilba Solutions Pty Ltd, All rights reserved
After Graduating from Newcastle University with an Hons Degree in Soil Science in 1988, Jerry then worked for the Sports Turf Research Institute (STRI) before emigrating to Australia in 1993.
He followed this by gaining a Grad Dip in Business Managment from UTS and has worked in a number of managment roles for companies as diverse as Samsung Australia, Arthur Yates and Paton Fertilizers.
He has always had a strong affinity with the Australian sports turf industry and as a result he established Gilba Solutions in 1993. Jerry has written over 100 articles and two books on a wide range of topics such as Turf Pesticides and Nutrition which have been published in Australia and overseas.