Trial Background

As turf agronomists, we like digging into product claims. A case in point is soil-wetting agents. There appears to be a lot of confusion in the marketplace over what grass wetting agents can and can’t do. So in 2022/2023 we carried out some in-depth research into soil-wetting agents. The aim is to see how these products perform against each other. We also looked at how soil wetting agents impact on soil organic matter.

This research isn’t going to make claims about what’s the “best soil wetting agent“. Instead, it’s to see how these perform in the field.

The market for soil-wetting agents for lawns and sports turf is becoming increasingly cluttered. All of these make claims to be the “best” soil wetter and according to some sales reps can do whatever you want them to do!

The trial site was a creeping bentgrass green at Bonnie Doon Golf Club in the Eastern Suburbs of Sydney. This soil wetter trial was a completely randomized block trial comprising 9 treatments with 6 replicates of each. The results are relevant for lawn owners and turf managers.

Soil wetters tested included:

  1. Tricure AD
  2. HydroForce Ultra
  3. A new proprietary formulation containing plant elicitors
  4. Propel
  5. Hydroforce Recovery
  6. Untreated control
  7. HydroForce Ultra at half rates.
  8. H20 Maximizer
  9. HydroLink Rapid

 

Bonnie Doon GC in Sydney trial green
Hydrolink Rapid soil wetting agent
HydroForce Ultra Soil wetting agent
Tricure soil wetting agent
H20 Maximiser

Research into soil wetting agents

We tested these grass wetting agents for:

  1. Surface hardness using a Trufirm metre;
  2. Soil moisture content using a Spectrum TDR350;
  3. Turf Quality. For this trial we use a light box with a digital camera to take images under constant light conditions. The images are then run through proprietary software to determine their quality ranking.
  4. Dollar spot. After 106 days this made an appearance. After this counts were made every time readings were taken.

 

The Trufirm surface hardness tester has bluetooth capability
The Trufirm has an impact hammer that mimics the shape of a golf ball.
Light box with digital camera for turf quality assessments
TDR 350 portable soil moisture sensor
Muffle furnace for loss on ignition

Soil wetting agent effect on turf quality

Throughout the trial, only the Hydroforce Recovery treatment (Treatment 5) has significantly lower turf quality than the control (Treatment 6). There is no significant difference between the turf quality of any of the other treatments and the control.

The Propel treatment has a significantly higher turf quality than the Hydroforce Recovery treatment. This is a result of it containing humic acid.

Over the 200-day trial period, there are only three occasions where there are significant differences in turf quality.

 

 

 

Variations in Turf Quality over time as a result of treatment
Effect of wetting agent treatment on turf quality
Soil moisture variations vs wetting agent treatment over time

Soil wetting agent effect on soil moisture content

Only the Hydrolink Rapid grass wetting agent and Gilba Solutions proprietary formulation have significantly higher moisture contents than the control. Hydrolink Rapid also has significantly high moisture content than Hydroforce Recovery and the half rates of HydoForce Ultra.

Significant differences in moisture content are seen on 3, 22, 95, 105, 159, 173, 187, and 200 days post first Treatment. In total 23% of the time, significant differences are seen between the treatments in relation to soil moisture content.

Variations in Soil moisture over time
Soil moisture content difference by treatment vs control
Soil moisture variation vs wetting agent treatment over time

Surface hardness

The Propel, H20 Maximiser and Hydrolink Rapid treatments are the only ones with no significant difference in surface hardness in comparison to the control.

Significant differences in Trufirm Readings are only apparent 29 days post first treatment.

Trufirm variations over time by treatment
The effect of soil wetting agents on surface hardness measured using a Trufirm
Trufirm readings over time vs Treatment over time

Dollar spot incidence

The results of the number of infection centres are split between treatments that give lower numbers than the control and those that show no difference from the control. Although dollar spot is not a common disease for Australian lawn owners the use of wetting agents for lawn disease control is a novel approach we think has considerable merit.

The soil wetting agents showing fewer infection centres are Tricure, Hydroforce Ultra, Gilba Proprietary, Propel, and Hydroforce Recovery.

Those showing no difference from the untreated control are half rates of Hydroforce Ultra, H20 Maximiser, and Hydrolink Rapid.

Gilba Proprietary, Propel, and Hydroforce Recovery all have significantly fewer dollar spot infection centres than the untreated control.

Using soil wetting agents to counter dollar spot
Soil wetting agent treatment impact on dollar spot infection centres
Soil wetting impact on turfgrass disease and dollar spot incidence

Future research into soil-wetting agents

As a result of this trial, we are extending it into 2023-2024. However, there are going to be four major modifications to the protocol. We believe that this work will be of practical use on soil wetting agents for turf managers and for wetting agents for lawn owners.

  • Firstly, we will take moisture readings at both 37mm and 75mm depth. This allows us to get an idea of what is happening in the upper thatch layer,  and takes into account the findings of Leinauer et al (2007)1Leinauer, B., Karcher, D., Barrick, T., Ikemura, Y., Hubble, H., and Makk, J. 2007. Water repellency varies with depth and season in sandy rootzones treated with ten wetting agents. Online. Applied Turfgrass Science doi:10.1094/ATS-2007-0221-01-RS. that the efficacy of wetting agents is greatest at depths of 2.5 cm or less.
  • Secondly, we will subject the turf to moisture stress. In the marketing literature, Treatments 1 and 2 both claim to maintain, if not improve turf quality after multiple applications under stress conditions.
  • Thirdly, we will carry out the water drop penetration time (WDPT) test. This will allow us to measure the actual water repellency of the field-moist samples at depths of 0-2, 2-4, and 4-6cm and get an idea of wetting agent longevity.
  • Lastly, we are going to drop some of these soil surfactants and look at some alternatives. Those to go are HydroForce Recovery, the half rates of HydroForce Ultra, the Maximiser H20, and Hydrolink Rapid.
Poster for soil wetting agent trial Year 1 2022/2023
Full 2022 Performance of several soil wetting agent report

References

  • 1
    Leinauer, B., Karcher, D., Barrick, T., Ikemura, Y., Hubble, H., and Makk, J. 2007. Water repellency varies with depth and season in sandy rootzones treated with ten wetting agents. Online. Applied Turfgrass Science doi:10.1094/ATS-2007-0221-01-RS.
jerry spencer senior turf agronomist
Senior Turf Agronomist at Gilba Solutions Pty Ltd | 0499975819 | Website

Graduated from Newcastle University with an Hons Degree in Soil Science in 1988, Jerry then worked for the Sports Turf Research Institute (STRI) as a turf agronomist before emigrating to Australia in 1993.

He followed this by gaining a Grad Dip in Business Management from UTS. He has worked in a number of management 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 as an independent sports turf consultancy 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.