Page 19 - GreenMaster Winter 2025

The Wetting Agent Paradox:
When a Solution Becomes a Problem
Figure 1. Hydrophobicity, determined by molarity of ethanol droplet (MED) test, of hydrophobic or fresh sand columns receiving three sequen-
tial treatment applications and following washes. Treatments included an alkyl block polymer (ABP), a polyoxyalkylene polymer (PoAP), and
water, in addition to an untreated control (untreated sand). Bars labeled with the same letter for each sand were not significantly different
based on Fisher’s Protected LSD at P < 0.05.
between surface tension and
hydraulic conductivity (Song et al.,
2014). Collectively these results
suggested that a wetting agent
product that creates a lower surface
tension would result in a faster water
infiltration into water-repellent soil.
As a soil surfactant, wetting
agents are often made from
petrochemicals or plant-based
compounds (Nikolova and Gutierrez,
2021). These compounds are, by
nature, organic compounds, which
could theoretically coat the soil
particle surfaces and become the
source of soil water repellency. This
is especially true for some compounds
that exhibit a strong sorption to the
hydrophobic soil surface. Recent
research conducted at the UofM has
confirmed that some wetting agent
chemistry might contribute to the
problem of soil hydrophobicity under
certain conditions (Song et al., 2021).
MATERIALS & METHODS
The UofM laboratory research
compared two types of wetting
agents beside distilled water-only
treatment as a control. One wetting
agent used was in the chemical group
of polyoxyalkylene polymer (PoAP),
such OARS (80% polyoxyalkylene
polymers and 10% potassium salt of
alkyl substituted maleic acid; AQUA-
AID Inc., Rocky Mount, NC, USA), and
another belonged to the chemical
group of alkyl block polymer (ABP),
such as Matador (100% alkyl block
polymer; EnP Investments LLC.,
Mendota, IL, USA).
In the laboratory, two types of
silicon sands: one sample collected
from a putting green with documented
soil hydrophobicity and the other
sample of fresh, unused, wettable
sand, were packed separately in PVC
columns and were subjected to
simulated treatment applications and
the subsequent irrigation events.
After each treatment cycle, which
consisted of one wetting agent
application and three sequential
washes, the entire sand column was
oven-dried at 50°C to simulate drying
events common during summer
months. The entire experiment
involved three treatment cycles,
simulating repeated season-long
wetting agent application, irrigation
events and periodical droughts.
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