Turf & Rec

Features Agronomy
Know your soil type, water quality and target area before selecting the right surfactant for the job


February 13, 2012
By Mike Jiggens


Topics

Not many years ago, much confusion still existed about surfactants, as
to how they worked, when they worked and if they worked. The air has
cleared considerably since then, but golf course superintendents still
need to know that surfactants are local in nature, meaning there are
several factors which must be taken into account to ensure the right
surfactant is used under the right circumstances.

Bert Brace, vice-president of Aqua-Aid Inc., a manufacturer of surfactant products for the golf market, explained how incidents of localized dry spot on golf courses can benefit from surfactants while speaking at the 23rd annual Professional Turfgrass Seminar in Waterloo, Ont., sponsored by Ontario Seed Company and Nutrite.

He said we all know surfactants work, but, because they are local, the superintendent must take into account the type of soil, water quality, weather conditions and the targeted area—whether it’s a green, tee or fairway.

A surfactant’s label doesn’t take those things into account. Brace said the wrong type of surfactant can be used under the wrong conditions, leading to the superintendent not getting the results he’s after.

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Greens, tees and fairways require different surfactant strategies, he said. The objective with greens is to achieve firm and fast surfaces yet which are hydrated below. A dry surface is wanted for fairways, but also hydrated below.

“We want to go through an irrigation cycle and not worry about wilt and dry spots on fairways.”

Plus growth and hydration below for quick recovery are wanted on tees.

Not every golf course, park or sports field has the same soils. They have different microenvironments and different turf types and different expectations of a surfactant.

Some surfactants help retain water while others help move it. There is a basic molecular difference betwen the two. Because of this, it is important that golf superintendents know precisely what their particular problem is before contacting their sales representative, Brace said. Do they want to move water through the soil profile or do they want to retain water? He said the problem can worsen if the wrong type of agent is selected, and that will lengthen recovery time.

“You need to know if you need to move water, where you need that water location, and the need to hydrate.”
The role of surfactants for wetting agents in turf care is to prevent water repellency, increase water movement and provide hydration.

Penetrating surfactants usually have 15 to 30 days of activity while hydrating surfactants usually range from 30 to 150 days. A product such as OARS (organic acid removal system) from Aqua-Aid is a corrective combination surfactant which acts as a penetrating surfactant yet has a hydrating surfactant with it. It acts like a penetrant and hydrates at the same time.

Clay is difficult to penetrate. If a hydrator is used, it is apt to simply stick on top and soften the top, but not get through. A penetrating surfactant will get through. Penetrating surfactants disperse water uniformly through the soil profile. During their 15 to 30 days of activity, they provide for a drier surface.

If short roots exist and one applies a penetrant, the water can be brought past the roots, resulting in dry spots everywhere the next day. In such a case, a corrective surfactant or hydrator should have been used.

Occasionally following a soil test, it may be discovered that one’s water is too clean. Adding a surfactant is beneficial. If a soil is compacted, and the superintendent isn’t able to aerify, using a surfactant will help with penetration until the chance to aerify is realized.

“And it’s an awesome tool for soil flushing,” Brace said, noting its effectiveness in removing bicarbonates and salts by moving water through the profile.

In general, four to six ounces of a hydrating surfactant will buy about 30 days. Another of Aqua-Aid’s products, PBS150, is a long-term surfactant which will buy 150 days with three applications of four or five ounces, Brace said.

The reason it is so effective, he said, is because it’s a multi-branch surfactant. As one branch is eaten up by a microbe, another one forms, resulting in 30 to 40 per cent more longevity from the chemistry.

A hydrating surfactant will move water both laterally and downward. The more water applied following application of the surfactant, the father down into the profile the surfactant will go.

All surfactants are broken down by microbes, Brace said, adding the fall, winter and spring seasons will see a longer life for a surfactant because microbial activity is less than that experienced in the summer.

A hydrating surfactant can help jump start overseeding when applied afterward. With sand-based root zones and a lot of percolation, retention is sought for shallow-rooted areas. Brace said bunker faces can greatly benefit from a hydrating surfactant when an organic fertilizer is put on them and then sprayed with a hydrating surfactant.

“You’d be amazed how one or two applications of that can buy your bunker faces keeping green and lush throughout the season.”

The question as to why water repellency and localized dry spot develop in the soil and why it is so unique to turfgrass is that, unlike other types of growing media common to agriculture or in greenhouses, turfgrass soil is not turned over.

“In turf, we never turn the soil over. At most, we can do six to eight surface disruptions with aerification. We never get a chance to plow the soil over.”

Without being able to turn over the soil, organic acids build up in the top inch, forming water repellency and localized dry spots.

When temperatures escalate and are aided by humid conditions, that same spot on a green gets larger each successive year. It’s progressive and naturally occurring. When the soil isn’t turned over, the organic acids aren’t given the chance to be mixed into the soil. Brace said that with two applications of six ounces, 27.5 per cent of those organic acids which cause water repellency and localized dry spots can be eliminated.

Because organic acids continually build up on turf, superintendents must continually go after them.

Surfactants are not all the same, Brace said, emphasizing the need to know what is desired from that particular turfgrass surface, whether it’s firm and fast for a putting green, plush for a tee, or the need for good traction on a sports field.

The checklist to consider before selecting a surfactant:
• Soil type (sand, silt, clay, peat)
• Water quality: High salt or high bicarbonates will make the surfactant ineffective.
• Weather patterns: Weather is difficult to predict, but we can predict cycles.
• Root length: For short roots, use a hydrating surfactant. For medium-length roots, use a combination hydrating/penetrating surfactant. For long roots, use a penetrating surfactant.
• Turf variety: All require a different strategy
• Manpower: Is the necessary manpower available to hand water everyday?