Features Agronomy
Two-year sports field study generates benchmarking, permitting data

A project to verify information found in the book Athletic Field Construction Manual has produced valuable information pertaining to benchmarking and permitting of municipal sports fields.

Speaking in September at Sports Turf Canada’s 27th annual fall field day at Guelph’s Cutten Fields, Ontario Ministry of Agriculture, Food and Rural Affairs turfgrass extension specialist Pam Charbonneau said the purpose of the two-year study was to compare data from real world field usage on specific field types with information contained in the manual.

“We wanted to measure and document field performance and compare that to usage and maintenance input,” she said.

During the summers of 2013 and 2014, sports fields from three different undisclosed municipalities were examined for the study. The manual recognizes five different categories of sports fields, from Category 1 fields (the highest of quality) to Category 5 (the lowest of quality). The primary criteria for determining category type is soil texture.

“If you have a really high sand content soil and low per cent silt and clay, you have a Category 1.”

There were, however, no Category 1 fields found in any of the municipalities which could be studied for the project. Nor were there any fields among the trio of municipalities which fell into the Category 2 classification, designated by the manual as that having less than 25 per cent silt and clay.

Charbonneau and summer student Emily Hartwig instead conducted the project by studying Category 3, 4 and 5 fields. Respectively, their silt and clay percentages, according to the manual, were to be between 25 and 35, between 36 and 45, and more than 45.

Aside from their silt and clay content, the fields were assessed according to such other criteria as sub-surface drainage.
Charbonneau said a field might have only about 8 per cent silt and clay, which would ordinarily classify it as a Category 1 field, but if it was void of sub-surface drainage, it was automatically downgraded to a Category 5 field.

Irrigation is required for Category 1 and 2 fields, but is optional for those in Categories 3 and 4 and not required at all for Category 5 fields. The same guidelines apply for lighting.

According to the manual, the number of permitted usage hours per season for a Category 1 field is 450. Toronto’s BMO Field is an example of a Category 1 field which matches the criteria set out in the manual.

A Category 2 field would see up to 550 hours while Category 3 through 5 fields would see, respectively, 700, 450 and 450.
“What we wanted to do with this project was to see if those numbers were accurate,” Charbonneau said.

One of the questions for which an answer was sought was: how many hours of play is too much or the right amount?

The study also sought to determine the percentage of cover for each field, including turfgrass species, weeds which were present, and the numbers and sizes of bare spots. Surface hardness was tested using a Clegg hammer, and visits to each of the fields under study at different points during the summer provided information as to their performance throughout the season.

Because of their inability to find any Category 1 or 2 fields in either of the three volunteer municipalities, Charbonnea and Hartwig settled on Category 3, 4 and 5 fields, finding four fields in each municipalities which met those categories.

“We tried to pick mostly soccer fields so that we could compare apples to apples,” Charbonneau said.

A visual visit of each field was made at the outset of the study, and then the researchers returned on three other occasions throughout the season. In the first year of the study, visits were made in June, July and August.

Surface hardness was tested each time along with a note of the percentage of cover on each playing surface. At the end of the season, permitted usage data was obtained from each participating municipality and a summary was made of each field’s maintenance practices.

Charbonneau summoned a team of authorities to visit the fields and rate them based on the data obtained. Providing their input at the end of the first year of the study were Ken Pavely of Lawn Life, former City of St. Catharines parks manager and current Niagara College instructor Bob Kennedy, Paul Turner of G.C. Duke Equipment and Ben Tymchyshyn of MMM Group. Offering their assessment for this season’s second year of the study were Pavely, Gord Dol of Dol Turf Restoration and David Smith of DCS Agronomics.

“They had a lot to say,” Charbonneau said. “I couldn’t have done this project without them. I needed an independent third party group to look at these fields and rate them.”

For the soil texture analysis aspect of the study, soil samples were taken from each of the fields yet from areas that likely would not have been modified. Such areas didn’t include the goal mouths, which might have been topdressed several times over the years, nor the centre circles. Instead, sampling was done along the sidelines.

“Hopefuly that was reflective of what was there at the beginning.”

It was the suggestion of Dr. Robert Sheard, author of the Athletic Field Construction Manual, that sampling be done in those areas which might never have been modified.

Charbonneau said both she and Hartwig had a difficult time getting their soil probe more than a couple of inches into the soil on most of the fields, suggesting it was likely a reflection on the amount of compaction they have undergone over the years.

“What we ended up finding was that these fields were either 25 to 35 per cent silt and clay, 36 to 45, or greater than 45.”

During each of the three yearly visits, the fields were tested for surface hardness and an analysis of percentage cover was made. Goal mouth areas reflected the greatest amount of wear, the centre circles were subjected to intermediate wear, and the sideline areas showed little wear.

Additional notes were taken for fields with sub-surface drainage, irrigation and lighting.

Most municipalities don’t classify their fields according to the classifications denoted in the manual, choosing instead to rate them as A, B or C fields. The inconsistency is that fields which have lights, irrigation and washroom facilities tend to be rated as class A fields with no regard to their soil type.

Goal mouth data presented a fairly accurate idea of what was happening with the rest of the field, Charbonneau said.

At a Category 3 field in one of the municipalities, the goal mouth area at the beginning of the study presented a fair amount of Kentucky bluegrass, a little perennial ryegrass, a fair amount of annual bluegrass and considerable bare area. As the season progressed, the same goal mouth became increasingly more bare while the percentage of desirable turfgrass species declined. By season’s end, the goal mouth was almost completely bare.

Annual bluegrass, Charbonneau said, tends to present itself under situations of low fertility, compaction, short mowing heights and excessive moisture.

“If you are seeing annual bluegrass in your fields, those are some of the conditions that contribute to it.”

Clegg hammer testing on the goal mouth indicated surface hardness wasn’t too excessive at the outset of the season but got increasingly harder by mid-season. By the end of the season, it was less hard which Charbonneau presumed was due to aeration having been done.

The goal mouth of a Category 5 field had been sodded before the start of the season, but was already a bit worn at the season’s beginning. By the end of the season, it had lost almost all of its Kentucky bluegrass cover, had a little of perennial ryegrass remaining, but was mostly bare. The field had been allotted almost three times the permitted hours the manual prescribes for its category.

The team of experts which rated the fields adopted a similar rating system to that used in the National Turfgrass Evaluation Program (NTEP), employing a 1-9 scale in which 6 was deemed acceptable while anything less was regarded as a failure.
The fields were also rated for their density and uniformity. Charbonneau noted a weekend-long tournament had been played on all studied fields within one of the participating municipalities just prior to their assessment, and that it wasn’t really a fair representation of them.

Two fields from one of the municipalities earned a passing grade and happened to be those with the fewest permitted hours.
In general, the percentage of weed cover was low on the fields studied. Prostrate knotweed was the most prevalent and some clover was found in non-compacted areas of the sidelines. Some fields had standing water.

Charbonneau said it is important for sports field managers to know what is happening under their turf. She added resodding goal mouths with Kentucky bluegrass in the fall “is really just a band-aid solution,” noting it doesn’t last throughout the season.

Many of the fields under study had drainage issues, and those which were irrigated had high populations of annual bluegrass.
“I think it’s easy when you’ve got irrigation to put it on a little too often. When you do that, you get a lot of annual bluegrass because there’s too much water and too much compaction because you have too many permitted hours and sometimes not enough nitrogen.”

She said she suspects the number of recommended permitted hours will have to be lowered for the manual, and hopes once all data is obtained from the 2014 year of the study that some good numbers will be recommended.

“Frequent overseeding is really important, especially if you start with a sodded goal mouth. It’s important to keep going in there and adding other species besides perennial rye that are a little bit more tolerant to wear.”

Charbonneau suggested to her audience of sports turf managers to implement such cultural practices as deep tine aeration, verticutting and drill and fill to alleviate compaction.

“I think a lot of these fields can really benefit from that type of cultural practice.”

She hinted poa suppina is a potential solution for goal mouths and other areas of heavy wear.