AGCSA

Volume 2.5 - The Effects of Soil Inclusions on Soil Physical Properties and Athletic Field Playing Surface Quality

The Effects of Soil Inclusions on Soil Physical Properties and Athletic Field Playing Surface Quality
Andrew S. McNitt and Peter J. Landschoot, Turfgrass Science team, Department of Agronomy, Pennsylvania State University

Australian Turfgrass Management Volume 2.5 (October - November 2000)

 

In this study we wanted to determine if the addition of various soil inclusions alters turfgrass wear resistance, soil physical properties, and/or playing surface quality (hardness and traction).

PROCEDURE

Field plots were established at the Joseph Valentine Turfgrass Research Center in September of 1995. The plot area consisted of a gravel drainage layer overlaid by a 62.5mm intermediate layer of fine gravel and course sand. Over this was a 100mm layer of a 90% sand, 10% sphagnum peat (v/v) rootzone mix.

The experimental design was a split plot (plots split by wear) with three replications. A grid of 10ft x 10ft treatment plots was laid out over the 100mm of rootzone mix and frames 150mm high were installed. The frames were filled with the mixed soil inclusion/root-zone treatments and levelled the surface by raking and hand tamping.

The Netlon treatments were filled to within 15mm of the surface and then top dressed with unamended rootzone mix. With the Sportsgrass treatment, rootzone mix was filled to within 25mm of the top and the Sportgrass was cut to size and laid. Rootzone mix was then broomed into the surface so only 3.5mm of fibre was protruding from the surface.

The frames were then removed and the plots were seeded with SR 4200 perennial ryegrass. Nutrients and water were applied as needed and the turf was mown twice per week with a reel mower at a height of 35mm.

Treatment plots were split with three levels of wear. These were; no wear, medium wear (approximating 3 NFL games/week), and high wear (approximating 7 NFL games/week). Wear was applied with a Brinkman Wear Machine.

Soil physical properties included soil bulk density, soil water content and water infiltration rate. Surface hardness was measured using a Clegg impact soil tester (2.25kg), linear traction measurements were taken using PENNFOOT, configured with a weight of 268lb and a studded NFL boot. Turfgrass density was rated visually and recorded on a scale of 0 to 5. At the end of the study divots were created using a pitching wedge head attached to a weighted pendulum mounted on a three-point hitch. The maximum width, length and depth was measured.

Turfgrass density, soil bulk density, soil water and hardness was collected on six occasions. Water infiltration rate was measured twice and divot measurements were made at the conclusion of the experiment.

This table lists the individual treatments and the rate of soil inclusions on a percent by oven dry weight of the sand root-zone.

TREATMENT

Rate of Soil Inclusion (%dry wt)

Control
DuPont Shredded Carpet
Netlon
Nike Light
Nike Heavies
Sportgrass
Turfgrids

0.0%
0.5, 1.0, 2.0, 3.0%
0.3%, 0.5%
3.0%
3.0%
NA
0.3%, 0.5%

 

RESULTS

Summary Table. Number of rating dates (max 6) that a treatment main effect mean is significantly different (higher or lower) than the control. Divot
length was measured only once. The mean divot length is listed in the table. # = number rating dates

Turfgrass Density
(wear resistance)

Soil Bulk Density
(compaction resistance)

Soil Water Content Surface Hardness Traction

Divoting
(length)

Treatment

Treatment

Treatment

Treatment

Treatment

Treatment

cm

Nike Lights
Nike Heavies


DuPont S.C. 2%
DuPont S.C. 3%
Turfgrids 0.3%
Higher
CONTROL
Lower
Sportgrass

5
4


2
1
1



3

DuPont S.C. 3%
DuPont S.C. 1%


DuPont S.C. 2%
Nike Heavies
Nike Lights
DuPont S.C. 0.5%


Turfgrids 0.3%
Turfgrids 0.5%
Lower
CONTROL
Higher
DuPont S.C. 0.5%
Turfgrids 0.5%
Netlon 0.5%

6
5


5
5
5
3


1
1



1
1
5

Turfgrids 0.5%
Turfgrids 0.3%


DuPont S.C. 1%
DuPont S.C. 0.5%
DuPont S.C. 2%
Higher
CONTROL
Lower
DuPont S.C. 0.5%
Nike Heavies
DuPont S.C. 3%


Netlon 0.5%
Turfgrids 0.5%
Nike Lights
Sportgrass

4
3


2
1
1



1
1
2


2
2
5
5

DuPont S.C. 3%
Nike Lights


DuPont S.C. 2%
DuPont S.C. 1%
Nike Heavies
Softer
CONTROL
Harder
DuPont S.C. 0.5%
Netlon 0.3%
Netlon 0.5%


Sportgrass
Turfgrids 0.3%
Turfgrids 0.5%

6
6


4
1
1



1
6
6


6
6
6

Sportgrass
Higher
CONTROL
Lower
DuPont S.C. 2%
Nike Heavies
Nike Lights
Turfgrids 0.5%


Turfgrids 0.3%

1



1
1
1
1


2

Sportgrass
Turfgrids 0.5%


DuPont S.C. 3%
Turfgrids 0.3%
DuPont S.C. 2%
Netlon 0.5%


DuPont S.C. 1%
Netlon 0.3%
Nike Light


DuPont S.C. 0.5%
Nike Heavies
CONTROL

LSD

15.2
16.6


18.2
18.6
20.0
20.8


22.5
23.3
23.4


24.4
24.5
29.4

3.0

Soil Physical Properties and Playing Surface Quality

In the summary table we attempted to summarise how the treatment main effects differed from the control on the six rating dates of this study. This summary table may give an incomplete picture of the dynamic nature of the property being measured as different levels of wear are imposed over time.

Soil Bulk Density

In this experiment the recycled products (Nike and DuPont),tended to reduce soil bulk density. A lower soil bulk density means lower soil compaction. Soils lower in bulk density typically exhibit lower resistance to root penetration.

The lower soil bulk densities are most evident for the recycled products that are added to the sand at the rate of 3% by weight. We could expect that adding 3% of a soil inclusion, lighter than soil, to a sand root-zone would decrease bulk density. While the high rates of the recycled products show the most dramatic differences, these results are not simply rate dependent.

The Netlon 0.5% treatment was the only inclusion to consistently produce a bulk density higher than the control; however, Turfgrids and Netlon typically had bulk densities higher than the recycled products with the exception of the DuPont Shredded Carpet 0.5% treatment. Obviously, the rate of DuPont Shredded Carpet affects bulk density. It should be noted, that it would be impractical to add 3% by weight of Netlon or Turfgrids to a root-zone.

Surface Hardness

Surface hardness has been defined as the ability of a surface to absorb impact energy. High surface hardness could result in greater injury to players during impact situations, whereas lower surface hardness values may create early fatigue in players leg muscles.

The manufactured products (Netlon, Sportgrass, and Turfgrids) produced higher Gmax (surface hardness) values than either the control or the recycled product treatments on each rating date over both years of the test. The DuPont Shredded Carpet 3% and Nike Light 3% had lower Gmax values than the control on every rating date over both years of the test, with differences becoming more pronounced after wear was applied.

Soil Water Contents

Soil water content is a measure of the total amount of water held in a soil and does not indicate the amount of plant-available water. Soil water contents varied with the Turfgrids 0.5% treatment having higher soil water content that the control on four out of the six rating dates and Turfgrids 0.3% having higher soil water content on three dates. Both Sportgrass and Nike Light were lower in soil water content than the control on five of the six rating dates.

Turfgrass Density

Both Nike products provided greater turfgrass wear resistance, as reflected in turf density ratings, than the control on over half of the rating dates. Sportgrass exhibited lower density than the control on three of the six ratings dates and only after wear was applied.

Water Infiltration

Water infiltration is a measure of the rate at which water moves into a soil. Low infiltration rates and poor surface drainage can result in puddling and wet playing conditions. Sportgrass had a higher water infiltration rate than all other treatments in 1996. DuPont Shredded Carpet 2% and Turfgrids 0.5% had infiltration rates higher than the control in 1996. At the end of this study all treatments had infiltration rates greater than 500mm per hour. This is considered adequate or high for most athletic field root-zones.

Traction

Traction of a playing surface can be defined as the horizontal resistance a surface provides to an athlete while wearing cleated or studded footwear.

Few traction differences were found in either 1996 or 1997. At various times throughout the study a treatment may have exhibited traction values lower than the control, but no trend is evident.

Divoting

Divoting is the complete shearing and removal of portions of the turfgrass. In American football this type of wear can account for significant turf loss.

All of the treatments in this study produced shorter divots than the control, with Sportgrass producing shorter divots than all other treatments when averaged over the three wear levels. The presence of the inclusions added some shear strength to the turf surface thus reducing divot length. This was most evident after wear was applied and thus turf footing decreased. When there was no wear and 100% turf cover only Turfgrids 0.5% provided significantly shorter divots.

PRODUCTS

This section examines each of the inclusions individually.

DuPont Shredded Carpet

The addition of DuPont Shredded Carpet to the sand root-zone in this study significantly reduced soil bulk density. Although this trend was evident when no wear was applied it became greater as the wear level increased. This indicates that the material lowers bulk density as well as resists compaction as wear increases. The greater the rate of DuPont Shredded Carpet added, the lower the bulk density.

Along with the lower bulk density we also noted a decrease in surface hardness. The more DuPont Shredded Carpet at the 3% rate always provided lower surface hardness values than the control over both years.

In addition to lower bulk density and surface hardness, DuPont Shredded Carpet reduced the length of divots. All rates of DuPont Shredded Carpet reduced the length of divots when compared to the control.

DuPont Shredded Carpet produced no consistent decrease or increase in traction or soil water content over the control. There was a slight increase in turfgrass density when compared to the control, especially in the high wear plots.

Netlon

The addition of Netlon to the sand root-zone significantly reduced divot length when compared to the control.

The addition of Netlon significantly increased surface hardness on all rating dates over the two year study. The 0.5% rate produced a bulk density that measured significantly higher than the control on five of the six rating dates.

Overall, Netlon had no consistent effect on traction, infiltration, turfgrass density, or soil water content under the conditions of this study.

Nike Light and Heavies

These two products produced similar results for some of the properties measured and different results for others. They both reduced soil bulk density on five out of the six rating dates and both showed greater wear resistance than the control on over half of the rating dates.

Sportgrass

On average, Sportgrass reduced divot size more than any other treatment.

Sportgrass was the only treatment to measure higher in traction than the control. On the Oct. 18, 1996 rating date, Sportgrass measured higher in traction than all other treatments on the high wear plot.

Sportgrass was significantly higher in surface hardness than the control on all six rating dates and had a lower soil water content than the control on five rating dates. It also had a lower turfgrass density than the control on three rating dates.

Turfgrids

Turfgrids 0.3% and 0.5% both reduced divot length after wear was applied. Turfgrids 0.5% was the only treatment to reduce divot length, compared to the control, when no wear was applied. Both Turfgrids treatments measured higher in soil water content on over half the rating dates. In 1996, Turfgrids 0.5% had an infiltration rate higher than the control.

Both of the Turfgrids treatments tested higher in surface hardness than the control on all rating dates. The Turfgrids 0.3% had lower traction values than the control on two out of the six rating dates.

Turfgrids had no consistent effect on soil bulk density or turfgrass density.

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