selecting sand-dominated rootzones for sports … sand-dominated rootzones for sports fields tom...

Selecting Sand-Dominated Rootzones for Sports Fields

Tom Serensits Penn State University

Why Sand ?

Why Sand?

• Many Disadvantages

– Does not much hold water for plant use

– Must water more often

Why Sand?

• Low nutrient retention

(Cation Exchange Capacity) • Must fertilize more often

• Must fight against organic matter accumulation • Must aerify and topdress with sand often

• No soil structure

• Expensive

Why Sand ?

Porosity

Porosity

• Clay – 75% pores, 25% solid

– 65% micropores

– 10% macropores

• Silt – 50% pores, 50% solid

• Sand – 35% pores, 65% solid

– 10% micropores

– 25% macropores

Ideal Soil

Solid Pores

Organic Matter (1-5%)

Why Sand ?

Even after maximum compaction, sand still retains “ideal” pore distribution and therefore continues to drain and retain airspace

Soil Structure

Arrangement of soil particles into groups

Bulk Density

• Under normal conditions, sand has a higher bulk density than clay

• Clay = many pores

• Bulk density affected by compaction

Frequent Question: How many events can a native soil field withstand vs. a sand rootzone?

Answer is 1 game if soil is saturated

And the field is destroyed...

Followed Golf’s Lead

Perched Water Table

Sand – No Structure

Good Balance of Air and Water

Amending a soil

• When amending a high clay soil

– Need a lot of sand (> 60%)

• When amending a high sand soil

– Need only a little clay

Will turf growing on sand wear better than turf growing on soil?

• Components of wear

– Compaction

– Abrasion

– Divoting

Why Sand?

Sand Cap Method

Michigan State Sand Cap Publication

Beaver Stadium

• Built like a road

– 22 inches of compacted silt loam soil over gravel

On-Site Mixing

Need to Use a Quality Sand

Characteristics of a Quality Sand

• Particle Shape

– Angular or Round?

Sand Shape

How important is shape?

Sand Sizes

USGA: 35-55%

USGA: 15-30%

USGA: 15-25% You want a good balance between air-filled and capillary porosity

USGA: min. 6 in/hr

Total Porosity – Sand Effects

• Average sand size increases = T.P. decreases

• Uniformity of sand increases = T.P. increases

• Sand get rounder = T.P. decreases

• **total porosity only tells part of the story

“Holes” in the USGA Specs

Doesn’t regulate too uniform

Calcareous Sands

• Quartz (Silica) sand is best – hard and durable

• Calcareous Sand (calcium carbonates) – Physically breaks down – High pH – High particle density – Calcium Carbonate Equivalent

• < 3% - OK • 3 - 9% - High • > 9% - Problem

– Color?

Sand and Gravel Matching

Gravel Rootzone

Bridging

Permeability

Uniformity


• Bridging: Will sand migrate into gravel?

– Will you need an intermediate layer?

– Largest 15% of rootzone

– Smallest 15% of gravel

• Use wet sand as first layers on top of gravel


• Permeability: Will there be clogging at the interface?

– Smallest 15% of rootzone


D15 (gravel) ≥ 5 x D15 (rootzone)


• Gravel Uniformity: Is the gravel uniform enough?

– Largest 10% of gravel


The Quality Control Program

• Make sure you get what you are paying for

• Work with a soil testing lab experienced with sand-based athletic fields

• Small jobs – the soil test lab may be able to supply the soil specifications

• Large jobs - architect


• Get soil suppliers to submit either blends of individual components

• Lab will test blends to see if they meet spec or will construct blends in lab to determine appropriate ratio

• Once approved by the lab, the soil supplier will be allowed to bid the job


• One of the bidders is awarded the job

• Company makes small batches to be tested. These are called calibration runs

• After the lab has the blenders “dialed in” , a benchmark mix is established


• Confidence intervals are established

• All soil testing up to this point is borne by the soil supplier


• Now begins the quality control phase

• QC tests done every 500 tons mixed at the blending site

– Dig into pile with shovel

– use 4 ft long, 2 inch PVC pipe, cap one end, drive into pile

– Put in bucket and repeat 6 times

– Put on tarp and “quarter” until fill gallon ziplock


• Send someone to check a few piles

• Explain you will be spot checking when the mix arrives as well

• Pay someone to take a small sample of every truck load that arrives. Label it and save it if questions arise later

Components in Rootzone Blends

• Sand

• Organic Matter

• Soil?

Heinz Field

• 85-5-10 Mix

• Percolation rate: 3.5 in/hr

• Aeration porosity: 15%

What does 80-20 mix mean?

• 80% sand, 20% organic matter

• By volume

• 80-20 mix is usually about 0.7% OM by weight

Organic Matter

• Increased moisture retention

• Reduce bulk density

• Buffer capacity

• Increase cation exchange capacity

• Microbial activity

Peat

Reed Sedge Sphagnum

Peat

• Reed Sedge

– North Dakota / Minnesota

– Age: Old

– Stable

– Fine texture

• Sphagnum

– Canada

– Age: Young

– Fibrous

– High OM content

– High water holding

– Lower pH

Organic Matter

• OM should only ever be added at construction

• K. bluegrass deposits 5,000 lbs. of oven dry OM per acre per year

Organic Matter

Topsoil

• “Friend”

• > 3% OM = adequate

• > 4% OM = Good

• > 5% OM = Superior

Sand Rootzone

• “Enemy” (over time)

• > 3% (by wt.) = concerned

• > 4% (by wt.) = may see problems (poor drainage, shallow rooting, divoting)

• > 5% (by wt.) = problems typically evident

Too much organic matter...

Reducing Organic Matter

Dilution

Removal

Cores must be removed

What to look for in a soil test report

• Soil Texture

– % Gravel

– % Sand

– % Silt

– % Clay


• Sieve Analysis

– Breakdown of sand sizes

– Does it meet spec?

– Anything that jumps out?


• Acid Reaction

– Is it calcareous?

• Shape

– Angularity and sphericity

• D15 and D85

– Used for bridging with gravel


• Bulk density

– Indicator of compaction and hardness

– Used to calculate porosities

• Total porosity

– USGA: 35 – 55%


• Air-filled porosity (Macroporosity)

– What % of the pores are airfilled?

– USGA: 15 – 30%

• Capillary porosity (Microporosity)

– What % of the pores are filled with water?

– USGA: 15 – 25%


• Hydraulic conductivity (percolation rate) – USGA: minimum 6 in/hr

• Particle Density

– Density of the solid portion of the soil – Around 2.65 – higher if calcareous, lower if a lot of OM – Needed for porosity calculations

• Organic Matter


• Quality Control Testing

– Particle size analysis with silt and clay combined

– Organic Matter

– Quick turnaround

Other Things to Consider

• What is the soil makeup of the sod?

• Thick cut or thin cut?

• Aerify and topdress with sand similar to rootzone

Reasons for Sand Field Failure

• Pre-installation

– Poor design / sand selection

• Too coarse – will be droughty

• Too fine – slow drainage, compaction

• Wrong particle size distribution


• Pre-installation

– Calcareous sands

– Too much / too little organic matter

– Poor design • Irrigation systems

• Drainage system


• During Installation

– On-site mixing

– No Quality Control testing

– Sod soil with high amounts of fines


• After installation

– Allow buildup of organic matter

• Shallow rooting

• Reduced drainage

• Divoting


• Improper maintenance

– Fertilizer program

– Irrigation scheduling

– Not removing cores

– Not topdressing enough


• Topdressing with the wrong material

• Match topdressing sand with rootzone

– If not, layers can develop (perched water table)

• No fines or gravel


• Loss of turf cover

– No cohesion between particles

– Rely on rhizomes and roots

Plant Growth Regulator Study

Research Trial

• Kentucky bluegrass

• 2 Rootzones – USGA Sand

– Silt loam soil

• Evaluated divot resistance, tiller density, and root mass

Plant Growth Regulator Study

• Plant growth regulator - Reduce vertical shoot growth by altering hormone levels

• Trinexapac-ethyl (TE) - Inhibits gibberellic acid

– Side effects – increased tiller density and rooting

www.turffiles.ncsu.edu

Trinexapac-ethyl Applications

• Rate 0.5 oz/ 1000 ft2

• 28-day intervals

• 2 application regimes

– May – July (3 applications)

– May – Oct (6 applications)

Simulated Football Season

Simulated Football Season

No Wear Medium Wear High Wear

Results

• TE applied from May – July reduced divot size most

– Sand: 10-20% reduction

– Soil: 10% reduction

• TE applied from May – Oct was not better or worse than untreated plots

Results

• Tiller Density

– TE treatments increased tiller density up to 15%

– Root Mass • TE applied from May –

July increased root mass by 10%

Nike Reuse-A-Shoe

Turfgrids (3, 5 g kg-1)

Netlon DuPont Shredded Carpet

Fiber Reinforced Sand Systems

Turfgrids


• Increases surface stability

• Popular on European Soccer fields

• Synthetic fibers sewn into existing turf – Every ¾”

– 7 inches deep


• 22 million fibers

• 25,000 miles of fibers on a single field

• 3% of field

• NFL fields

Fibers

Sewing Needles


• Advantages

– Increase stability

– Less Divoting

– As field get worn, plays better

– Roots intertwine with fibers?

• Disadvantages

– Cannot core aerify

– Cannot re-sod

– Fibers tend to lay over

– Topdressing buries fibers

Final Thoughts

• Sand maintains good air and water balance even under compaction

• Sand-based fields prevent the disaster rain game

• Sand mix must be carefully selected to realize benefits

Final Thoughts

• Maintenance practices must be adjusted and intensified

– Manage organic matter

– More frequent irrigation

– More frequent fertilization

– Topdressing with proper sand

– Maintain turf coverage

– More expensive to build and maintain

Website: http://ssrc.psu.edu “Like” Penn State’s Center for Sports Surface Research @ PSUsportsturf

Penn State’s Center for Sports Surface Research

selecting sand-dominated rootzones for sports … sand-dominated rootzones for sports fields tom...

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