docSelecting Sand-Dominated Rootzones for Sports Fields
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Selecting Sand-Dominated Rootzones for Sports Fields
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 Pores Solid 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% You want a good balance between air-filled and capillary porosity USGA: 15-25% 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 Sand and Gravel Matching • 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 Sand and Gravel Matching • Permeability: Will there be clogging at the interface? – Smallest 15% of rootzone – Smallest 15% of gravel D15 (gravel) ≥ 5 x D15 (rootzone) Sand and Gravel Matching • Gravel Uniformity: Is the gravel uniform enough? – Largest 10% of gravel – Smallest 15% 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 The Quality Control Program • 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 The Quality Control Program • 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 The Quality Control Program • Confidence intervals are established • All soil testing up to this point is borne by the soil supplier The Quality Control Program • 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 The Quality Control Program • 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” Sand Rootzone • “Enemy” (over time) • > 3% OM = adequate • > 3% (by wt.) = concerned • > 4% OM = Good • > 4% (by wt.) = may see problems (poor drainage, shallow rooting, divoting) • > 5% OM = Superior • > 5% (by wt.) = problems typically evident Too much organic matter... 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 What to look for in a soil test report • Sieve Analysis – Breakdown of sand sizes – Does it meet spec? – Anything that jumps out? What to look for in a soil test report • Acid Reaction – Is it calcareous? • Shape – Angularity and sphericity • D15 and D85 – Used for bridging with gravel What to look for in a soil test report • Bulk density – Indicator of compaction and hardness – Used to calculate porosities • Total porosity – USGA: 35 – 55% What to look for in a soil test report • 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% What to look for in a soil test report • 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 What to look for in a soil test report • 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 Reasons for Sand Field Failure • Pre-installation – Calcareous sands – Too much / too little organic matter – Poor design • Irrigation systems • Drainage system Reasons for Sand Field Failure • During Installation – On-site mixing – No Quality Control testing – Sod soil with high amounts of fines Reasons for Sand Field Failure • After installation – Allow buildup of organic matter • Shallow rooting • Reduced drainage • Divoting Reasons for Sand Field Failure • Improper maintenance – Fertilizer program – Irrigation scheduling – Not removing cores – Not topdressing enough Reasons for Sand Field Failure • Topdressing with the wrong material • Match topdressing sand with rootzone – If not, layers can develop (perched water table) • No fines or gravel Reasons for Sand Field Failure • 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% Turfgrids (3, 5 g kg-1) Fiber Reinforced Sand Systems Nike Reuse-A-Shoe Netlon Turfgrids DuPont Shredded Carpet Fiber Reinforced Sand Systems • Increases surface stability • Popular on European Soccer fields • Synthetic fibers sewn into existing turf – Every ¾” – 7 inches deep Fiber Reinforced Sand Systems • 22 million fibers • 25,000 miles of fibers on a single field • 3% of field • NFL fields Sewing Needles Fibers Fiber Reinforced Sand Systems • Advantages • Disadvantages – Increase stability – Cannot core aerify – Less Divoting – Cannot re-sod – As field get worn, plays better – Fibers tend to lay over – Roots intertwine with fibers? – 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 Penn State’s Center for Sports Surface Research Website: http://ssrc.psu.edu “Like” Penn State’s Center for Sports Surface Research @ PSUsportsturf
