Routine care

Field assessment

Begin with field assessment

Field assessment involves analyzing the condition of the field as well as conducting a thorough review of all current management practices that influence field condition and performance.

Managers should walk their fields regularly with coaches and administrators to identify those fields that need immediate attention for safety reasons and playability.  Field assessments should be conducted before and after spring sports, before and after summer sports camps, before the fall football season and at the end of the season. 

Areas that require immediate attention can be identified by crew members once they are trained on what to look for.  The more information you have on hand, the better you can tailor your field management practices to keep the field functional and safe.  Crews can assist managers by communicating their observations.

Writing detailed observations, keeping maintenance records, documenting use and taking photos can help you assess how play impacts the turf density and playability of each of your fields.  This data will help you prioritize which fields need immediate attention. Keep in mind that written documentation can be very useful when requesting additional resources to make field improvements.

field assessment resources

The Cornell Sports Turf Field Assessment Sheet lists a number of factors that must be observed and rated when evaluating field conditions. The results will help you decide if you should continue your current management program, reassess your program or decide if renovation is needed. An example of a completed Field Assessment sheet.

Site assessment tools include:

 

  • Knife
  • Soil probe
  • pH kit
  • Grass and pest identification books
  • Camera.

However, your eyes may be the best tools of all.  Address the following questions as you walk your fields:         

  • Does the turf look green and healthy?
  • Are good healthy roots present?
  • What is the degree of bare and worn areas?
  • What is the condition of the playing surface? 
  • What about the degree of compaction?
  • Is standing water present?
  • Are there any clues about field drainage?
  • How much pest pressure, percent weed, insect and disease pressure, is present?

Ohio State University had developed the Report Card for Rating Athletic Fields which is another valuable management tool to use when assessing fields, determining management strategies and tracking progress towards achieving field improvement goals. Directons for using the OSU report card.

 

Mowing

Mowing involves the periodic removal of turfgrass leaves and is the most basic and time intensive of all the routine turfgrass management practices. Mowing increases shoot density by increasing tillering (stems that develop from the crown of the parent plant) and ultimately improves site functionality.

Effective mowing height is determined by: grass species and variety, site use, level of management, desired field conditions, traffic level and other management practices. Turf mowed below or above the recommended cutting height for an extended period of time may not be able to perform as expected or desired.

Turf mowed too low and scalped routinely will have a reduced root system, shallow roots and lower stored food reserves resulting in a weakened turf which is more susceptible to pest pressure and requiring more frequent irrigation and fertilization. You can also expect the encroachment of aggressive weeds with lower turf density. 

Keys to proper mowing

Mowing height

Mowing at 3” or higher does not increase traffic tolerance. However, the turf will have a deeper root system and greater access to water and nutrients and will help reduce weed pressure.  The lower shoot density of higher cut turf can give a more open and shaggy appearance. During times when the fields are not in demand mow higher.

For increased density pick a mowing height and stick to it throughout the growing season. If you want to change the mowing height, reduce it gradually (in ¼" – ½" increments per week or mowings) to avoid removing excessive leaf area, scalping or weakening the turf.

There is no need to raise the cutting height in the summer on non-irrigated droughty sites. At this time almost all the root growth of cool season grasses is over until the fall so raising the cutting height won’t encourage deep root growth. However, more leaf area means more carbohydrates , the food source for plant growth.

If you get behind on the mowing and the turf grows much higher than desired gradually lower the height of cut over a couple of mowings. Think of returning clippings as providing free food, supplying nitrogen, phosphorus and some potassium. 

However, leaving excessive clippings on the field (besides looking unattractive) can smother grass, cause heat stress and keep the area beneath the clippings moist, providing an ideal environment for disease organisms to flourish.  The particular sport will ultimately determine mowing height. Based on grass species, the suggested mowing height is 2-2½" for Kentucky bluegrass and perennial ryegrass fields and  2½-3” for tall fescue. Keep in mind that mowing at the lower level will increase turf density.

Sport Recommended mowing height
Multi-use Fields, low budget fields 2.0 - 3.0”
Football, Soccer, Lacrosse,
Baseball Outfields
1.5 – 2.5”
High Quality Soccer Fields,
Field Hockey, Baseball Infields
1.0 – 2.5”

Mowing frequency

The frequency of mowing will depend on grass growth rate and the time of season.  Typically Kentucky bluegrass fields will require mowing at least twice a week in the spring and fall.  In the summer when the growth of cool season grasses slows down, if not irrigated, you may only need to mow once every 10 days.

Delay mowing fields when the soil is saturated to avoid soil rutting which will create unsafe field conditions that will impact footing and ball response. Also avoid mowing fields that are showing signs of drought stress.

Mowing efficiency

No matter what mowing equipment you use be sure to have the blades sharpened every 10-12 hours of use.  Sharpened blades provide a clean cut and more attractive appearance.  Dull blades leave ragged edges which contribute to disease occurrence and can increase fuel costs 20%.

Mowing is an essential but time consuming management practice. According to the 2003 NYS Turfgrass Survey, schools use 57% of their labor resources to mow their properties and parks use almost 70%. Determining the best mowing equipment is a critical management decision when looking at reducing labor costs.

Both reel mowers and rotary mowers are used on sports fields. Reel mowers are used on high quality fields where a lower cut is desired. Reel mowers are more fuel efficient and more expensive than rotary mowers and require extra maintenance.  They do best on relatively smooth surfaces. Rotary mowers are very common, affordable and versatile. A clean cut can be achieved with sharp blades and a high blade speed. They can cut taller grass but sharp blades are essential.  Care should be taken to control discharge when using rotary mowers where people may be nearby and to avoid excessive clipping piles.

How much time will it take to get the job done?

It really depends on the equipment you have. To mow an acre of turf it will take more than 2½ hours with a walk behind with an 18” width, about 30 minutes with a 60” riding mower and less than 10 minutes on a gang mower with a 20’ width.

Floyd D. Perry, well-known professional sports field groundskeeper, uses the following process to calculate how much time it will take to mow an acre:

  • Hours to mow an acre x 60 minutes = minutes to mow an acre
  • Use the factor 108.9 which includes the acres per hour dimension and a 10% time factor for turning at the end of swaths.
  • The mowing speed equals the miles per hour rating at the recommended mowing gear or the usual ground speed.

Example:

  • The normal, safe mowing speed of a ride-on mower is 3.5 mph. Assuming the mower deck width is 38 inches; multiply 3.5 times 34.2” (9/10 of 38”).  The product is 119.7.
  • Divide 108.9 by 119.7 and get the answer 0.909 or 0.9 hours.
  • Multiply 0.9 hours by 60 minutes to get the answer: 54 minutes to mow one acre.

Trouble shooting some common mowing problems:

Symptom Possible cause Correction
Brown, ragged blade tips
  • Dull mower injury
  • Sharpen blades
  • Replace blades as necessary
Brown, greasy spots or streaks
  • Leak in hydraulic system
  • Find leak and repair
Rippling or marcelling
  • Mowing too fast
  • Inform operator of proper mowing speed
    (check operating manual)
Brown grass, stems showing, no leaves
  • Scalping caused by mowing height too low, wrong mower used or excessive thatch
  • Readjust mowing height
  • Control thatch
Narrow strip of unmown grass
  • Damaged or nicked reel or bedknife
  • Grind or lap reel and bedknife until nick is removed.
  • Replace if necessary
Uneven mowing
  • Reels not set properly
  • Check reel units
  • Set mowing height evenly

Mowing pattern

Sports field managers use skill and creativity to design field striping patterns that are visually appealing to spectators. The patterns give a professional look to the field and do not affect playability.  By mowing in different directions the leaves reflect light resulting in the appearance of dark and light stripes.  The rear roller or the cutting heads on reel mowers provide the best stripes. New rotary mowers that have now added rear rollers on each cutting deck can also provide the striping effect.

Mowing direction should be changed every mowing. Grass will lean or grow in the same direction it is mowed so changing the mowing direction each time you mow will avoid the undesirable streaking appearance. Varying the mowing pattern also helps prevent scalping high spots and wear in the wheel tracks.  

Watering

Why is water important?

Water has many important roles within plants and if the water content in the tissue should drop below 60%, the turf is seriously weakened and can die or go dormant.  Water is not only essential for growth but necessary for conditioning turf to handle and recover from stress caused by heavy use and harsh environmental conditions.

Supplemental water is necessary when natural rainfall is not sufficient to keep turf healthy after the soils have dried out. Temperature, sunlight, wind, humidity and natural rainfall are climatic factors that help determine the amount of irrigation that is needed.

Know your soil! soil texture (determined by the amount of sand, silt and clay in the soil) influences the amount of water that can be stored and available for plant use. For example, coarse textured soils such as sandy soils have poor water-holding capacity and will need to be watered more frequently than soils with more clay and organic matter which can hold more water.  Soils can differ from field to field. (See Soils section for more information.)

Keys to proper watering:

Irrigation should be supplied to replenish the amount of moisture lost.  Monitor conditions and water only when needed.  You can use a soil probe or moisture sensors to check the soil and see if it is wet to a depth just below the majority of the root system which is about 4-6". Also, turf takes on a dull bluish-gray color and its leaves curl when under severe moisture stress. If you can see your foot prints after walking on the turf and the leaves won't bounce back…begin irrigation. If the field is used before irrigation is applied damage will result.

How much?

Turf should receive about 1" to as much as 2” of water per week during the growing season. A rain gauge is a very inexpensive management tool that can be used to monitor rainfall. If rainfall provides ½" you will have to provide the additional amount of water depending on your soil and grass and evapotranspiratioin amount or ET. 

Turfgrass managers use ET to help determine supplemental watering needs. ET is the abbreviation for evapotranspiration, which is the combination of water lost from the soil surface and the water used by plants through the process of transpiration. Find rainfall information and ET values at the Forecast website.

How often?

Deep and infrequent watering, once or twice a week, is preferred unless you are on sand that needs more frequent irrigation.  Another time when more frequent watering will be necessary is at the time of establishment.  At this time it will be critical to keep the seedbed moist to ensure germination and may require daily watering, even several times a day.

Caution:

Never apply more water than the soil can absorb. Water that does not infiltrate into the soil will be lost  to evaporation or through runoff. There is an environmental risk to water quality when surface water runoff carries soil particles that contain adsorbed nutrients. When water bodies, such as lakes, estuaries, or slow-moving streams receive excess nutrients plant growth is greatly stimulated.   When dead plant material decomposes the dissolved oxygen in the water is reduced and this can cause other aquatic organisms to die. Therefore, proper water management and nutrient management are critical for protecting both soil and water resources and aquatic life.

Best time of day to water

Water in the early morning when the wind is calm.  This allows for adequate time for the turf blades to dry off before field use. Turf watered in the late afternoon or early evening remains wet longer allowing disease organisms time to penetrate turf tissue.

Be sure to finish watering at least 24 and preferably 48 hours before a game. Some managers water the field after the last practice or game if needed to help turf recover from the stress.

Watering during the growing season

Overwatering may lead to disease problems and thatch development. The better practice is to water deeply and less frequently which may be 1 to 3 times per week.

If the fields are not needed for summer sports and are in good shape, don't worry about supplemental irrigation and let the turf go dormant. Keep in mind that Kentucky bluegrass can survive in a dormant state for several weeks as long as the crown is hydrated so water ¼” to ½” every 4 weeks. Avoid traffic and management practices such as coring, verticutting or scarifying that may stress out the turf even more.

If the fields are in poor shape, summer watering may help them recover and get ready for fall use.

In preparing turf for winter keep the field on the dry side. The slight moisture stress actually enhances hardiness and winter survival. Do not, however, allow the turf to become drought stressed.

Watering systems

Portable systems: Many school and community sports fields do not have in-ground irrigation systems and rely on rainfall or above ground portable systems to provide needed water. Water reels, for example, are portable traveling irrigation systems that can be moved from the field to field once they complete the irrigation cycle.  All above ground portable systems will take time and labor to set up, move and monitor to ensure adequate and uniform coverage.

In ground systems: If you have an irrigation system check the heads to make sure they are level and running properly. Check the uniformity of your system by conducting a catchment test which will also let you know how long to run your system to provide the desired amount of water. Cans or collectors of the same size are spaced throughout the area being watered. After a period of 10, 20 or 30 minutes the amount collected is measured and noted to determine the amount of water applied and if there is even distribution so adjustments can be made.

Finally

Remember: All fields are not the same.  Soil texture, upcoming games and predicted weather will all factor into how much you will water and when. Avoid watering in windy conditions (>5 mph) because you will not get very uniform coverage. Over time you can gain experience with each field so you can determine the watering rate and timing based on your fields' characteristics.

Fertilizing

Building Your Fertility Program

Your goal as a turf manager should be to provide adequate nutrition that promotes turf density and in turn improves field safety and playing conditions. 

Many factors will influence the ultimate fertility program you develop including: grass species, soil type, time of year, intensity of field use, performance expectations, specific sport, budget, equipment, available labor, etc.

Some managers develop their sports field fertility program based on their experience, turf performance and generally accepted guidelines. 

However, routine soil testing that provides baseline information on the phosphorus, potassium status, pH and organic matter content coupled with tissue testing can add precision to your management decisions.

Soil testing

Soil testing is an important routine management practice and an essential tool when developing a fertilizer program that promotes good turf growth while protecting the environment.

For more information go to the Soil testing section. Keep in mind that turf will not benefit from the addition of fertilizer if there are adequate levels present in the soil and in the plant. Excess nitrogen applications will be harmful to turf growth and can have a negative environmental impact. Most New York soils have adequate levels of phosphorus so supplemental applications in most cases may not be necessary. When adequate soil levels of potassium (K) are present there is no benefit from applying more K. In fact high applications levels can inhibit root growth and excessive levels have been shown to increase the incidence of some diseases, like snow mold.

 

 

Necessary nutrients

Nitrogen (N), phosphorus (P) and potassium (K) are called “macronutrients” because they are needed by the plant in relatively large quantities.  Nitrogen (N) is the nutrient that primarily controls turf growth and density and is required in the largest amount. 

When adequate nitrogen is provided the turf will have a vigorous root system, high shoot density, maximum recuperative potential and tolerance to environmental stress. Also, varieties that have a color response to nitrogen will darken up when fertilized. Inadequate or low levels of nitrogen will reduce shoot density,  stress tolerances and ability to recover as fast from traffic damage, and favor weed encroachment and certain diseases like rust, red thread and dollar spot. Excessive amounts of nitrogen can be detrimental to the turf by reducing rooting, stress tolerance and wear tolerance. Excessive nitrogen can also increase thatch and favor diseases that thrive in high nutrient situations like snow mold, leaf spot and brown patch.

There is no reliable soil test for nitrogen so other factors are used in determining the amount of nitrogen that is needed. However, soils with more than 6% organic matter require less nitrogen. You can select nitrogen fertilizer sources that are water soluble and have quick release properties, fertilizers that have slow release properties or a combination of both.  See tables for advantages and disadvantages of different nitrogen sources. 

Advantages and disadvantages of nitrogen fertilizer sources

Nitrogen form Advantages Disadvantages

Quick release:

  • Urea
  • Ammoniacal N
  • Ammonium sulfate
  • Quick release, rapid response(within a week)
  • Minimal temperature dependency
  • Water soluble
  • Can be tank mixed (sprayed on)
  • Low cost
  • Short duration of response (peaks in 2 weeks, can last up to 6 weeks)
  • High salt index, can have foliar burn
  • Can leach or volatilize
  • Nitrogen losses can be greater

Slow release:

  • Sulfur Coated Urea   (SCU)
  • Polymer Coated Urea
  • Methylene Ureas
  • IBDU
  • Usually last 8-12 weeks, some 20
  • Low foliar burn potential
  • Reduced loss by leaching
  • Applied at higher rates less often
  • Higher cost per unit of nitrogen
  • Slow initial release rate
  • If bags damaged nutrients released
  • Microbial activity may be required for release

Slow release:

  • Natural Organics
  • Some contain other macro and micronutrients
  • Some improve soil properties
  • Some have disease suppressive activity
  • Slow initial release
  • Lower nitrogen content
  • Higher cost/unit of nitrogen
  • Nitrogen release is dependent on microorganisms, temperature and moisture dependent

Phosphorus 

Phosphorus (P) promotes rooting and is especially important in new seedings because it enhances establishment, especially with tall fescue. Phosphorus should be incorporated into the seedbed since it is not very mobile in the soil. Applications of phosphorus to established turf are rarely needed but applications of P may be necessary when overseeding. Soil test to determine needs.

The availability of phosphorus in the soil is influenced by pH. Phosphorus is most available at pHs above 6.5 so be sure to check your soil pH. 

Some common sources of phosphorus include superphosphate (16-21% P2O5), triple superphosphate (40-47%), Monammonium phosphate (48%) and Diammonium phosphate (46-53%).  A natural organic source is steamed bone meal (23-30%) and animal based composts.

Potassium

Potassium (K) promotes rooting, rhizome and stolon development and is said to improve heat, cold, wear and drought tolerance (although there is not enough research to back up this claim). It can help reduce some diseases such as leafspot, brown patch, red thread and dollar spot.

Potassium is very mobile in the soil and is easily leached in sandy soils.  So when soil tests determine potassium is needed it should be applied in smaller amounts several times during the year or applied in slow release forms especially on sandy fields. If soil test results are not available a minimum ratio of 2:1 (nitrogen: potassium) is desired. Common potassium sources include muriate of potash (KCL) with 60-62% K2O and sulfate of potash containing 50-53%.

Micro-nutrients for sports fields

Micro-nutrients are just important as macronutrients but are required in smaller amounts. They include iron (Fe), manganese (Mn), boron (B), molybdenum (Mo), zinc (Zn), copper (Cu), nickel (Ni) and chlorine (Cl). 
 
Sports turf managers either apply micro-nutrient packages based on soil test recommendations or because they are looking for “extra insurance”. Generally speaking, unless your soil has a very high pH (>8.0) or is very sandy in texture or low in organic matter it is unlikely that your soil will have a micronutrient deficiency.
 
Of all the micronutrients iron is the one we see the greatest response from greening.  Iron is an essential component of chlorophyll synthesis so it is not surprising to find chlorosis or turf yellowing in the youngest leaves if there is a deficiency. Regular applications of iron are usually essential for turf maintained on very alkaline (high pH) soils. Iron fertilizers can also be used to produce a dark green color without stimulating excessive leaf growth. A common practice for iron deficiencies is to apply a 1-2 ounce spray of ferrous sulfate per 1000 sq ft. Applications made when turf is growing rapidly enhance color for only 2-3 weeks, whereas applications made during periods of slow growth may last for several months. Organic products will provide a slower color response than inorganic sources like ferrous sulfate. Take care not to over do it! Excessive rates can cause a noticeable black-green color. When rates of inorganic sources were applied at greater than 5 lbs./acre, significant phytotoxicity (plant injury) was observed.

Before you consider using micro-nutrient packages as a routine practice, remember to check the soil pH. If it is in the 6.0 to 7.0 range micronutrients are usually found in sufficient amounts to support good turf quality. If the pH is high >8.0 sulfur can be used to lower the pH.  Use sulfur rates recommended by a soil test.  

Fertilizer terms

fertilizer bagComplete fertilizers will have the 3 most important macronutrients nitrogen, phosphorus and potassium (N-P-K) and will be stated on the fertilizer bag.  The numbers on the bag are always written in the same order and indicate the fertilizer analysis which is the percent (%) of nitrogen, phosphorus (as an oxide P2O5) and potassium (as soluble potash K2O) by weight. In a 100 lb bag of 20-5-10, 20% would be the nitrogen (or 20 lbs), 5% would be the phosphorus source (or 5 lbs) and 10% would be the potassium source (or 10 lbs).  The remaining material is needed to help spread the fertilizer or may just be part of the N, P or K and not added to make if spread better.

Another fertilizer term worth knowing is fertilizer ratio.  That is the proportion of the nutrients to each other. A fertilizer with the analysis of 20-20-20 has a 1:1:1 ratio as does 30-30-30.  A fertilizer with a 20-5-10 analysis has a 4:1:2 ratio.

A starter fertilizer is one that has a higher percent of phosphorus which is beneficial at the time of seed establishment and overseeding if soils are low in P. Examples include: 18-24-12 and 16-25-12.

Commonly used abbreviations and symbols

Unit Abbreviation or symbol Examples
Ounces oz. Apply 5 oz. each time
Pound lb. or # Apply 3 lbs. or Apply 3#
Cubic Yards cu. yd. or yd3 Apply 75#/ cu. yd. or Apply 75#/yd3
Square feet sq. ft. of ft2 Apply 5#/ 1,000 sq. ft. or Apply 5# 1,000 ft2
Acre = 43,560 sq. ft. A Apply 500#/A

 

Nitrogen sources

Although N, P and K are all important nutrients, more attention is given to nitrogen because it is needed in the largest quantity and will give the greatest response.  Applying nitrogen during the playing season will significantly improve turf quality, growth and recovery. Water soluble nitrogen sources provide rapid response within days or a week (depending on temperature) and will typically last about 2-6 weeks.  Slow release or controlled release nitrogen sources offer an extend period of nutrition and can last 8-12 weeks and some even as long as 20 weeks.

Natural organic nitrogen sources come from plant and animal by-products or waste products. They are typically lower in nutrients, have little burn or leaching potential and require warm moist soils for availability. The rate of nitrogen release from organic sources does differ. Research from North Carolina State University found that over a 10 week period, Nature Safe (turkey manure and feathers) released 70% of its total nitrogen, Milorganite (bio-solids) 60% and Bion (hog waste) 20%.  Products containing proteins (meat, blood, feathers, fish meal, corn gluten meal) release more nitrogen than previously digested sources such as bio-solids and animal wastes.

Characteristics of common turfgrass nitrogen sources

Fertilizer Source Nitrogen Content % Leaching Potential1 Burn Potential2 Low Temp
Response3
Residual Effect4
Inorganic*
Ammonium sulfate 21 high high rapid short
Organic - Natural
Bio-solids 6 very low very low very low long
Manures 3-10 very low very low very low long
Natural products 3-12 low-very low very low low-very low mod-long
Organic – Synthetic
Urea 45-46 high high rapid short
Sulfur coated urea 22-37 low low moderate moderate
IBDU 31 mod-low low moderate moderate
Methylene ureas 38 low low very low mod-long
Urea formaldehydes 38 mod-low low low long

* Ammonium nitrate and Calcium nitrate.

1 Leaching potential – likelihood of the fertilizer moving beyond the root zone due to its solubility.

2 Burn potential – likelihood of turf injury due to the salt concentration of the fertilizer.

3 Low temperature response – the ability of the fertilizer to have an effect under low temperature    (50°- 60°, for example in the spring when early green up is desired.

4 Residual effect – estimates how long the fertilizer effect will last.  For example, water soluble   (quick release) fertilizers are short termed lasting between 2-8 weeks whereas slow release  fertilizers may last up to 4 months or more.

Nitrogen timing and rates

When establishing a new stand of turf on sandy type soils apply 0.4 pound of a soluble nitrogen  per 1,000 sq. ft. or up to 1 pound of total nitrogen with fertilizers with at least 60% slow release nitrogen. If in 4-6 weeks the turf is not dense and it is before November 1st make another application at the same rate. If it is after November 1st wait until mid-May to make this application.

On non-sandy soils apply 0.7 pound of a soluble nitrogen  per 1,000 sq. ft. or up to 1 pound of total nitrogen with fertilizers with at least 30% slow release nitrogen. If in 4-6 weeks the turf is not dense and it is before November 1st make another application at the same rate or less.  If it is after November 1st wait until mid-May to make this application.

Fertilizing established turf

Understanding how cool season grasses grow and develop will help in understanding the strategy behind specific timing of established turf.

Focus your fertility program on building a healthy root system. Sixty percent (60%) of your fertilizer applications should be made in the fall when the roots can benefit from it the most. An extensive root system is better able to survive stress next summer.

How grass grows

When a fall application was not made and spring sports are planned a light nitrogen application can be done in early spring after April 1st. Heavy spring fertilizer applications, however, lead to excessive shoot and leaf growth and poor root growth.  This leaves the turf less likely to handle the harsh summer conditions.

Unless you are irrigating the turf there may be little or no need to fertilize in the summer if it is dry. If an early summer application is desired to repair damaged fields from spring use, select a slow release type like a natural organic source which release nitrogen slower than conventional water soluble sources.

A late summer fertilizer application (mid-August) is important because it promotes recovery from the summer's drought and heat related stress. Select a fertilizer with a 50:50 water soluble N: slow release form and apply at the ¾ -1 lb nitrogen rate per 1000 sq. ft.

Early fall fertilization (September) increases turf density by encouraging the production of new tillers, rhizomes and stolons and more shoot growth from existing turf. The production of carbohydrates at this time will help turf survive the stresses of winter and encourage spring growth.  October fertilization will maximize turf growth and recovery from fall sports.

Fertilizing turf when the soil is not frozen and when foliar growth slows down (when air temperatures are <50° for 10 days) contributes to significant root, rhizome and stolon growth.

Also, turf color is extended into the late fall and early winter and early spring green up is promoted. Be careful, however, with late season nitrogen applications on sites with ground water issues, like Long Island. Follow state and local laws on the last date to apply fertilizer which may be November 1st or November 15th in your area. If you choose this option select a nitrogen source that is not temperature dependent, like IBDU and SCU and apply at the ¾ lb. rate or urea at the ½ lb. per 1,000 sq. ft. nitrogen rate. 

Sample fertilizer program for football fields

Situation: no spring sports on this field
Minimal management field rates are bolded
High management fields rates are in red

Timing Nitrogen rate
per 1,000 sq. ft.
Nitrogen
source
Comments and strategy
Before April 1st     Do not apply fertilizer.
Early spring     If late fall fertilization applied previous year, early fertilization may not be needed
Mid-late May 1#
1#
50% water soluble or use a 100% organic source Warm soil temperatures release nutrients.
Organic sources build up soil nitrogen and feed microorganisms.
July     No need to fertilize especially if fields are not irrigated.
Mid-August 1#
1#
50% water soluble Apply just before the season begins.
Mid-September 1# 50% water soluble  
Mid-October ½ # 100% water soluble  
November     New York State or local laws may prohibit application of fertilizer at this time.

 

Cultivating

Why are fields routinely cultivated?

Cultivation methods, including coring, slicing, spiking, drilling, vertical mowing and injecting water, are used to remediate compacted soils, aid in overseeding and help manage thatch. Foot traffic and vehicular traffic cause soil compaction, especially on fine-textured (clayey) soils which results in surface puddling and runoff. Compaction reduces access to water, nutrients and oxygen necessary for plant growth. Compaction also makes it difficult for added amendments like lime and fertilizer to reach the root zone.

Strategies to reduce soil compaction and improve better surface drainage and gaseous exchange for enhanced root growth include:

  • Limiting vehicular traffic or using special turf tires when on fields that are prone to compaction.
  • Avoiding field use when soils are saturated.
  • Not irrigating 24 to 48 hours before a game or major event.
  • Limiting the number of games and events on your fields, especially fields that are prone to compaction.
  • Setting aside one field that will serve as your game or showcase field and not allowing practice on it.

Always make multiple passes to impact larger surface area. Do not aerify or cultivate the soil when the turf is under stress or when the soil is too wet (which would destroy soil structure) or when the soil is too dry (which would make pulling cores difficult and could harm turf roots). Usually one to two days after a normal rainfall on a moderately well-drained soil would be good timing for this practice.

Cultivation methods

Coring in the early fall can increase the opportunity for annual bluegrass (Poa annua), invasion. However, a Penn State study found that there was less Poa invasion when solid tines were used versus hollow tines, so use solid times at this time.

Coring, slicing, spiking, drilling, vertical mowing and injecting water into the soil are methods used to deal with soil compaction.

Core cultivation (often referred as aerification) removes a core of soil, leaving a small hole which allows for better water and air movement into the root zone. Fertilizer and amendments can more easily reach the root zone resulting in a deeper more extensive root system.

Coring with hollow tines or spoons removes a soil core which can be collected or left on the soil surface. Tines can be placed in various spacings and can range ¼"- ¾" in diameter and penetrate the soil 3-6". Keep in mind that the size and spacing of tines influences the area of impact. For example: ½” tines spaced on 2” centers will impact only 5% of the surface whereas 5/8” tines spaced on 1”x 2” centers will impact 15% of the surface.

Ideally, each coring should impact at least 10% of the turf surface which is about 10 to 15 holes per square foot.

Soil cores left on the soil surface should be allowed to dry and then dragged with a mat to break them up. This process mixes soil into the thatch layer where microorganisms can begin to decompose the thatch. This would be a good time to apply lime or fertilizer if needed.

Solid tines disturb the soil surface less than coring, but they compact the bottom and sides of the holes.

Spiking uses solid tines to punch holes into the soil when less soil surface disruption is desired. This action actually causes compaction at the bottom and sides of the hole and is not as effective as hollow tine coring in improving soil physical properties. However, it is effective on heavily compacted areas especially when improving soil aeration is desired.

Shatter tines are used to fracture hardpans in the subsoil.

slicerSlicing equipment can be used when overseeding to provide a place for seed to germinate.

Slicing cuts a narrow slit into the soil and encourages lateral growth of Kentucky bluegrass. Slicing equipment can also be used when overseeding to provide a place for seed to germinate.

Deep drilling can create channels to a 12" depth with metal bits up to 1" in diameter. This kind of cultivation is often used to improve subsurface drainage on highly compacted areas of football and soccer fields. Fields may benefit from deep tine aerification once or twice a year if the drill goes deep enough to go below the depth of compaction.

Vertical mowing uses blades that cut vertically into the turf canopy to sever lateral stems. This practice helps to increase turf density, remove thatch at the soil surface and prepare the turf for overseeding.

Injecting high pressured water into the soil through small-diameter nozzles opens channels for roots to grow with limited disruption of the surface.

Select the best cultivation method that matches your goal. Some methods should be used when fields are not in use while others can be used during the playing season.

Cultivation practices for use between playing seasons

Adapted from Dave Minner, Iowa State University
Match cultivation goal (below) with the tool (right) Hollow
tine
4-inch
Solid
tine
4-inch
Hydro-
jet
Shatter
tine
4-inch
Shatter
blade
Verti-
drain
Drill &
fill
Slicing Small
slicing/
spiking
Vertical
mower
Change soil type in top 4 inches
by removing soil and back filling
with amendment
X             X    
Create large and deep holes or
channels that can be back filled
with a soil amendment
              X    
Remove surface soil layer that
was attached to sand-sod during
sand-based field construction
X             X    
Promote deep rooting,
8 inches or more
    X   X X X X    
Maximum removal of
water puddles
        X X X      
Aggressive fracturing of hard
ground (surface to 6 inches deep)
      X X X        

Cultivation practices for use during playing seasons

Adapted from Dave Minner, Iowa State University
Match cultivation goal (below) with the tool (right) Hollow
tine
4-inch
Solid
tine
4-inch
Hydro-
jet
Shatter
tine
4-inch
Shatter
blade
Verti-
drain
Drill &
fill
Slicing Small
slicing/
spiking
Vertical
mower
Increase initial water infiltration rate 
with minimal disturbance to surface
X X X X X X     X  
Plant seed with minimal disturbance
to grass and soil stability
  X   X            
Encourage lateral growth
of sod forming grasses
                X X
Fracture hard skin infield,
drag surface and begin play
      X            
Fracture hard grass fields       X X X        
Fast operation over field         X          

What about frequency and timing?

The benefits of cultivation are short-lived and therefore should be done frequently. High traffic areas should be cultivated 6-8 times per year. A suggested coring schedule could entail heavy coring in the spring prior to fertilization, light coring in late summer and early fall before fertilization and heavy coring at the end of the season. At that time you can collect the cores and let the holes remain open for freezing and thawing action.

Overseeding

Overseeding is the periodic application of seed to an existing turfgrass stand to improve turf density. A widely accepted concept is that 25 events on a native soil football field is the limit for optimum turfgrass recovery. The grass cannot recuperate quickly enough when used for games, practices, gym class and other school activities. So overseeding must be done on a routine basis on high-use fields if there is any chance of providing a dense, more uniform, and safe playing surface.

Image: Test strips of perennial ryegrass aggressively overseeded for just one year surrounded by crabgrass.

Grass species selection

Selection depends on several factors including: overall goal of field quality, resources for follow up maintenance, irrigation capabilities, etc. Review options in the Grass section. For added insurance always select those varieties that have superior wear tolerance. For detailed cultivar performance information check the National Turfgrass Evaluation Program website.

Consider aggressive overseeding

An excellent time to overseed is right after aerifying or cultivating your field.

Research at Cornell and other universities found that overseeding weekly under high traffic conditions with either perennial ryegrass or tall fescue provided excellent season-long turf density. Perennial ryegrass was able to maintain almost 90% density and the tall fescue plots had between 70% and 80% density at the end of the study.

Note: Overseeding with Kentucky bluegrass (KBG) proved completely ineffective under regular traffic most likely due to the long germination and establishment requirement.

The non-overseeded plots were less than 50% covered with turf and in some cases up to 20% weeds.

Routine overseeding provided a dense, more uniform, safe playing surface.

When to overseed

Involving coaches and players not only reduces labor needs during difficult economic times, but also emphasizes that everyone has a role in maintaining dense, more uniform and safer playing surfaces.

In-season broadcast seed over high use areas and allow athletes to cleat-in the seed. You can also fill in divots with a mixture of soil and perennial ryegrass seed a few days in advance of a game or expected field use. Mix seed with soil (1 part seed to 10 parts soil) to make the divot mix. Involve coaches and players to help repair the field after every heavy use.

After the fall season is over, fields are worn thin creating an ideal seedbed for overseeding KBG. There also is little competition from remaining perennial ryegrass or other species.  Aggressively core, drag the field and broadcast KBG seed When the soils warm up in the spring the KBG will out compete other species in the stand. This is a particularly effective strategy to improve the KBG stand when the late fall seeding has 2 to 3 months to establish without play and no play is planned for the following spring.

Overseeding rates for quick cover

Species and Mixtures Pounds of seed per 1,000 sq. ft.
Kentucky bluegrass (use several improved varieties)

 

2½ - 3½
Perennial ryegrass (use several improved varieties) 10-15
Tall fescue (use several improved varieties) 10-15
Kentucky bluegrass/perennial ryegrass (80:20 mixture) 3-4
Tall Fescue/Kentucky Bluegrass (90:10 mixture) 10-15

Worth the investment!

Some budgets are large enough to pay for overseeding the entire field periodically. If having better coverage and less weed pressure are your goals then the benefits of an aggressive overseeding program will outweigh the cost.

But what if you  had limited resources? You could concentrate your overseeding program in the areas that receive the most traffic (goal mouths, or between the hash marks and 20 yard lines) to reduce the cost. The chart below estimates the cost of an aggressive overseeding program when focusing on only high use areas.

Cost of aggressively overseeding high use areas of sports fields with perennial ryegrass at 2 lbs. of seed per 1,000 square feet

Field Type/
High use area in sq. ft.
Seeding Rate Cost Results
Pound of seed Weekly cost 13 week season
Soccer Field
22,000 sq. ft.
2 lbs. per 1,000 sq. ft. $2.00 $88 $1,144 Better turf density/coverage.
Less weed pressure to deal with.
Football Field
16,000 sq. ft.
2 lbs. per 1,000 sq. ft. $2.00 $64 $832

But what if you had limited resources? You could concentrate your overseeding program in the areas that receive the most traffic (goal mouths, or between the hash marks and 20 yard lines) to reduce the cost.

Preparing for overseeding

  • Mow the grass short.
  • Aerify the field by punching at least 20-40 holes/ft2 with the largest hollow tines available and make several passes.
  • Drag the field to break up cores and provide a desirable seedbed.
  • Apply the seed with a drop seeder and make several passes to ensure a uniform seeding.
  • Do not allow the seedbed to dry out. Water to keep the surface moist.
  • After the grass has germinated, apply ½ lb. per 1,000 sq. ft. of a nitrogen fertilizer containing at least 60 percent slow release N if your soil is sandy to minimize leaching and water pollution. If your soil is a non-sand soil apply ½ lb. of a nitrogen fertilizer containing at least 30 percent slow release .

Topdressing

Topdressing is the application of a uniform thin layer of soil or finely granulated organic materials applied over the turf surface. It is used to level the playing field when minor variations or depressions are apparent, help to amend physical soil properties and create a better growing environment for the turf and help reduce thatch.

If you have access to a readily available topdressing material, the necessary application equipment and a budget that can afford this practice, topdressing can be an important part of your management program.

Timing and frequency

When conditions warrant it topdressing is done as a routine practice 1-2 times per year when the turf is actively growing, for example, in late spring, early fall and/or in late fall after the playing season.

Frequent applications can, over time, actually modify the soil profile. It is often combined with core cultivation practices.

Topdressing materials

Selecting the correct topdressing material is critical and depends on the purpose of the topdressing. The chosen topdressing material must be consistent in type and particle size and available for future applications. Variations in particle size can lead to layering which will disrupt drainage and rooting.

Material Use Characteristics and Application Tips
Soil All When soil modification is not needed the existing soil or one similar in texture can be used. Pull cores, allow cores to dry on the surface and then drag to have soil fill in aeration holes.
Sand L,C,P

Can use 100% sand should be angular or medium coarse. Make sure the sand source will be available for future use.

Can use a mix with 80% sand and 20% organic matter. The mix should not contain more than <5% fine gravel and <10% silt + clay or 2-5% very fine sand, 2-5% silt, 2-5% clay.

After applying the topdressing material, first pull the drag mat making small circles then in large ovals so the material can filter into the aeration holes and also provide a level field.

Compost All Should be mature, screened, have a fine particle size, be within the pH range of 6.5-8.0 and have a low salt content. Compost should be tested. Apply no more than ¼ inch per application.
Crumb Rubber   Should have a small particle size: 0.05-2.0 mm. Apply at a ¼ inch depth per application until a cumulative depth of ¾ -1 inch depth is achieved over time. This material is expensive.

Uses:

  • L: to level minor depressions
  • T: to reduce thatch
  • C: to reduce hard compacted soils (following a cultivation practice)
  • P: to improve aeration and drainage
  • S: to improve seedbed for overseeding

Amount needed

The amount of topdressing material needed will depend on the purpose of the topdressing. A light application, a 1/8" – 3/8" layer which is about ½ - 1¼ cubic yards for each 1,000 sq. ft., is usually used when seeding or overseeding.

Topdressing to amend the soil to relieve compaction will require a heavier application, enough to fill the aeration holes. To change the soil profile by actually building a sand cap will take much more material.

Topdressing amounts

Approximate Depth (inches) Approximate Amount Needed cubic yards/1,000 sq. ft.
1/8 0.4
¼ 0.8
3/8 1.2
½ 1.5
¾ 2.3

Topdress with sand to level minor depressions, improve aeration and drainage, and reduce compaction following aerification.

Several approaches to using sand to improve drainage include:

A short term approach involves punching holes in the soil using a core aerator, spiker, deep tiner or verti-drain to allow water and air to enter the soil. This practice will only last a week or two and the holes will seal over creating the previous situation.

A sand-cap can be built slowly over time by applying a 1 inch depth of sand over a 3½ month period with the goal of building a 2 inch layer within 2 growing season. See Sand Cap Build-Up Systems for Michigan High School Fields.

Once that level is reached an annual application of ¼” of sand along with core cultivation and/or vertical mowing will mitigate organic matter accumulation.

Rolling

Rolling Sports Fields

Rolling is used to smooth out uneven surfaces caused by heavy traffic and can be used to press uprooted or heaved plants back into the soil to prevent desiccation. Rolling can produce a firm surface to provide a “faster” surface. Like all field practices it must be done correctly so it won’t do more harm than good. If the soil is too dry there will be no response to the rolling and if the soil is too wet excessive soil compaction can occur.

Rollers typically range from 300-2000 pounds or more. The maximum weight which should be used for a native soil is one ton (2000#). The amount of stress a particular soil can withstand depends upon its ability to resist compaction which depends upon soil texture (sand or native soil) and moisture content. So make sure the roller is not too heavy for your situation or it can rut up and over compact the field. 

Also, the need for rolling will depend on the specific situation and will vary from field to field. If rolling needs to be done, it should be done in 2 directions.

Facts and tips

Provided by Dave Minner, Turfgrass Extension Specialist, Iowa State University:  

  • Rolling does not improve turf quality. In fact, over use results in turf thinning and quality is significantly reduced.
  • Soils that are wet and/or frozen are susceptible to surface compaction. Over use of rollers will also result in surface compaction. It is critical that rolled fields are regularly aerated. 
  • Soils that are too dry will not benefit from the impact of rolling. Furthermore, if the turf is wilted or dormant it will be severely stressed and may die. Rolling should only be carried out if grass is actively growing. 
  • Fields with 100% grass cover and a moderate thatch layer are less likely to be affected by rolling as a method to increase field "speed". 
  • Never roll fields that have disease problems, particularly infectious diseases like gray leaf spot, pythium, or brown patch.

Rolling Frequency

The decision as to how often to roll a field should be made by the field manager and coach on a field-by-field basis. Factors to consider include: athlete safety and playability, soil moisture, recovery time and turf quality.  

Remember, rolling should only be carried out "as-needed", not routinely. This may be once per year in the spring (after winter soil heave) or several times during the playing season to keep the field safe and playable if grass cover is lost. 

When rolling sports fields that are already prone to compaction remember to always counter-balanced rolling by conducting a strong aeration program.

 

 

Managing Thatch

Thatch is the accumulation of undecomposed or partially decomposed organic matter (living and dead roots, crowns and stems of grass) that is found at the soil surface below the grass blades.  When organic matter accumulates faster than it can be decomposed, thatch results.  A thatch layer is good if it is less than ¾”because it can absorb some shock, provide some cushioning and minimize to some degree the potential for player injury.  However, levels greater than ¾” can cause shallow rooting and negatively affect turf health.

Excessive thatch levels make it difficult for water, fertilizer and pesticides to reach the soil.  Yet the thatchy area is ideal for pathogens to thrive and when the turf is stressed the likelihood of patch diseases, for example summer patch, increases. Also when the thatch layer is high it can elevate the crown which can be scalped during mowing.  When thatchy turf dries out it is very difficult for the water to infiltrate into the canopy and reach the soil, thus creating “hydrophobic soils”.

Some organic matter accumulation is normal, but grasses such as Kentucky bluegrass are thatch producers.  Improper pH, compacted soils and poor drainage encourage thatch build up. So thatch management strategies include: keeping the soil pH in the proper range,  core cultivating and topdressing – all practices within the turf manager’s control.

Field Scheduling

It would be ideal to have at the start of each sporting season fields with 100% turf coverage and have all the plants at least four months old.  This is the ideal and may not always be attainable.

Fields will show distinct wear areas after 10 events (games, practices, etc.) and after about 25 the field appearance will be significantly reduced.  The loss of that protective mat of vegetation will be gone between 25-50 events and the soil will be exposed ready to turn into a muddy mess when rained and played on.  What can a manager do to limit over-use which creates unsafe and poor field conditions?

The grounds manager must be able to communicate to and develop a strong working relationship with coaches, administrators and field users so policies can be developed regarding field use and field scheduling. Many factors go into developing a field schedule especially at a multi-use facility. The type of sports, intensity of traffic, type of grass, field conditions at the time of play, the necessary time for the field to recover and essential management practices all impact field scheduling. All field users need to understand the challenges of maintaining fields in good safe condition when unrealistic expectations are made. Cooperation and communication are essential.

Some helpful tips:

  • work to develop mutual respect and realistic goals so policies can be established and honored
  • restrict use of fields when conditions are wet and would create unsafe playing conditions
  • rotate areas of play to allow time for recovery
  • find alternative areas for some of the activities (for example band practice)
  • allow newly seeded areas to become established before use
  • allow turf to recover from winter dormancy before using

Arrange for a meeting with key individuals prior to the field season to discuss components of the field use policy. Some managers have the authority to close fields if not in playable conditions and can levy fines.

Ultimately, everyone will learn that if field use guidelines are not followed and fields are used during rainy periods permanent damage can result and expensive repair work will be necessary.