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"Minimum" Maintenance Is "Required" Maintenance: Natural Grass Sport Fields

INTRODUCTION: To slow / stop the spread of Covid-19, "Entertainment and Recreation Venues" are closed across the USA. Venues that include Stadiums, Sports Complexes, Schools. Even in Parks, no organized sports are allow. All this has brought Natural Grass Field usage to a FULL STOP.

With Venues forced to closed because they are deemed "Non-Essential Business" and field use stopped - What does that mean for Natural Grass Field maintenance? We discussed that last week in this piece on "COVID-19 and Natural Grass Field Maintenance". As part of commercial and public infrastructure maintenance, Natural Grass Field maintenance (and essentially ALL residential and commercial maintenance) can be considered "Essential".

But as the pandemic spreads, Government intervention is growing. That is expanding the "gray" area on what is "Essential" and "Non-Essential", even when it comes to Natural Grass Field maintenance. What is NOT "gray" is the Government's desire to reduce worker's exposure to COVID-19. No matter what a business's legal interruption on being "Essential" or "Non-Essential" - what is very clear is the responsibility of each and every Employer to protect their employees. And the responsibility on each and every Manager / Supervisor to ensure that their employees are being kept "safe" from exposure to COVID-19.

The "gray area" is indeed expanding though. Yesterday (Monday, March 30), Maryland expanded on last week's order that closed "Non-Essential Business" to a new STAY AT HOME order. Opposite of PA and VT, ALL Commercial and Residential Construction continues to be "Essential" business as part of the STAY AT HOME order. So if you are doing renovation or construction on a field in Maryland, technically that doesn't have to stop. Landscaping Companies are also considered "Essential" as part of the STAY AT HOME order. But as part of the STAY AT HOME order, MD's Executive Branch offered a clarification for "Non-Essential Businesses" that are closed (including Entertainment and Recreation Venues). The "Non-Essential" businesses can continue "Minimal Operation" to "maintain essential property". Maintaining Natural Grass Fields is absolutely "maintaining essential property". Again, the "Minimal Operation" does not include Construction or having a Landscaping Company doing work at the "Non-Essential" Entertainment and Recreation Venue. So the "gray" area grows.

But in the spirit of cooperation, understanding the Government's goal is to look out for and protect us all and the long-term viability of our society and businesses, we want to take a look at the concept of "Minimal Operation" for Maintenance of Natural Grass Fields. What does a "Minimal" maintenance operation look like?

The dictionary defines "Minimum" as "the least or smallest amount or quantity possible, attainable, or required."

REQUIRED. Minimum Maintenance is doing what is REQUIRED, and nothing more.

In that spirit of cooperation, let's now take a look at "Required" Maintenance for Natural Grass Fields in the Spring and Early Summer Season.

To start, a few important things in reference to Natural Grass Field maintenance:

A. Spring is likely the most important maintenance period of the year for Natural Grass Fields

B. Outside of MLB, NFL, and MLS (and even including some of them), a majority of Natural Grass Field maintenance operations already run at the "Minimum" level. Much like farming / agriculture, Sports Field Managers are A) limited by budget, so they B) strive to keep inputs as low as possible. If a Natural Grass Field has something getting done to it - it is because it is REQUIRED. State Fertilizer laws, Federal Pesticide laws, and Facility Budget offices all hold maintenance operations accountable to minimum or REQUIRED use. And Sports Field Managers expect it from themselves as stewards of the environment.

C. Natural Grass Field maintenance "requirements" are based mainly on 4 things:

1. Season: Spring, Summer, Fall, Winter

2. Mother Nature AKA " Weather"

3. Data from things like Soil Nutrient Testing and Field Surface Testing

4. Amount of traffic on the field (field use)***

The last point (C-4) will be the closing piece of this discussion. Spring Maintenance requirements are based more on "Seasonal" requirement than traffic / use requirement. Following the Spring Maintenance, there can be / will be reduced requirements on the Natural Grass Field Maintenance operation compared to a "regular" year of regular or high-use. In Closing, we will explore those potential reductions. But first, an exploration of "Required" Spring Maintenance for a high-use Natural Grass Field.


"REQUIRED" Natural Grass Field Maintenance: "Spring" Into Summer


Spring maintenance builds the entire year's foundation with a Natural Grass Field. If spring maintenance plans are scaled back or delayed, the impact on field quality, durability, and safety will be evident for at least 18 months (well into the 2021 growing season). Problems / challenges that arise from scaled back or delayed maintenance will require more spending ($) than the "regularly scheduled" maintenance itself will cost.


Spring is a time of renewal and excitement, not just for humans - but grass too. Sun intensity increases and ambient temperatures rise to increase soil temperatures and "wake up" grass - Kentucky bluegrass (Blue) and Perennial ryegrass (Rye) is starting to grow actively

- Southern regions have Bermudagrass (Bermuda) now beginning to come out of winter dormancy, with Central regions experiencing Bermuda green-up sometime before mid-May.

1. With the grass "waking up", now (Spring) is the time when grass recovers / "fills-in" areas damaged by fall / winter / early spring play

- Blue is pushing rhizomes to spread out and fill-in

- Increasing soil temperatures will allow Blue and Rye seed to germinate from seed

- Between now and July, Bermuda will be regenerating / pushing stolons across the soil

2. ALL of this recovery, from green up to to seeding to regeneration, only happens if / when Spring maintenance takes place on-time

- Sun intensity and summer heat put Blue and Rye plants under extreme stress that limit recovery from June 1 until September 1

- Seed planted after May 1 most likely will not survive summer stress and / or require extra pesticide and increased plant feeding w vitamins, amino acids, and anti-oxidants

3. Bermuda thrives during summer heat, but a strong spring start is essential

- Bermuda needs full density during summer to utilize long summer days to carbohydrate load for fall growth + spring green up

- Bermuda experiences stress in the fall and spring because of lower sun intensity with shorter days and the sun lower in the sky

- Without proper summer carbohydrate loading, Spring 2021 green-up will be delayed

4. Weeds and insects (pests) are also starting to "wake up" and grow during Spring. Without regular spring maintenance, the impact of weeds and insects will be dramatically higher

- #1 defense against pests is a strong, healthy, dense stand of grass


#GrassCanTakeMore® Puzzle from NGAG

Natural grass field maintenance

works as a puzzle. As an assembled puzzle is success - each field maintenance practice is REQUIRED to achieve success.

The key pieces of the maintenance puzzle are:

- Mowing

- Seeding / Sprigging / Sodding

- Aeration (Soil De-compaction)

- Plant feeding (Fertilizer / Bio-stimulants)

- Water Management (Irrigation / Drainage)

Pest Control is also KEY, based on need, as part of Integrated Pest Management (IPM). Pesticide Applications and IPM are specific to individual facilities in philosophy and regulation. In respect of that, the 5 key pieces of maintenance all work to reduce or eliminate pesticide use



Mowing is the most fundamental piece of maintaining natural grass. During this time period of spring green up, it is VITAL for grass fields to stay on their regular, as-needed mow schedule*

- Initial spring mows, at lower height, cut off brown tissue to expose green leaves to sun

- Sun on green leaves allows photosynthesis

(energy production) for growth

- Sun on green leaves increases canopy temperature & growth (darker color, more heat)

- Regular mowing promotes Blue & Bermuda to push sideways / fill-in / become more dense

- Increased density fills thin spots, increases durability, and reduces weed pressure

* Mowing schedule is dictated by mowing height and grass growth, driven by spring ambient temperature, soil temperature, feeding, rainfall

Minimum Spring Mowing

  • Blue / Rye @ 1" - 1.5": 3x / wk w Reel Mower or High-Speed Rotary Deck Mower

  • Blue / Rye @ 1.5" - 2": 2x / wk w ZMower type mower

  • Bermuda @ 1/2" - 3/4": 3x / wk w Reel Mower (as dormancy breaks)

  • Bermuda @ 3/4" - 1.2": 2x / wk w High-Speed Rotary Deck Mower (as dormancy breaks)

* Rye that has been seeded into Bermuda for winter color needs even more mowing to "scalp" back / down the Rye. Keeping the Rye mowed down / cut back allows sunlight to get to the Bermuda to encourage and support green up and growth up through the Rye

- During suspended play, many Sports Field Managers are utilizing vertical mowing (verticutting), fraze mowing, or using a herbicide to speed the Rye to Bermuda transition



Before the pandemic shutdown began, fall / winter / early spring play has all already taken place. Spring is the time for repair & recovery to take place following that previous play.

  • Blue (Kentucky bluegrass) requires seeding, sodding, or plugging worn area

  • Regular mowing + aeration + plant feeding will promote Blue to re-generate / spread to fill-in some damage / wear, but more plants are required as spread is slow

  • Rye (Perennial ryegrass) requires seeding or sodding, as it's spread is limited

  • Bermuda spreads very aggressively. But in areas that have worn through the stolon networks, sprigging or sodding will be required

A. Seeding / Sprigging / Sodding is not "failure" - it is regular maintenance that helps high-use natural grass fields recover faster to stay strong, resilient, and safe to meet the needs of the users. Re-establishing grass w no current field use will increase field durability in the future.

B. It is important to utilize Superior Grass Varieties for resilience and durability on high-use natural grass fields. If Superior Grass Varieties are not utilized, success can not be achieved

- Blue Varieties*: Barvette, Barseratti, Barrister, Hampton, Fullback, Bluebank, Noble, SPF30

- Bermuda Varieties*: Tahoma 31, Latitude 36, Northbridge, Celebration

* These varieties have been utilized and tested by NGAG. Others may be considered Superior, based on NTEP trials



The most consistent challenge facing high-use Natural Grass Fields is soil compaction. Issues from soil compaction plague over 90% of the grass fields NGAG has done Field Performance Testing / data analysis on during our 5 years of support work. Soil Compaction reduces and / or eliminates the air space in the soil, making aeration (both Surface & Sub-Surface) essential to increase soil air space during spring maintenance. Increasing air space is imperative to:

A. Allow grass rhizomes sideways and roots to grow down in the softer, air-filled soil

B. Support establishment of seed / sprigs / sod in areas that are thin due to compaction

C. Stimulate soil microbial activity (microbes need air too!) to break down organic matter to release nutrients and to support nutrient uptake by the grass roots

D. Reduce irrigation need during summer, as 1) water can soak in to a less compact soil easier and 2) healthier grass w deeper roots requires less water

E. Increase vertical drainage to allow the field to dry faster after rain

F. Decrease weed pressure as strong, dense, healthy grass can outcompete weeds

G. Improve Field Surface Safety, as surface hardness goes down / energy is absorbed better by a less compact soil

Given these numerous points of importance, aeration during Spring Maintenance is imperative for the health of the grass plants. In this unique time with no play, spring maintenance provides the opportunity to not only alleviate soil compaction - but potentially for the 1st time get out ahead of the impending high-use coming to all natural grass fields very soon (hopefully!).

In Spring Maintenance (as in all times of maintenance), there are 2 types of compaction relief:

Surface Compaction

Surface compaction builds up in the top 4" from consistent foot traffic during field use. Mowing also adds to surface compaction, in particular if mowing takes place when the field is wet (from rain OR irrigation). The reduction of Surface Compaction comes from opening / softening / impacting the most surface area possible.


- VertiCore (shown in photo) w 5/8" solid tines poking holes 2" x 2" = 8% surface impact


- Old-style spin open-spoon w 3/4" hollow tines poking holes 6"x 5" = < 1% surface impact

The 2"x 2" spacing is FAR MORE IMPACTFUL, therefore reduces surface compaction more*. This type of surface area impact can be achieve by:

- John Deere Aercore

- Toro ProCore

- Redexim VertiCore (pictured)

- Toro 687 Slicer

- Redexim Level Spike

- Many other slicers, depending on the blade spacing (slicing is VERY impactful)

* Data from NGAG Field Surface Testing & "The Long-Term Effect of Open-Spoon Aerification On Plant and Soil Properties" (By Dr. Chase Straw et all)

Sub-Surface Compaction

Sub-surface compaction is from initial field construction. Once relieved completely in the top 10 - 12" (root zone of the grass), sub-surface builds up slower over time if surface compaction is managed properly (especially on sand base fields). On fields that are used more than 12 hours / week, surface aeration needs to take place every 2 weeks to keep from accumulating sub-surface compaction in the high-use areas of the field. That amount of surface aeration does not take place in most maintenance programs, meaning that sub-surface compaction needs to be addressed at least 2x / year (spring & early fall at a minimum) using:

- Deep-tine Aerator: Redexim VertiDrain / Wiedenmann Terra Spike / Toro Soil Reliever

- Linear De-compaction Aerator: Redexim VertiQuake / Imants Shockwave

- Air Injection De-compaction Machine: Air2G2 (Shown below)


PLANT FEEDING (Fertilizer / Bio-Stimulants)

Plant feeding is a critical part of Spring Maintenance for Natural Grass Fields. Supplemental nitrogen fertilizer and certain advanced bio-stimulant products, in combination with low spring mowing, help "jump start" grass growth before soil temperatures reach a point that existing soil nutrients become available. This jump start is essential, and dramatically impactful, in driving grass growth and recovery to be out ahead of pests waking up and starting to populate.

When soil temperature rise, in combination with soil de-compaction, microbes begin work and all fertilizer applications can be based on Soil Nutrient Testing data.

Nitrogen Fertilizer

Nitrogen is an essential macronutrient to sustain growth in a grass plant. Too much nitrogen can be more detrimental than too little for overall grass health and strength. To avoid excessive nitrogen, Soil Nutrient Testing technology graphs nitrogen available in / from organic matter in the soil and Fertilizer Preparation Technology can graph nitrogen to be released from fertilize

Using the Estimated Nitrogen Release graph from Analync® (Left), the Fertilizer Preparation Technology graph from TNT® (Right) allows a Sports Field Manager or an NGAG Independent Advisor to decide exactly what Nitrogen product to be applied when and in what amount*

* Always keep within each State's Nitrogen fertilizer guidelines / laws for N amount and N application windows

Soil Macro & Micro Nutrient Applications

There are at least 16 different nutrients that are essential to grass plant growth.

Air and Water supply: C, O, H

Then most soil tests address soil nutrients:

- Macro: N, P, K

- Secondary: Ca, Mg, Su

- Micro: B, Cl, Cu, Fe, Mg, Mo, Mn, S, Zn

Soil Nutrient Testing quantifies the plant essential nutrients and compares their quantity. Using that data, a soil fertility program can be built in order to add the needed plant essential nutrients and to build better balance of the nutrients in the soil.

The trust and utilization of Soil Nutrient Testing seems to be growing. To focus on supplementing needed soil nutrients is not a new concept though. This graphic above illustrates Liebig's Law Of The Minimum: "Plant growth is constrained by the essential nutrient that is most limited." Liebig's Law was established by Agronomist Carl Sprengel in 1840. Justus Von Liebig then popularized the "Law of the Minimum" in his books in 1840 and again in 1842. No, not 1942. 1842. Nearly 180 years of work reinforce using Soil Nutrient Test data to dictate what plant essential nutrients are applied during Spring and early Summer. ​



Water Management focuses specially on the Grass Water Need - the amount of water required for the grass plants to grow. That water comes from rainfall and / or irrigation.

Grass Water Need stays relatively consistent throughout the grass plant's growing season. Conversely, the amount of water required from irrigation or rainfall to provide the Grass Water Need changes dramatically as evaporation and evapotranspiration change dramatically through the seasons. In particular from Spring into Summer, June 20 (1st Day of Summer) being the longest day of the year with the sun at its highest intensity. Evaporation / Evapotranspiration will shoot up to near peak levels by late June. Average evapotranspiration can be over 4.77" in Atlantic City, NJ in the month of July, according to the Northeast Regional Climate Center at Cornell University. That is the highest potential Evapotranspiration amount on the East coast, from Washington, DC north to Maine, requiring water to sustain Grass Water Need from rain or supplemental irrigation of up to 1.2" per week

Spring Maintenance practices of Mowing, Seeding/ Sprigging/ Sodding w Superior Varieties, Soil Aeration to remove compaction, and Plant Feeding all can and will ensure that the amount of supplemental irrigation water is the least it can possibly be.

Pogo Turf Pro & Deltec FieldTester (AAA)

To best track Soil Water Content in order to correctly provide the proper Grass Water Need, a Soil Moisture Probe is used. Shown to the left in use by NGAG is POGO from Stevens Water Management (green "stick" on the left). Using POGO, or somewhat similar soil moisture testing devices such as the Spectrum FieldScout TDR, gives a numeric measure of the Soil Water Content. Using that measure in combination with the current and upcoming day's forecast, the Sports Field Manager determines when and how much supplemental water will be required from irrigation to give the required amount of water to the grass. Utilization of Soil Moisture Probes have eliminated the "guessing" previously required by Sports Field Managers working off of intuition. Eliminating that "guessing" has been able to lower water use for many sports facilities by over 25%, even in a dry year*

* Data from NGAG Field Performance Testing and POGO Turf Pro



The Spring Maintenance period for Natural Grass Fields will extend through until mid-May. By that time, a few different things come into consideration in a maintenance program:

Kentucky Bluegrass / Perennial Ryegrass By Mid-May (Outside of extreme north locations)

Maintenance Period Keys:

1. Seed and / or sod planted in March and April will start to full establish

2. "Aggressive" growth for recovery and new grass establishment will begin to be slow down, as detailed by a Spring Plant Feeding program.

3. Focus turns to "pre-stress conditioning" for the cool-season grasses to survive the UV degradation and respiration stress that overcomes cool-season plants in summer

Maintenance Period Reductions Due To Reduce / No Field Use

1. Aeration / Soil De-compaction: Need greatly reduced due to limited / no foot traffic on fields

- Surface Aeration will be required at some point before peak in summer heat, but can be delayed as long as possible (can / should base aeration decision on Soil Compaction Data)

2. Mowing Height / Grass Growth: Mowing height will start to slowly increase by the 1/4" as summer stress period begins by Mid-May. In combination with incremental height increases, as long as no play is being hosted requiring grass recovery, Growth Regulator products can be used to slow grass growth / greatly reduce mowing. Products such as Primo, Cutless, or Anuew (new product) work very well to allow grass plants to push roots and prepare for summer stress. Growth Regulators works well in combination w things like Potassium Silicate (reinforce grass cell walls in preparation for stress / invaders), anti-oxidant packages (to reduce injury from summer summer stress), and both external and / or internal UV protectants). For specifics, please contact us at NGAG.

3. Water Management: Because of no play to compact soil, and deeper / stronger roots on the Blue and Rye plants, the amount of supplemental irrigation water will be reduced. Using a Soil Moisture Probe, Sports Field Managers will be able to keep Soil Moisture Content lower than if fields were being put under stress by plant and compaction was accumulating

Bermudagrass By Mid-May (Outside of extreme north locations)

Maintenance Period Keys:

1. Sprigs and / or sod planted in March and April will start to full establish

2. "Aggressive" growth for recovery and new grass establishment will begin to be slow down, as detailed by a Spring Plant Feeding program.

3. Focus turns to driving roots and increasing density / strength without producing excessive growth and / or thatch accumulation

Maintenance Period Reductions Due To Reduce / No Field Use

1. Aeration / Soil De-compaction: Need greatly reduced due to limited / no foot traffic on fields

- Surface Aeration will be required at some point before peak in summer heat, but can be delayed as long as possible (can / should base aeration decision on Soil Compaction Data)

2. Mowing Height / Grass Growth: Mowing height should remain as low as possible for as long as possible during the summer period. As Summer approaches, Bermuda's natural aggressive growth habit takes over - allowing for a reduction / elimination of supplemental nitrogen fertilizer. Growth Regulator products such as Primo, Cutless, and / or Anuew should be utilized to slow Bermuda growth and potentially reduce mowing. If no use is upcoming / no recovery is required, high rates of certain Growth Regulator can fully "shut down" Bermuda top growth without causing harm.

3. Water Management: With no play, Bermuda can be pushed an extended period of time without supplemental irrigation water. Though allow the grass to be too dry will not allow it to grow roots and density as desired. However, the low Grass Water Need will be evident while the soil has less compaction and there is no plant stress from play.



"Required" Spring Maintenance of Natural Grass Fields is different than "Required" Summer Maintenance. To respect Government Mandates for reduced operation and to reduce the demands on a Field Maintenance Team, a good look at non-field maintenance activities should be taken to find needed reductions of work to meet Government requests and / or budget.

But the importance of Required Spring Maintenance should not be lost, or the fields / facility / and field users will be negatively impacted along with future budgets.

Though at the same time, importance to reduce exposure to the members of a field maintenance team is PARAMOUNT. If any Spring Maintenance activity puts employees in violation of CDC or OSHA guidelines - you MUST refrain from that activity and / or figure out a "new" way to carry out that activity (new meaning - in a way that keeps social distancing and meets employee protection guidelines).

This crisis WILL end. Players WILL be back on the field. And the summer / fall / early winter seasons will have more trainings and matches then ever experienced on Natural Grass Fields. The "Required" / Minimum work that is performed NOW will provide players with a safe, strong, durable natural grass surface - not only THEN, but for years to come! #StaySafe #BePatient #BeKind #BeFocused #DefeatCOVID19 #GrassCanTakeMore®


"Essential Business And Natural Grass Field Maintenance w COVID-19"

"The Long-Term Effect of Open-Spoon Aerification On Plant and Soil Properties" (By Dr. Chase Straw et all)

(Or Contact for a free copy direct from Dr. Straw)

Analync® Soil Testing from Floratine Products Group

Turf Nutrition Tool from Andersons Plant Nutrients

Evapotranspiration from Northeast Regional Climate Center:

POGO Turf Pro

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