When it comes to hybrids, the strength of the turf during the season and the durability of the system over time is often the first concern of investors. This, in fact, has always been an object of study and continuous improvement since 2011. In 2014 we found the right backing to protect the roots, in 2016 a unique method of welding the fibres to the backing to be able to renew the system several times and finally, in 2019 the HEALgreen maintenance method to enhance photosynthesis and mitigate biotic and environmental stresses. In addition, from 2019 we will be using ultra-resilient and resistant fibres to promote the resilience of the system and meet the expectations of a very long life span. Our customers are now convinced that we perform "miracles" but it is simply because our skills and experience have become unique in the industry.
Goalkeeper Nobile during an action with Samb
Many people invest in an artificial turf pitch because it is possible to train 24 hours a day, 7 days a week. In reality, the requirements for a pitch rarely exceed 1000 hours of play per year for a squad of 25 players. This is because, during the day, most children are at school and adults at work; in fact, in most cases, pitches are used after 4pm and until 8pm. One day a week, the employees close the facility for weekly rest and, between public holidays and holidays, play is played about 40 weeks a year.
The demand that POWERgrass intends to fulfil is for up to 1,300 hours of playing time on natural grass, which meets the real needs of 90% of football clubs. Natural grass can withstand a high number of playing hours during the growing season, because the turf renews itself as it grows, but the same does not apply in winter. During the vegetation period, POWERgrass natural grass can withstand up to 7 hours of play per day without suffering any particular damage, but it is advisable to reduce activity during the winter period, when the natural grass is in dormancy, if you want to maintain a high density of turf in winter. In any case, unlike other hybrid systems, the fibres are present in large quantities, all protruding over the surface, which can ensure a playable surface even if the natural grass loses its aerial part, because the fibres and roots anchored to the substrate keep the surface stable.
Please note: POWERgrass mitigates thermal shock and protects the roots due to its support and increased biological activity, but playing on frozen ground must be avoided in order not to cause major damage to the lawn and to preserve the health of the players.
Experience from more than 30 installations confirms that POWERgrass does not raise natural grass sods, as is the case with other reinforced systems, due to the strong anchoring of the roots to the innovative backing and the presence of a large number of fibres on the surface. When the game is intensive and the grass does not grow to recover, the playing surface remains flat and it is possible to play on the artificial fibres present on the surface in large quantities while the roots provide stability, traction and cushioning, until the next vegetative growth in spring. By following the teachings of POWERgrass technicians, through easy but constant maintenance, it is possible to achieve a high quality of natural grass during the growing season without the risk of stopping a game in winter as long as the pitch is kept clean on a weekly basis.
A recurring question from football pitch operators is: "Can a POWERgrass pitch be the best solution for our case?"
Although everyone agrees that playing on a hybrid pitch brings greater benefits and playing safety than on a natural or synthetic pitch, and although the cost/benefits also show that the economic, environmental and hydrogeological benefits are favourable throughout the life cycle of the system, the doubt that natural grass can be ruined tends to scare inexperienced operators. To this end, in order to understand whether the hybrid field is the right choice, it is good to refer to 1) the weekly utilisation index, 2) the annual fruition index and 3) the total duration index to guide the choice, based on actual utilisation data.
1) Weekly utilisation index - WUI (Weekly Usage Index)
Although POWERgrass, in its 'Heavy Duty' version, has a high number of very strong fibres that allow you to play without the aerial part of the grass, the goal of a hybrid pitch is to play on natural grass, so you need to check the weekly utilisation index (WUI) of your pitch.
The WUI calculates the maximum weekly playing load exerted by players on a given surface and is calculated using the following formula:
WUI = Uw x Pm ÷ A
For example, an 11-a-side pitch with a playing area of 100x60 metres is used for about 30 hours a week by about 22 players. In this case, the WUI would be 30x22÷6000 = 0.11. The following table shows a calculation for some pitch types.
|1) Weekly Usage Index - WUI|
|WUI peak calculation in Regent's Park, London|
The goal of the index is to objectively make it possible to preserve good natural grass coverage for at least 75 per cent of the playing surface during the sports season, while accepting a significant reduction during the winter months.
In general, a hybrid POWERgrass pitch is recommended as long as the WUI reaches a peak of 0.18, as recorded at Regent's Park, London, although there are reports from Grosseto of higher usage.
2) Annual fruition index - AFI (Annual Fruition Index)
This index calculates the total annual hours in which the pitch is used for games or training by the number of players on the pitch using the following formula:
AFI = Uw x Pm x Wy
In order to estimate the annual fruition index, also taking into account the climatic variations during the season, a good rule of thumb is to set a limit of 40 hours of play per week during the growing period from mid-March to mid-June and from September to November, while in the winter months (December, January and February and up to mid-March) reduce this to 20 hours per week if possible (26 weeks at 40 hours + 13 weeks 20 hours = 1300 hours per year) then multiply the hours in which the pitch is usable by the number of players present on it. In our example, by calculating 22 players present on the pitch, we can estimate an annual fruition index of 28,600 hours of attendance (1300 hours per year for 22 players), which meets the requirements of a high-frequency artificial turf pitch. The following table shows a calculation for an 11-a-side football pitch during a competitive season.
|2) Annual Fruition Index - AFI|
|Spring - Autumn||40||22||26||22 880|
|Average playing week||33||39|
|Average in 52 weeks||25||52|
|Annual Fruition Index - AFI||28 600|
|Calculation of AFI in Regent's Park, London|
This index provides an estimate of the annual hours of pitch attendance and can also be an average cost basis for subscriptions with individual players.
The annual attendance index can be measured through the installation of an attendance meter and managed through a special application. Furthermore, the average age of the athletes should be highlighted in order to collect useful data in relation to the average weight of the athletes.
3) Lifespan Warranty Index (the number of annual fruition times the number of guaranteed years)
The lifespan warranty index is derived by multiplying the annual usability index by the number of years of warranty granted and a proof that the system manufacturer places in the product subject to certain conditions of use and maintenance, and is calculated using the following formula:
LWI = AFI x Yw
AFI = Annual Fruition Index
Yw = years of system warranty
For example, if the system warranty is for 5 years for 20,000 hours of attendance, this means that the guarantee operates for one of the values reached before, i.e. it is for 5 years or 100,000 hours of attendance with a maximum limit of 20,000 hours of attendance per year.
|3) Lifespan Warranty Index - LWI|
|POWERgrass||20 000||5||100 000|
The system's lifespan warranty index is an index that investors take into account in the pitch's amortisation plan because its useful life, i.e. its total usability, depends on it, a bit like the total mileage of a car or the total hours of use of a vehicle.
During the growing season, the natural POWERgrass lawn can withstand up to 6 hours of play per day, without suffering any particular damage, but it is advisable to reduce activity during the winter period, when the natural grass is in dormancy because it can gradually thin out, although the fibres, present in high quantities, can guarantee a playable surface. POWERgrass mitigates temperature changes and protects the roots, thanks to its backing and increased biological activity, but playing on frozen ground should be avoided in order not to cause major damage to the lawn and to preserve the health of the players.
If the weather is extreme, it is advisable to integrate a heating system in the root zone or cover the pitch with a non-woven geotextile during frosty nights and until late morning the next day, if the temperature is expected to be below -5°C for several hours during the night. If the frost persists even during the day, it is best to maintain the cover and suspend sporting activities.
In the case of playing and training fields for professionals, it should be borne in mind that athletic preparation begins a month earlier than for amateurs. In Italy, in August and until mid-September there are high day and night temperatures for the growth of cool season grasses (Lolium Perenne, Poa Pratensis and Festuca Arundinacea) and the double stress of heat and intensive play can cause damage to the turf; therefore, it is better to use the field early in the morning to avoid excessive stress to the turf. If intensive use is necessary with temperatures above 25°C, it is advisable to seed warm season grasses such as Bermudagrass (Cynodon Dactylon) or Paspalum Vaginatum if you are in the presence of saline water.
It may seem trivial, but it is worth repeating that grass is resistant and recovers quickly in the POWERgrass hybrid system, as long as the play is distributed over the whole field. Therefore, all static training is prohibited and you must move around the pitch every day, changing the training area. For example, "skips" from a standstill are extremely intensive for the natural grass, which can give way after a few hours. Concentrated training should be placed in different areas of the pitch each day, such as goalkeeper training, short passes of the ball etc.
The pitch supervisor should collect each item at the end of training and move the target pins to different areas of the pitch the next day to distribute the weekly playing load over the whole pitch surface. Where it is not possible to have a dedicated area for goalkeeper training, mobile goals, to be moved daily, should be used to preserve the fixed goal area, which should only be used for matches.
Balanced nutrition, combined with frequent raking for surface cleaning, light perforation up to the backing to alleviate soil compaction and periodic localised reseeding of the most damaged areas, mitigate and compensate for the stresses of intensive play. Cultivation according to the green maintenance method, together with careful water management for irrigation, keeps soil conditions in the favourable range for roots and mitigates thermal stress. In this way, the need for specialist maintenance during the summer break can be reduced and overall maintenance costs and water consumption can be kept down.
Correct use of the field and constant maintenance promotes a rich and homogeneous lawn cover, almost all year round. In this way, the natural grass covers and protects the synthetic turf, which is not exposed to the sun as much and does not age the synthetic fibres by UV rays, especially in summer when the sun is stronger and warmer.
The life span of POWERgrass is therefore estimated at least 20 years of intensive use, with some precautions on maintenance work to avoid irreversible damage to the backing and synthetic fibres.
As an indication, but not an exhaustive list, some prohibited operations, operations to be carried out by POWERgrass technicians and alternative cultivation solutions are indicated.
Aggressive scarifying with fixed or moving blades must be avoided. In addition, repeated top-dressing must be avoided as it buries the synthetic fibres and consequently, the crowns of the natural grass seedlings are not protected. As a rule, top-dressing on natural turfgrass lawns serves to level the surface and close the small holes that players make in the playing surface. This does not happen in POWERgrass, because we have never seen the need for top-dressing.
Do not use disc seeders which can cut fibres, but those with conical nails which tend to move the fibres along with the lawn. For obvious reasons, coring with hollow tines and deep cuts with spikers is not permitted to avoid excessive damage to the artificial backing. Grass roots tend to re-sod the cut, but there is a risk of lifting the sod along with the artificial grass during the operation.
For the returfing operation, i.e. the removal of the natural grass together with the soil deposited on the surface and the reseeding from scratch every 3-4 years, consult only POWERgrass' authorised technicians, otherwise the system's 12-year warranty will expire.
A very beneficial operation that POWERgrass strongly recommends is frequent passage with the roller with nails penetrating the first 30-35 mm of the surface to alleviate compaction above the backing. In addition, mechanical raking keeps the surface clean by removing the dirt that players generate from intensive play.
It is also possible to periodically use the Verti-Drain with the 8 or 12 mm thin nails to break up the soil deeply and make it more draining and softer. This operation is particularly suitable when the weather is excessively wet.
Use cylinder mowing machines to cut the grass and generally follow the HEALgreen maintenance programme, consulting POWERgrass technicians on a regular basis.
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POWERgrass hybrid turf field
Synthetic turf field