Reinforce natural grass is not so simple ... first of all you have to respect the rules of nature.
Hybrid systems are not new. The first system was developed in the United States in 1993. It seemed a brilliant idea, but had a limited success for the following reasons:
- difficulties in producing a functional fabric to achieve the targets
unfavorable growth conditions of natural grass:
- it was particularly difficult to fix the artificial fibers to the support (backing). Roots provide support to the turfgrass, they absorb water and nutrients in the soil. To perform their function both roots and bacteria useful to mineralize the nutrients need oxygen to breathe. Having to breathe the roots and stimulate their development even under the backing, is not possible to use the classic fabric (closed) in PP coated with latex or PU, which is necessary to fix the fibers to the support. The industry has applied an open tissue (geonet) and tried to lock up the fibers by applying a second support biodegradable, which over time would decompose to permit the roots to penetrate the fabric (geonet) and grow also below the backing, in the background growth medium. Experience showed up that degradation does not occur on time compatible with the needs of the grass, because it depends on many factors: physical and environmental.
- The lock up of the fibers is weak and with time the degradation of the second support loosens completely the fastening of the fibers to the backing. Natural grass simply remains anchored to the geonet, but the artificial fibers do not contribute to the playing surface stability. When the natural grass is weak, or so worn, gives away and together with the grass sods are removed even the artificial fibers, uncovering the backing, therefore reconstruction is necessary.
Few, even today, promote a fabric with an open backing (geonet) without using the second support to fix the fibers to the geonet. The artificial grass produced in this way is incomplete, not suitable, as it is not possible even to infill the filling material and brush up the fibers that should tick at least 1-2 cm above the growth medium. Often, we observe that fibers are buried in the growth medium and do not perform any reinforcement or protection on the grass crown and the stability of the growth medium. In this case the only reinforcement is the fact that the roots can be anchored on the geonet.
playing surface very hard:
- during the first period of growth, the roots do not penetrate the fabric until it degrades, meanwhile they grow above the backing increasing the thatch layer. A shallow growth medium needs frequent irrigation, consequently the roots remain "comfortable" in the surface above the backing. It's known that turfgrass in these conditions is not resistant to any environmental stress or intensive use,
- in some cases the excess of moisture associated with a rich biological activity consumes oxygen (O2) in the soil, giving rise to an anaerobic activity that consumes the little oxygen left from the water (H2O) and oxides of sulfur (SO2 and SO3) thereby releasing hydrogen (H) and elemental sulfur (S). Those two elements form a very powerful acid, a toxic poison, hydrogen sulphide (H2S) with a characteristic smell of rotten eggs. The persistence of these conditions results in a fatal poisoning of the grass that becomes red, rootless and dies.
- some producers fix the fibers smearing liquid adhesive over the entire surface or in large part of the support with one of the classic methods for the artificial turf (latex, polyurethane, thermoplastic), then make a high number of holes to encourage the penetration of the roots. In truth, the roots do not pass, probably due to the fact that the number of holes is limited and because, in said backing, the space between the holes, is impermeable, so the water deposited above the backing forms a invisible water barrier, due to the surface tension of water blocking gas exchange, that reflects on non favorable growing conditions for the roots under the backing. Another plausible explanation is the fact that the water deposited above the backing helps retain excess moisture in the rootzone above the backing, intensifying the phenomenon of intoxication with the formation of hydrogen sulphide (H2S).
- over the years the industry has always built an hybrid grass with artificial turf and sand according to the USGA indications. The sand is a very resistant to wear and does not get compacted easily, but after a certain number of hours of play even in sandy soils the surface becomes hard and requires decompaction. Introducing synthetic fibers in the sand to increase stability, after the first period, the surface becomes even harder and requires decompaction more frequently. The presence of a fabric with weft and warp open tissue (geonet), often used to distribute the loads, at the first period works well, but subsequently form a very compact surface. If nothing is done, the lawn undergoes a hardening in the surface and tends to thin out.
PowerGrass® is not simply a product, it is a concept
All details have been subject of reflection and a long study to understand the ideal characteristics of both synthetic turf and growth medium.
Using a backing for artificial turf, open and breathable over the entire surface, non-biodegradable that would allow gas exchange also under the backing from the very beginning, is an essential condition to start the development of an hybrid system and is the main claim of the patent.
Well fixed synthetic fibers to the backing are also elementary elements, but there are other features that complete the project such as:
- make sure that the backing of artificial grass is not too hard, but at the same time resistant,
- study a growth medium to optimize sports performance, growth conditions of the grass that promotes development of roots above and below the backing.
The mixture of sand with Geofill® PG ... is essential to get the best outcome from PowerGrass
Identify the best mixture suitable for the cultivation of the grass in a hybrid system, was not easy, it took over 2 years of study, testing all possible variables with any organic and inorganic material available in the market today, and the results amaze best experts in the world. Working outside the conventional, we gave space to the genius of Dott. Sarris. Get the most cost optimization is not easy, but it's his job.
The result was a special blend of sand according to USGA specifications, with an organic soil conditioner, Geofill® PG - based on coconut fibres is patented and is designed specifically for sports turf.
Geofill® PG is the result of a long reflection and intuition thanks to a deep knowledge of both worlds: that of natural grass and that of artificial turf.
Over coconut, the finest cork for the production of wine cork stoppers was a surprising discovery. Geofill PG increases the porosity and moisture content of the sandy growth medium, attributes a cushioning effect to the playing surface and reduces soil compaction.
Observe the limits of an old hybrid system: the fibers are "buried" in the sandy substrate and offer no protection to the grass crowns. Moreover, the fastening of artificial fibers to the horizontal support is inadequate, when the natural grass gives away, even artificial fibers are removed away from the player.
Only elastic fibers (on the right) maintain an upright position and protect the crowns of the plants of natural grass.
Competition no roots
A strong limit of another old hybrid system: the roots do not penetrate the backing until the partial degradation of the backing takes place. When this happens affects approximately 1/3 of the surface of the support as the remaining 2/3 is waterproofed from the coating over the backing that welds the fibers to it. A strong limitation when only 8-10 weeks are available for the development of natural grass and even after as rooting affects only 1/3 of the surface.
Old Hybrid system
The synthetic turf should not prevent the growth of natural grass: in most of the older systems, we observed that the soil becomes very hard and suffocating the growth of natural grass.
PowerGrass over winter
In PowerGrass the artificial turf assists the growth of natural grass: the artificial yarns provides shadow to grass shoots against the summer heat meanwhile the artificial support will provide water content and preserve the heat in the growth medium against the winter cold.