Hybrid grass or reinforced natural grass is a product created by combining natural grass with synthetic reinforcing fibers. It is used for stadium pitches and training pitches, used for association football, rugby, American football, golf, and baseball. Reinforced natural grass can also be used for events and concerts. The synthetic fibers incorporated into the root zone make the grass stronger and more resistant to damage.
The first generation of hybrid grass appeared in the 1990s. Grass roots were allowed to intertwine with a mix of sand and synthetic fibers as they grew. Three main methods exist to insert synthetic fibers in the root zone. The first is to inject fibers into the sand with a tufting machine. This is the method used to create GrassMaster.
The second method is to mix fibers and sand in an automated plant and install it afterward on the pitch: this process is known as Fibresand.
The third method is to put a mat with woven or tufted fibers on the surface, brush in sand or sand mixes afterward to keep the fibers in an upright position, and seed grass mixtures finally. The natural grass roots through the mat and stabilizes the system.
Some of the older hybrid grass pitches were harder than unreinforced natural grass. This created concerns about the risk of injuries for players and maintenance for groundskeepers. Because of this, the sub-base composition for hybrid systems evolved over time. It now often combines the following elements: sand, which is the main component of the rootzone; synthetic fibers, to reinforce the pitch; and an additional element to enable softness.
There are multiple patented technologies that concern hybrid grass, such as the following examples: XtraGrass developed by Greenfields b.v., and SISGrass, developed by SIS Pitches. The latter uses specific technology to inject polyethylene fibers into the soil, AirFibr, a technology developed by Natural Grass, which uses natural cork as the softness element, and Fibrelastic, developed by Mansfield Sand, which uses elastane fibers as the softness element. and GrassMaster, developed by Desso, obtained a patent on a hybrid grass system based on injected fibers.