Straw Wattles & Terra Tubes
Hydroseeding is a planting process used by professional turfment to prevent natural erosion and improve soil and sediment control. In this process seed, fertilizer, and fiber mulch are mixed with water in proper proportions inside a tank, and then sprayed over a prepared ground or soil. The slurry of seed and mulch is transported with trucks, aircrafts or helicopters and then sprayed over the designated areas through high pressure hoses.
Hydroseeding is a very effective method that grants much higher percentages of seed germination (often higher than 95%) and better grass plant survival, as well as greatly reducing soil evaporation by acting as a soil stabilizer that prevents water and wind erosion, and it’s often used in combination with other devices such as straw wattles and terra tubes.
To further reduce soil erosion, straw wattles are installed prior to hydroseeding in order to slow down surface sediment movement. Straw wattles (also called straw worms, bio-logs or straw noodles) are often used instead of silt fence or straw bale dikes as they are a great instrument for erosion control. They help in stabilizing slopes by shortening their length, and are also employed as they can filter soil water as well slow and spread its flow, preventing gully and rill development and natural sheet erosion.
Straw wattle installation consists of tubes of punched or blown rice straw secured in place bybiodegradable wood stakes restrained by a rope, or by digging furrows, and usually last for three or four growing seasons. Straw wattles vary in length and size. Straw wattles also helpseed seeding in difficult areas like slopes, as they help keeping the slurry fertilized solution in place by preventing excessive soil drainage.
This way the mulch will blend much more uniformly inside the soil, allowing grass plants to grow sturdier and faster and preventing sediment from dragging seeds away from planted soil.
Similar to straw wattles, terra tubesare heavy duty cylindrical tubes that encase wood and other fibers, including several engineered polymers, used for sediment retention. A more technologically advanced solution, terra tubes are a very effective device to trap, filter and treat sediment runoffs, preventing and treating storm water damage. Stormwater runoff can in fact carry sediment and seeds off slopes, preventing germination and polluting nearby lakes, streams, ponds and river with overland runoff.
Terra tubes and straw wattles capture and filter this sediment greatly reducing hydraulic energy, holding seeds in place so they can settle and grow. Terra tubes are more expensive yet much more efficient than straw worms and fiber rolls, as they possess internal air space and cavities that ensure a continuous flow that prevents sediment from washing over on top of the filtration system.
Also the engineered fibers possess a much greater surface area than common organic fibers, resulting ingreater filtration thanks also to the inclusion of specific substances that produce coagulationand aggregation of sediment particles within the tube.
Both straw wattles and terra tubes are also used for different purpose, such as protecting storm drains and sidewalks from sediment pollution as dirty water washes into gutters, or to contain spoil piles from spilling on flat ground. Terra tubes are often employed together with other erosion control technologies such as Erosion Control Blankets (ECBs) and Turf Reinforcement Mats (TRMs) to further improve their efficiency.