Hydroseeding... Keeping Soil Where It Belongs
|By Phillip Meeks|
There was a time when soil erosion was, by and large, a farmer?s concern. As machinery was developed that allowed the tillage of greater acreages, the result was horrifying losses of topsoil to the effects of wind, water and gravity.
The Dust Bowl of the 1930s illustrated erosion taken to its utmost. Drought and exposed soil factored into a nightmare of massive dust storms in the Plains States, but one positive that came from it all was a new erosion consciousness.
The advent of the Soil Erosion Service ? later to become the Soil Conservation Service and, ultimately, the Natural Resources Conservation Service ? begat program upon program to educate agricultural producers on methods to keep the soil in place. Contouring, terracing and other soil-conserving practices became common as a result of these efforts.
Today, erosion isn?t just an agricultural worry. As suburbia expands to take in the surrounding hillsides, home and business owners, too, must face this adversary. Locations in need of landscaping are usually prone to erosion and sedimentation, and careless landscape practices can even contribute. Or, as David Franklin, vice president of Metamorphosis Erosion Control in Napa, California, puts it, ?Landscaping is erosion control.? Once valuable topsoil is lost, after all, it will prove difficult if not impossible for a quality landscape to become established. Therefore, protecting that soil resource should be at the top of a landscape contractor?s list of concerns.
Another influence on urban erosion control is the Phase II Final Rule of the EPA?s National Pollution Discharge Elimination System (NPDES), which regulates storm water discharge from small construction projects (one to five acres).
?New legislation tied to Phase II,? says Wally Butman, executive vice president of Finn Corporation, ?requires an erosion control plan for sediment control on one-acre or larger sites. Therefore, more small to mid-sized hydroseeding contractors will be called on, and the opportunity will open up for them to do more of this type of work, as opposed to strictly residential and commercial lawns.?
Soil Science 101
Occasionally, it?s good for even the most seasoned experts to revisit the basics, and what gets more basic to the landscaping profession than the soil beneath it all?
A typical ?soil profile? has distinct layers that include the O, A, B and C horizons, which can vary widely in their relative thickness. The O horizon is at the surface, and consists of organic matter. When leaves fall, or when trees are mulched, this becomes the O horizon. These organic elements are the source of nutrients that plants require.
The A horizon is just beneath the O, and is made up of both organic and mineral materials. It is within the A horizon that most plant roots will be found, and it?s this horizon that?s considered topsoil.
Once in the B horizon, organic matter begins to get more scarce as mineral matter increases, and in the C horizon, no organic substance is found. Instead, the C horizon very closely resembles the parent material (i.e., rock) from which it came.
From a horticultural perspective, the O and A horizons will have the biggest impact on plant health, and these are the layers that will bear the harshest erosional scars. When heavy equipment compacts the topsoil ? such as during construction activities ? soil pores close and soil infiltration rates decrease. To illustrate, think about two cylinders (such as coffee cans open on both ends) placed on a) an undisturbed site and b) a site compacted by machinery. If you pour equal amounts of water into each cylinder, the liquid will infiltrate into the undisturbed soil relatively quickly. On the other hand, water will linger above the surface of the compacted soil. If the latter is on the slightest of slopes, rain or irrigation water will move along the surface before soaking into the ground, carrying soil particles with it.
Contractors can correct compaction in different ways: by mechanically loosening the soil; by adding amendments such as compost to improve the soil?s porosity; by applying synthetic erosion control materials like jute mesh; and by adding plant materials, which will both anchor the topsoil and improve porosity.
Hydroseeding: a cost-effective solution
Sod is a fast way to get vegetation on a bare landscape, but for some clients, this method is just too costly. Broadcast seeding is an option as well, but it?s quite labor intensive. Hydro-seeding, by comparison, is a more affordable alternative.
?The primary reason most of our customers choose hydroseeding is for the cost savings,? explains Kerry Thomas of Grass-Kat Lawns in Waco, Texas. ?A
lot of the commercial sites we seed are large in size, and the design engineer is looking for ways to reduce project cost. The same thinking applies to homeowners.?
Thomas believes that sod as a cure-all approach is ?old-school thinking? and estimates that hydroseeding can cost as little as half the cost of sod, depending upon job requirements and specifications. In other words, the contractor who has hydroseeding capabilities at his or her fingertips will be able to reach a greater number of customers than those who deal exclusively with sod.
Finding your clients . . . and serving them
Says Franklin, ?Construction sites have been identified as one of the more significant sources of water pollution, because of sediment running offsite. The window of time between clearing a site and stabilizing it with landscaping is when erosion is likely to take place. Therefore, clearing only those areas that will be promptly completed is an important strategy.?
Franklin makes the point that wise landscape designers will consider the use of cisterns or other detention methods to recharge water displaced by hardscapes or soil compaction. If X amount of rain falls onto an undeveloped site, X amount will continue to fall after a home, a garage and a sidewalk have been installed. One must somehow compensate for this reduction in soil area, or else pay the consequences.
From Butman?s perspective, the EPA rules will open new doors for small to mid-sized contractors.
?For a contractor who?s used to doing anywhere from 15 to 20 acres of residential work,? says Butman, ?I foresee that doubling and tripling if he ties into the erosion control opportunity.?
Projects beyond new developments and new construction are out there as well, waiting for the equipped contractor to come aboard. These may not be the bread and butter, but they can often prove to be profitable undertakings.
?The majority of our job sites are new construction,? Thomas explains, ?where soil preparation is typically done by the general contractor with the final grade. Occasionally, however, we have to go in and remove existing vegetation and prepare the soil.?
Beretta explains that her company?s clientele also come from across the spectrum. ?Most of our customers are homeowners who have done a majority of their own landscaping,? she says, ?and they need us for the final installation ? the lawn. We also have contracts with local home builders in our area, many of whom install at least a front yard for the new homes they build. And we do business with local utility and excavating companies, hydroseeding over trench lines and septic systems.?
The bottom line is that soil disturbance of any kind opens a door for hydroseeding.
Be prepared to stand in the role of educator if you want to build demand in your part of the country.
According to Beretta, many fail to appreciate what hydroseeding can mean to them.
?Most people still think of it as the green stuff you see along the highways,? she says. ?Very few know that we can customize seed mixes for the specific site; we can spray erosion control mixes and wildflower mixes. As the public becomes more aware of the applications for hydro-seeding, it will only increase business for those contractors who offer hydroseeding and do it right.?
Furthermore, she underscores the need for contractors to have a firm understanding of accepted techniques before hitting the road with these services.
?I believe hydroseeding can be very profitable,? she says, ?if the landscape contractor makes sure he uses the right amount of materials for the specific job ? the proper amount of mulch and tackifier, the right type of seed mix, all applied at the right time of year on soil that has been properly prepared. You make money at hydroseeding by doing it right the first time and eliminating costly call-backs and re-sprays.?
Erosion is one of the most detrimental forces to soil health and, therefore, to plant success and, ultimately, to the green industry. Erosion control is a tremendous opportunity for contractors to step up to the plate and play a role in improving clients? property values and environmental quality. While suburban America may never host a Dust Bowl, erosion can be as serious to a homeowner as it is to a farmer.