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Deciding Whether to Drill,
Broadcast, Sod
or
Hydroseed
There's a Right Time for Each
The two-acres are flat as last night's
champagne and the stable soil could support Army tank practice. Hydroseed,
drill, broadcast or lay sod? Installation cost of such a project is often the
sole point given consideration—and much of the time the cost of
maintenance, crucial to protecting the original investment, is overlooked. Final
costs must be validated by a successful installation. Rework can spiral costs out of control.
In a commercial application, such as sports turf, the effect of an installation
that doesn't "take" could delay use, leading to lost revenue.
If we assume the plot is not critical
for income and that establishment time is flexible, we could probably get by
quite cheaply using drilling or broadcasting methods. The stable condition of
the subsoil allows wheeled vehicles free roam without harmful effect. We're
offered one of those simple answers—a "gimmie". The likelihood of
finding an abundance of such easy answers is poor. More commonly we are faced
with an irregular, broken or sloped area that might need berms and swales to
combat poor drainage. There may be an even poorer irrigation system. Time and
money are tight. The answer becomes more elusive and the stakes are higher.
Predicted winter rains are supposed to be the worst in 15 years and threaten
massive erosion. What now?
Making a Choice
Drilling or broadcasting are unlikely
to be the best choice this time when quick establishment is needed to prevent
erosion. Uneven ground may prevent efficient use of seeding equipment. In the
case of engineered slopes, the equipment may cause damage to soft or unsettled
soils. It is clear that drilling or broadcasting would be a poor choice in
this case, leaving hydroseeding or sodding to consider.
Timing
A darkened sky and the first few rain
drops suggest quick action. Careful planning would be better but the landscape
contractor, coming in at the tail end of a project, may have had little
influence over planning. His services may almost be an
afterthought and are certainly less pressing than completion of a building,
arena or stadium. Sod may be the only choice to get down erosion protection
quickly. But the high cost of the sod blankets—ten times or more than the
cost of hydroseeding—and the labor-intensive installation could be a
limiting factor. Hydroseeding offers some distinct benefits that span the
differences between the cheap, easy, slow-establishing drilling or broadcasting
methods and the quick, but expensive, pregrown sod.
- Powerful pumping equipment means that in most cases hydroseeding can be accomplished from the sidelines, important in those cases where new slopes or loose soils will not support equipment
- The slurry, by its very nature, protects the soil from wind and rain erosion under most conditions and a damaged crust may be easily repaired. In cases where the crust is cracked and has not been removed, it will self-repair with the next moisture it receives.
- A uniform application can be assured visually. The seed is suspended in the colored slurry then sprayed on the soil. An even appearance is the sign of even seed distribution. This is a real advantage with seeds—such as Gazania or needle grass—that are hard to spread evenly using other methods
- Quicker establishment is possible. Hydraulic application of pre-germinated seeds—even to the point of maturity when the seed leaf and seedling root radical are apparent—can buy several day's head start. Using pre-germinated seeds in other mechanical installation methods is risky since loss of moisture for even a short time will kill the young plant
- Poor irrigation coverage is quickly revealed in a hydroseeded plot, pointing to the broken or poorly-adjusted sprinkler with retarded or poor growth. Sod will camouflage poor irrigation until it is too late to rescue the dead-or-dying strips and they must be replaced at, perhaps, significant cost. The hydroseeded area can be resprayed immediately to avoid the loss of days or weeks in establishment.
- Hydroseeding—like spray-painting—covers irregular surfaces as no other method can. Slurry containing a tackifier glues the seed to the soil and the resulting crust foils birds attempting to steal your new ground cover or turf.
- Additives may be mixed into the slurry and applied simultaneously with the seed. Fertilizer and soil amendments such as mycorrhizal inoculants are applied with the seed in a single step. This is an excellent way to avoid disturbing the soil and turning up dormant weed seeds.
Understanding the full effect of turf
and ground cover installation methods will allow you to select the best method
to meet your client's goal. You can tap the knowledge of Albright's consultants
by e-mail.
See Hydroseeding,
Before and After.
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