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(Conservation Currents,
Northern Virginia Soil and Water Conservation District, September
2005)
Let’s face it, we love our lawns. Those
green expanses are where we play ball with our kids, frolic
with the pets and host our weekend barbecue.
Unfortunately, many of the synthetic chemicals
we add to keep our lawns lush are not good for our families,
or the environment. Many chemical weed and feeds contain herbicides
that have been linked to increased rates of cancer in people
and pets. The use of chemical fertilizers and herbicides by
residential homeowners, including many of us in Fairfax County,
is one cause of deteriorating water quality in the Chesapeake
Bay.
 What
can we do to keep our lawns, our families and the Bay healthy?
The answer may be to use corn gluten! In the 1980’s Iowa
State University turf grass researcher, Dr. Nick Christians,
discovered the natural weed and feed capability of corn gluten
meal, a protein-rich by-product of corn processing. Commonly
sold as feed material for livestock and pets, corn gluten meal
contains 10 percent slow-release nitrogen by weight, making
it a natural fertilizer. In turf grass experiments with corn
gluten, however, Christians observed a startling pattern. Turf
plots where corn gluten had been applied seemed also to have
fewer weeds! Corn gluten, Christians determined, contains amino
acids that actually prevent seed germination, making it a natural
pre-emergent herbicide.
Corn gluten meal offers pre-emergent control
of such weeds as dandelions, crabgrass, pigweed, plantain, lambs
quarters and curly dock. Although it does not control perennial
weeds like red clover or bentgrass that have already invaded
your lawn, corn gluten’s nutrients do make your grass
healthier and stronger. Over time, researchers have observed
that these tough perennial weeds also become less prevalent
as they are crowded out by a happy, healthy lawn. One distributor
touts as much as 91 percent weed control after three years of
twice yearly applications of corn gluten.
Corn gluten seems like a wonder product, but using
it does have certain drawbacks. Compared to synthetic products,
corn gluten meal is more expensive and offers less weed-control.
And as with other pre-emergent herbicides, corn gluten must
be applied close to the germination time of the target weed
species, typically early spring. Despite our need to get out
there with the daffodils and fertilize,
this isn’t the best time to add nutrients to your lawn.
Corn gluten is also non-selective; during the 4-6 weeks following
application, it will prevent all seed germination. So if you
use corn gluten, wait several weeks before overseeding your
lawn. (Corn gluten can also be used for weed control around
ornamental plants and vegetables, but be sure to keep the product
out of beds in the 4-6 weeks before you sow seed.)
Despite these few drawbacks, corn gluten offers
what most of us are looking for: a simple (and safe!) approach
to lawn care. Horticulturists suggest applying 10-20 lbs. of
corn gluten (the equivalent of 1-2 lbs. N) per 1,000 sq. ft.
twice yearly, once in the spring, when daffodils and forsythia
start to bloom (to prevent summer weeds from sprouting), and
once in the fall, around Labor Day (for winter weed control
and fertilization). The product directions suggest gently watering
in the corn gluten to activate it. Still, it’s a good
idea to check the forecast before each application. In general,
applying lawn care products right before a rain won’t
protect the Chesapeake Bay or your investment! During the month
after application, water as little as possible to allow the
soil to dry out periodically.
Corn gluten meal is sold as a yellow powder and
in a granulated form appropriate for conventional spreaders.
Both product types are available at many hardware stores and
garden centers and are marketed under a variety of brand names
including Cock-a-doodle DOO Organic Weed Control (Pure Barnyard
Company, Inc.) and CONCERN Weed Prevention Plus (Woodstream
Corp.). Don’t be afraid to ask for help from your garden
center salesperson, or go armed with the list of currently licensed
companies and product names from Nick Christians’ corn
gluten web page at Iowa State (http://www.gluten.iastate.edu).
The advantage of weed and feeds including corn
gluten meal is convenience. One product, one method of application,
one trip to the garden center! Yahoo! However, when you apply
corn gluten meal or any other weed and feed product, particularly
in the spring, make sure not to over-fertilize your lawn. Cool-season
grasses produce most of their roots from September to
November making this the best time to fertilize. In
contrast, spring fertilization stimulates blade growth (read
more mowing!), but can weaken roots leaving your lawn susceptible
to fungus and other disease-causing agents. Often too, in spring
the grass just can’t use all the nutrients you’ve
added and they wash away into our streams, ponds and Bay.
For the healthiest lawn (and Bay), have your soil
tested every three years by the Virginia Tech Soil Testing Laboratory
to determine your lawn’s fertilization and lime requirements.
Soil sample boxes and forms are available at all Fairfax County
public libraries or at the local Virginia
Cooperative Extension office. To reach the Cooperative Extension
by phone, call 703-324-5369, TTY 711.
And if your lawn is in good shape, consider skipping your spring
lawn rituals. It could help the Bay, and will definitely save
you time and money.
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