Conservation
72 www.WallacesFarmer.com
●
September 2009
How much
to trap a ton
of sediment?
By LYNN BETTS
W
ANTING to stretch
the
conservation
money he administers
from the Iowa Department of
Agriculture and Land Stewardship as far as he can, Phil
Patterson goes the extra mile.
In fact, he can tell you the cost
of trapping a ton of sediment
for every conservation practice he helps apply in the North
Thompson River Water Quality
Project in Adair County.
Patterson, an environmental
specialist for IDALS, runs sediment delivery calculations
for every application for state
cost-share funds in the project.
Now in its fifth year, the
North Thompson project has
sediment reduction in Adair,
Madison and Union counties
as its primary goal.
“In fiscal year 2009, it cost
$204,084.46 in state watershed
protection funds to trap 2,450
tons of sediment, or $83.30 a
Key Points
■ Structures a top conservation
practice to trap sediment.
■ Top terrace gives most bang
for buck in stopping erosion.
■ Federal, state incentives given
for contour buffer strips.
ton,” says Patterson. Practices
included grade stabilization
structures, terraces, water
and sediment control basins,
and grassed waterways. Other
state and federal conservation
programs were also used in the
project area, including CRP and
Iowa Buffer Incentive funds to
apply contour conservation
buffers.
Patterson has found that
structures, or watershed dams,
are at the top of the list in
trapping sediment most economically. “If you look at the
cost of trapping a ton of sediment each year for the life of a
structure, that cost is minimal
TRAPPING SEDIMENT: Phil Patterson (left), an IDALS environmental specialist, talks with farmer
Chuck Green about the sediment that Green’s 12-acre lake is keeping out of the North Thompson
River and other rivers downstream.
for the benefits the structure
provides,” Patterson says. “For
example, a dam built in 2007
to trap sediment on the Chuck
Green farm cost the watershed
$24,987. It is trapping 689 tons
of sediment a year, at a cost of
$36.27 a ton. But over the life of
the dam, it will cost only $1.04
a ton.”
While Patterson looks at the
cost of keeping sediment out
of the river, most landowners
look at other advantages to the
structures. In Chuck Green’s
case, he likes the largemouth
bass, catfish and bluegill fishing
that will come from his 12-acre
lake, as well as the wildlife it at-
tracts. He’s already seen more
ducks and geese. “I’ve thought
about building a house on the
hill above the lake, and my
grandchildren really enjoy it
when they come out here from
Colorado,” Green says.
‘Top terrace’ system
Always conscious of conservation costs, Patterson is also an
advocate of the “top terrace”
system with conservation buffers below. “Terraces do a good
job of trapping sediment, but
they can be expensive,” he
says. “You get the most terrace protection for your money
with the top terrace in a field.
Usually more water falls on
more acres on the more level
land above the top terrace,
and that terrace is the one that
slows runoff before it can build
up to start down the slope,”
Patterson says.
He adds that no-till and
contour conservation buffers
below the top terrace can do
a decent job of erosion control until more terraces can be
built.
CONTOUR BUFFERS: Both
the USDA and the state of Iowa
have cost share or financial
assistance programs to help
establish contour buffer strips,
says Phil Patterson.
Some farmers use the federal CRP to establish conservation buffers, but others use
the Iowa Buffer program from
IDALS.
“What some like about the
Iowa program is that they don’t
have to fence the buffers, and
they can hay and graze them
at specified times of the year.
They don’t get a payment every
year like they do for CRP, but
they do get an upfront $200-anacre incentive payment, and
they have only a five-year maintenance agreement in the Iowa
program,” notes Patterson.
While Patterson concentrates on trapping sediment
because that’s the goal of the
North Thompson project, he
knows keeping topsoil in place
on croplands is also a top goal
for farmers.
“I know farmers are concerned about sheet and rill
erosion. I was struck by a statement Dr. Elwynn Taylor, ISU
Extension climatologist, made
at a water conference last year.
He said we are experiencing
100-year storms every 17 years.
That’s on the minds of farmers,
too, because I hear them repeating that as they talk about
what they need to do to control
soil erosion on their land,” says
Patterson.
Betts writes from Johnston.