water, getting good yields with irrigation
By TAM MOORE Oregon Staff Writer
Automated and, in some cases, radio or
cell-phone connected soil moisture systems
are under evaluation at UC Intermountain
Research and Extension Center. The devices
are grouped in a commercial potato field.
TULELAKE, Calif. — Water’s always been precious
to farmers of the Klamath Basin.
Two events, one recent history, the other a
near-certain future, turn up the pressure to
make every drop count. Information gathered here
may help farmers across the irrigated West. It
has practical use for basin farmers eligible for
special Klamath water-conservation cost-share
programs contained in the 2002 farm bill.
Dozens of experiments and tests of applied
irrigation technology fill plots at the
University of California Intermountain Research
and Extension Center located at Tulelake, just
one mile south of the Oregon border.
Superintendent Harry Carlson turned the
station’s late July field day into a mid-summer
seminar on practical irrigation.
The station is within the federal Klamath
Reclamation Project where the 2001 drought and
the federal Endangered Species Act combined in a
nationally publicized U.S. Bureau of Reclamation
repudiation of irrigation delivery contracts.
Uncertainty over water delivery continues within
Electricity to run agricultural pumps within the
Klamath Project comes with a discounted rate —
part of the 50-year federal energy license to
PacifiCorp. The power company says it has no
intention of repeating those rates as part of
the next hydroelectric system license due in
Figuring out how to control future electricity
cost is on the mind of most farmers these days,
and topic one for a special committee of the
Klamath Water Users Association.
Carlson began practical irrigation experiments
over a decade ago, aimed at better yields on
potatoes and onions, two of the basin’s highest
Said Carlson, the bottom line is that the best
irrigation schedule is a combination of
estimates for crop water use, actual measurement
of soil moisture and adjustments for actual and
anticipated local weather conditions.
“There is no silver bullet for irrigating in the
wind with solid-set sprinklers” when velocity
goes over 10 miles an hour, he added.
Research continues in 2004, including evaluation
of six potato varieties under different
irrigation routines, using solid-set sprinklers
spaced at 15-foot intervals. That’s half the
spacing used in most commercial farms, and a
chance to not only see growth response to water
but monitor incidence of disease related to
humidity beneath the leafy canopy of vigorous
There’s what may be the basin’s first trial of
buried T-tape drip irrigation beneath onions.
Kevin Stewart of T-Tape System estimates that
elsewhere 10,000 acres of onions, primarily in
Idaho, are dripped this season. Four Idaho
potato growers have indicated interest in trying
commercial-sized drip systems.
Stewart is working with the Tulelake station’s
Don Kirby, who heads up the farming crew. Kirby
said problems came in getting uniform seed
germination in a dry spring.
“I didn’t see water and I panicked, and really
poured on the water,” he said. “But the onions
did start emerging, and there was too much
water; they turned yellow (on the tops).”
Two of Carlson’s ongoing projects are evaluation
of sprinkler uniformity — how water is
distributed in windy conditions — and making
site-specific crop water models.
There are jokes about the “field of cans,” an
array of 400 No. 10 cans around a single
sprinkler head. Data collected there, and
matched with wind speed and direction recorded
by an adjoining weather station, is used to plot
actual water delivery.
“After 10 years I’ve finally got it right,”
Carlson said of the testing, overseen this year
by Jessica Horsley, a research assistant.
Water measured in low-tech tin cans, fed to
sophisticated computer programs, turns into
predictions of irrigation efficiency, at various
wind speeds and directions, for specific types
of sprinkler heads and nozzle sizes. Evaluations
of seven sprinkler types with 58 variations for
nozzle size or operating pressure and wind speed
are available. So are computerized graphs
predicting actual coverage of various solid-set
In a field of spuds growing under commercial
conditions, there’s an array of off-the-shelf
soil moisture sensors linked to electronic
reader systems. By mid-summer, evaluating three
different sensor manufacturer’s measuring
scales, Carlson said there’s consistent data
that relates to soil moisture collected by the
neutron probe, a standard device used by crop
researchers. Any one of the systems will do the
job, he said; it’s just a matter of getting
familiar with the electronic data offered by the
Tam Moore is based in Medford, Ore. His email
address is email@example.com.
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