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The INDEPENDENT, June 21, 2007
Can You dig It?
Schann Nelson, our garden columnist, is taking this week off while she recov-
ers from a misstep that twisted a joint in the wrong direction. Schann should be
back at her computer for The INDEPENDENT’S July 19 issue.
Meanwhile, this seems like a good opportunity to remind readers of the great in-
formation available from Oregon State University’s Extension Service. It’s all avail-
able on line at http://extension.oregonstate.edu/
HOW TO MAKE THE MOST OF THE WATER
ALREADY IN THE SOIL, NATURALLY
By Davi Richards
al, it’s becoming a more common practice as water and energy become scarcer.
In the Pacific Northwest, where most of our precipitation comes in the winter and
where summers in areas of rain shadow can be very hot and dry, it’s more of a chal-
lenge. But even here there are ways to take advantage of the moisture stored in the
soil if you know some basics, says Cassidy.
While there’s not a lot you can do about the soil conditions deeper than a foot or
at most a few feet where you garden, there’s a lot you can do at and near the sur-
face, where all the evaporation takes place.
The most obvious and effective step is to apply a generous layer of mulch, which
moderates the temperature of the surface soil by shielding it from the direct sun.
The lower the temperature is, the slower the rate of evaporation.
Because there’s reduced connectivity between the mulch and soil, the moisture
in the soil doesn’t wick well across that interface to reach the surface of the mulch,
where it would evaporate more rapidly. Moisture vapor still moves upward through
the mulch, but this process is much slower than migration through capillaries.
Plus, over time, organic mulches improve the overall quality of the soil.
The best time to apply mulch, says Cassidy, is at that time in the spring when the
net movement of water entering the soil from the winter precipitation is about to be-
come less than the moisture leaving by evaporation and plant use. Since home gar-
deners need to guess at this time, he recommends being on the safe side and put-
ting mulch down before the surface of the soil dries out completely.
Tilling can also affect water migration and evaporation in several ways. On the
one hand, tilling encourages the topmost layer of soil to dry out quickly. On the oth-
er hand, once you have a thin layer of fine dry soil, it may itself act as a “dust mulch”
by breaking the connectivity with the lower soil and moderating its temperature. Re-
peated tilling can cause a condition called “plow pan,” in which the layer of soil just
at the bottom reach of the tilling equipment becomes compacted and no longer
readily absorbs water from either irrigation or precipitation.
Cassidy recommends tilling as little as possible. Start vegetables indoors and
transplant them outside when they’re big enough. People who till an entire bed suf-
ficiently for very small seeds to germinate well, are probably wasting time and en-
ergy, encouraging evaporation, and making the whole process more complicated
than it needs to be.
Finally, stay off your gardening spaces. That footprint in the soil of your garden
bed not only looks careless. It also establishes good connectivity in the soil at that
spot, so water may reach the surface and evaporate more quickly.
Looking ahead to what may become drastic climate changes, most gardeners al-
ready recognize their responsibility to conserve water and energy. Since energy is
needed both to treat and distribute water, cutting down on the water you use in the
garden also saves energy.
One source of water that’s often overlooked by gardeners is the moisture that’s
naturally stored in the soil. To make the most of this water, it helps to understand
how it gets there and how it moves through the soil.
“Think of the soil as a storage medium,” said James Cassidy, soil scientist at
Oregon State University. “Precipitation is periodic, but plants need water all the
time. As a plant uses up the moisture near it, more water stored in the soil moves
in.”
How does this happen? Liquids move naturally into tiny spaces even against the
force of gravity. Think of how the blood from a pinprick in your finger moves up
through the little glass tube at the doctor’s office. This force is called “capillary
force.” It’s what causes moisture in the soil to move into the minute spaces where
the soil is drier. As long as there is “connectivity” in the soil, that is, as long as the
spaces in the soil are connected to form tiny capillaries that the water can rise into,
moisture will continue to move toward the surface to replace water that’s lost there
through plant use and evaporation.
Different kinds of soil provide different conditions for this movement. Clay soils,
made up of extremely fine particles, have numerous and extremely fine capillaries.
So clay soils hold water well and dry out more slowly than sandy soils, with their
larger particles and larger spaces. Generally, water moves more slowly through
clay soils and faster through sandy soils.
Ideally, if you live where the soil is deep and uninterrupted by rocky layers, your
soil can be kept moist all summer as water migrates upward from the water table
(the depth at which the soil is saturated.) As your plants use the moisture near the
For information on a wide variety of garden topics, go to the OSU Extension Ser-
surface and as moisture evaporates from the surface soil, more water wicks up- vice website: http//extension.oregonstate.edu/
ward by the capillary force and naturally waters your plants. In ideal conditions, this
water can be enough to see some plants through the growing
season.
“Dry farming, farming without irrigation, is more common in
parts of the world where there’s some precipitation during the
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A SSEMBLY OF G OD
growing season to supplement the moisture stored in the soil. In
parts of the Midwest, for instance, where summer storms are usu-
Gary Taylor, Pastor
Rev. Luan Tran, Administrator
Wayne and Maureene Marr
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Sunday School 10:00 a.m.
Morning Worship 11:00 a.m.
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Wednesday Service 7:00 p.m.
960 Missouri Avenue, Vernonia
503 429-8841
Mass Schedule
Sunday 12:00 Noon
Religious Education
Sunday 10:30 a.m.
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John Aitken II, Pastor, 396-1856
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503 429-8301
Morning Worship, 9:15 a.m.
Bible Study 10:30 a.m.
Carl Pense, Pastor
850 Madison Avenue, Vernonia
503 429-1103
Sunday Worship Service: 10:30 a.m.
Children’s Sunday School
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Grant Williams, Pastor
957 State Avenue, Vernonia
503 429-6790
Sunday Breakfast 9:00 a.m.
Morning Worship 9:45 a.m.
Children and Nursery 10:00 a.m.
Youth Group 6:00 p.m.
Preschool Tues. & Thurs. 9:00 a.m.
Wednesday Prayer 7:00 p.m.
Friday Adult Volleyball 7:00 p.m.
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Sunday School 9:45 a.m.
Sunday Worship Service 11:00 a.m.
Wednesday Prayer Meeting 7:00 p.m.
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375 North St. (Vernonia Grange Hall)
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Please call for service schedule.
662 Jefferson Ave., Vernonia,
503 429-0373
Sunday School 9:45 a.m.
Morning Worship 11:00 a.m
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Sam Hough, Evangelist
410 North Street, Vernonia
503 429-6522
Sunday School 9:45 a.m.
Morning Worship 11:00 a.m.
Every Wednesday:
Ladies' Bible Study 9:30 a.m.
Ladies’ Worship 10:00 a.m.
Children’s Choir 3:00 p.m.
Family Bible Study 7:00 p.m.
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OF L ATTER D AY S AINTS
Jeff Cheney, Branch President
1350 E. Knott Street, Vernonia
503 429-7151
Sacrament Meeting, Sunday 10 a.m.
Sunday School & Primary 11:20 a.m.
Relief Society, Priesthood and
Young Women, Sunday 12:10 p.m.