Colorado Water June 2005

• Year: 2005
• Title: Colorado Water
• Author: Water Center of Colorado State University
• Description: JUNE 2005 Issue
• Publications - Doc Type: Newsletter

decrease in the EC of the extract wa-
ters are apparent in the first six extrac-
tions. This result suggests that the EC is
1600
strongly influenced by sodium, which is
F
highly soluble. As the multiple extracts
1400D
o am
m
proceeded, minor decreases in the mag-
nesium concentrations occurred, but the
calcium concentrations are essentially
the same between the first extract and
the 141 extract, which suggests that the
E
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soils and EC are "buffered" by gypsum
and calcite mineral precipitates that
000
Ova
cannot be readily leached from agricul-
aaov
tural fields. Fourteen extractions were
not sufficient to decrease the extract EC
2O
significantly below 4 dS m-'. Implica-
tions of this research support leaching g
0 5 1,0 15 z
studies of soil cores by David Huber and
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Dr. Greg Butters. The data have not yet
EC {' }
been completely examined for manage -._
ment recommendations of calcium- salt
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affected fields.
160 upwear�
Testing of the EC laboratory methods
is on- going. Since there are manipula-
1200 V
tions to collected soil samples as part of
1000
developing saturated paste extracts, such
as drying, grinding and mixing of soils
an d pastes, there is a potential to influ-
6 +
ence the EC measurements. Grinding of
nodules of calcium sulfate, calcium car-
400 V v V
bonate minerals /precipitates and of soil
200
k
aggregates can increase the surface area
available for dissolution and thereby ..
change the overall EC measurement by
0 5 10 15 20
making more salts available for dis-
solution than are available in -situ under Figure 2. Sodium and calcium extract concentrations (mg/IL)
typically irrigation processes. Preliminary
data suggests that extract waters taken from soil samples
retaining their aggregates, and not stirred during the
saturation process, have a lower EC than those samples
that are manipulated. The use of surrogate irrigation
water in creating the saturated paste has preliminary
results suggesting that the EC between the soils and the
water is not additive. It is expected that the additional
tests may offer clues /answers as to the why and how the
two EC's become intermixed.
Planned analysis for Summer 2005, include, but are not
limited to:
1) Beta testing of an updated WATSUIT model by
Dr. Jim Oster, Emeritus Soil and Water Specialist,
University of California, Riverside.
2) Refining the calibration equations to the EM -38
electromagnetic sensor by utilizing chemical data.
Equations were created by James Wittler as part
of an ongoing Masters research at Colorado State
University.
3) Continue working with other researchers on efforts
related to salinity in the Arkansas River Basin. Data
has already been used to direct monitoring and mod-
eling efforts of Yaun -Win Lin and Roberto Arranz
(graduate students of Dr. Garcia). The implication
of the calcium chemistry /mineralogy in the soils has
_.. ____ 9