The Cross Section, Volume 24, Number 8, August 1978 Page: 1
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AGRICULTURAL
_ SlrtilPublished monthly by High Plains Underground Water Conservation District No. 1, 2930 Avenue Q, Lu
Volume 24-No. 8 Publication number 564920, Second Class Postage paid at Lubbock,
Agricultural Water Quality .
MdUNICIPAL
/( LLLL
_ _ '4LL
dEN L Lbbock, Texas 79405
Texas August, 1978
Evaluated
by D. D. Smith
The High Plains irrigator has been
blessed with water of such chemical
quality as to be almost perfectly com-
patible with the various soils upon
which it is applied. Natural recharge
to the Ogallala aquifer must, and has
in the geologic past, come from pre-
cipitation which has filtered down
through the rocks of the OgallalaGroup. As the infiltrating water passes
through the soil and rock column, it
dissolves minerals from the rock matrix
in such proportions as to establish a
chemical equilibrium.
In making an assessment of the
chemical compatibility of the water
with the soil for sustained irrigated
agricultural usage, potential problem
development might be conveniently
grouped into the broad categories of
Salinity, Permeability and Toxicity.
In this issue of "The Cross Section"
the maps presented on pages two and
three depict the areal distribution and
quantitative values for Specific Electri-
cal Conductance and the Sodium Ad-
sorption Ratio. Traditionally, the char-
acteristics of water used to adjudge its
suitability for irrigation have been the
total concentration of salts indicated by
the specific electrical conductance, the
percentage of sodium, and the boron,
chloride and sulfate concentrations.
Since all of these factors may vary over
considerable ranges independently of
each other, the suitability of the water
for irrigation must be judged on
analysis of the specific chemical con-
tent as well as the total concentration.
A salinity problem related to water
quality occurs if the total quantity of
salts in the irrigation water is high
enough that salts accumulate in the
crop root zone. As excessive quanti-
ties of soluble salts build up in the
root zone, the plant has added difficul-
ty in extracting sufficient water from
the soil solution. The electrical con-
ductivities and total dissolved solids
contents of soil solutions have been
found to be sufficiently well related totheir osmotic pressures to allow the
substitution of electrical conductance
for the more involved determination of
osmotic pressure. Electrical conduc-
tance is defined as the ability of a
substance to conduct an electric cur-
rent. Specific Electrical Conductance is
the capability to conduct electricity of
a cube of the substance one centimeter
on a side, and for uniformity of report-
ing (in the case of water) at a standard
temperature (77 degrees F). Keeping
in mind the probability that salinity of
the soil moisture may be five to ten
times higher than the salinity of the
applied irrigation water, osmotic pres-
sure - 0.36 x (electrical conductivity
of the soil extract x 103).
A permeability problem related to
water quality occurs when the rate of
water infiltration into and through the
soil is reduced by the effect of specific
salts or lack of salts in the applied
water; therefore, the evaluation of the
total salts in the water is essential.
Low salt content can result in poor soil
permeability due to the capacity of
pure water to dissolve and remove
calcium and other solubles in the soil.
A comparison of the relative content
of sodium to calcium and magnesium
in the water is also essential. Calcium
and magnesium in the proper propor-
tions maintain soil in good conditionof tilth and structure, while the oppo-
site is expected when sodium predomi-
nates.
The USDA Salinity Laboratory (1954)
defined sodium-adsorption-ratio (SAR)
(Na +)
of a water as SAR= V (Ca+2) + (Mg+2)
2
where ion concentrations are ex-
pressed in milliequivalents per liter.
Experimentation indicates a good pre-
dictability of the degree to which irri-
gation water will tend to enter into
cation-exchange reactions in soil. High
values for SAR imply a hazard of
sodium replacing adsorbed calcium
and magnesium, such replacement
having the potential to damage soil
structure and tilth as previously out-
lined.
A diagram used widely for evalu-
ating the potential of waters for irriga-
tion was published by the USDA
Salinity Laboratory (1954) and is repro-
duced with the maps. The specific
conductance (used as an index of the
dissolved s o I i d s concentration) is
plotted on the horizontal scale and
the SAR on the vertical scale. The
diagram is divided into 16 areas which
are used to rate the degree to which a
continued on page 4... WATER QUALITYNumber Of Permits Declines
Through the first six months of economy. For instance, in 1977,
1978, only 350 well permits have only 819 permits were issued-the
been issued. This appears to be an smallest number of permits since the
extension of a trend. The number District was formed in 1953. The
of permit applications closely parallels following table shows the 1977 figuresthe condition of the general farm in detail.
Permits Issued New Wells
in 1977 DrilledReplacement
Wells DrilledCounty
Reported
Dry HolesTAES Field Day
Set For Sept. 12
The public is cordially invited to
attend the 69th Annual Field Day being
conducted at the Halfway Texas Agri-
cultural Experiment Station, which is
located 14 miles west of Plainview, on
September 12, 1978, according to Dr.
Bill Ott, Superintendent of the Lub-
bock and Halfway Stations. Activities
for the field day are scheduled to be-
gin at 1:00 p.m.
This year's activities at the Halfway
Station will highlight such topics as
weed control, mobile trickle irrigation
systems, corn irrigation, cotton varie-
ties and a discussion on farm labor
management. Station specialists will
be on hand at demonstration locations
for discussion of the demonstration as
well as to answer questions related to
specific problems within their area of
expertise. There will also be agricul-
tural implement displays and exhibits
on the station grounds for public view-
ing following the field tour.
The field day program is a coopera-
tive effort of the TAES, the High Plains
Research Foundation, the Science Edu-
cation Administration of the U. S. De-
partment of Agriculture, the National
Weather Service, the Texas Forest
Service, and the Texas Agricultural
Extension Service.
PARMER OFFICE MOVED
Mr. Clayton Williamson, City Man-
ager of Bovina, will become the new
County Secretary in Parmer County for
the High Plains Underground Water
Conservation District No. 1 effective
August 21, 1978.
The new office location will be in
the Bovina City Hall at 323 North
Street, phone number 238-1116. Allbusiness pertaining to well permits, or
other such activities, will be handled at
this new office. The office will be
open from 8:00 a.m. to 5:00 p.m.
Monday through Friday.BOARD DISCUSSES
"ABANDONED WELLS"
The Board of Directors of the High
Plains Underground Water Conserva-
tion District No. 1 postponed action on
defining terms and adopting proce-
dures for declaring well sites aban-
doned at their August meeting.
In-depth discussions of the impact
of declaring well sites abandoned filled
much of the morning. The guidelines
to be established by this action will
be of increasing importance as new
applications are made for wells at or
near "abandoned well" sites. The
Directors clearly stated that they do
not want to approach a solution which
would deprive any landowner of good
and valuable property.
The Board concluded that theycontinued on page 4... BOARD MEET TOTAL
Armstrong
Bailey
Castro
Cochran
Crosby
Deaf Smith
Floyd
Hale
Hockley
Lamb
Lubbock
Lynn
Parmer
Potter
Randall1
76
113
22
3
127
83
26
39
131
72
16
93
17
81960
101
24
3
102
67
23
39
113
59
6
117
16
7313
1
1
2
i
5
28
4
2
9
11
2
1
11
3
1
11
1
6415
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High Plains Underground Water Conservation District No. 1 (Tex.). The Cross Section, Volume 24, Number 8, August 1978, periodical, August 1978; Lubbock, Texas. (https://texashistory.unt.edu/ark:/67531/metapth1533041/m1/1/: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting UNT Libraries Government Documents Department.