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SAR
SAR
is the Sodium Adsorption Ratio and it is used to determine
if soil or irrigation water has too much sodium. Chlorides,
salt, can kill plants (chlorides restrict the ability of plants
to get water) or prevent seeds from germinating, but sodium's
effect is isn't so obvious.
Sodium,
if there's enough of it, negatively affects the soil and also
plants' growth. In West Virginia, with its low soil pH, the
negative soil effects of high sodium (crusting, imperviousness
to water) are less prominent, but too much sodium impedes
plant growth (sodium affects how plants get their nutrients).
SAR
is used to measure sodium in soils (and irrigation water)
by examining the relationship of three ions -- sodium, magnesium
and calcium. A Colorado
State University Extension Service Bulletin gives a good
description of SAR and what it means. The formula for determining
SAR is fairly complex but the Extension
Service also has a page that explains how to determine
SAR and has an online computer for SAR. We've only seen a
couple soil samples for West Virginia with quantities of sodium,
calcium and magnesium, and those samples' SAR values were
less than 0.25. For liquid pit waste in West Virginia, we
have only the results of sampling 5 pits made in the 1980s.
The SAR values for those pits ranged between a "low"
of 6.89 to a high of over 32. We have on this website an Excel
workbook with a SAR computer and also a worksheet giving some
of the constituents in those West Virginia pits. For irrigation
water, a SAR of 3 to 9 is a slight to moderate hazard.
A SAR over 9 is considered an acute hazard.
There
is no way to know, because the state doesn't require testing
for it, just how much sodium was in the waste landsprayed
at Fernow. Nor do we know what the SAR was (if the reader
takes a few minutes with the SAR computer download, they'll
discover that increasing the calcium level, lowers the SAR;
a mitigating factor for the Berry Energy well at Fernow may
be that the site was on a limestone, calcium carbonate, rather
than sandstone ridge). But if the sodium level was high, if
the SAR was high, then there will be long-lasting effects
on vegetation including trees.
Just
like chlorides, the issues surrounding sodium are how high
the amount should be in liquid waste and how much should be
sprayed over how large an area. With the amounts of waste
fluids created in drilling and fracturing wells on the increase,
the issues of chlorides and sodium/SAR become even more important.
We
think that the state should test the soil before landspraying
and afterwards. We also think there needs to be limitations
on receiving soil final SAR level and liquid waste to be landsprayed
SAR level. In lieu of SAR testing, the state should determine
a maximum sodium load per acre. Saskatchewan's
is 250 kg/ha (222 lbs per acre).
The
next chapter discusses how pit waste is treated before landspraying.
Go
to Liming the Pit chapter.
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