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<br />Water, salt mix, .~~
<br />researcher finds 'j~>
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<br />liy Michael Moss
<br />Sentinel staff \\,.ite.
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<br />Water a~d salt Since the first furrow.was plowejl,.
<br />farmers have tried to keep the two from mixirig. . . ;::
<br />The combination of the two. inevitably has but one:.:
<br />result: adecreasing productivity of soil and crop. ., .~.,
<br />Now, a California researcher for the U.S. Depart:; :
<br />ment of Agriculture h.as collected enough data to pro.'.;::
<br />pose a new perspective On the problem. ...' ,
<br />"It's still early to be conclusive," said Jim Rhoades:. '
<br />of the USDA's Salinity,Laboratory inll,iverside. "Butit'~:
<br />looks like the standards we've set for crop salinity fol:';'
<br />erance levels are conservative. It 1001\S like we can use :":
<br />water that's far more saline than we used to think." ::..
<br />Rhoades was reluctant to specify a new tolerance;"
<br />level. . ", " _ _:.. <;-
<br />But, he said the old standard:-rangingnearJ,ood~c
<br />parts per million or. milligrams per liter-could in:. ;.~
<br />crease six.fold in a reasonable new standard based op;."
<br />the iiTigation techniqUe that Rhoades is now perfect? '
<br />. . . -' . .,1.
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<br />Ifmany plants under marly conditions can indeed':':
<br />handle salt'levels near 6,000 ppm, the implicationS:.~;
<br />could spring Western, agriculture into a new bloom. :,,'
<br />No longer would farmers using Colorado River wa~;:
<br />ter.."now polluted with a range from 400 to 900 ppm of~;
<br />saltll-'-haveto worry about lacking usableiYater.':"
<br />Rhoades began his research with saline .irrigation. "
<br />watersix years ago in the San Joaquin Valley using ..
<br />cotton, \ I. :'"
<br />He then moved south to the Imperial Valley working.o
<br />with rotated croppings of lettuce, sugar. beets an<l':...
<br />wheat ' .
<br />What he has found is a willingness among plants t<l';~
<br />accept highly. saline water during certain periodsof".~
<br />theirgrowthcYCie; . . . .";h
<br />Starting with sugar beets, a fairly salt-tolerant cropi".
<br />he soaked the soil prior to planting with high qualitY::;:
<br />water. That flushed the soil of its lingering salts and" ~',
<br />startectthe sensitive seedlings off. . :;'
<br />He theil switche.d to highly saline irrigation runoff pO
<br />water to see the beets. through much of the!.r growth....
<br />cycle. "'::
<br />.t.,,!
<br />Next, lettuce was planted again with high quality wac!,;
<br />terand kept on the good stuff throilghout its growth,l ri
<br />Good quality water was used with the next planting, It"j
<br />switch to wheat. But later in the wheat's growth the.,"
<br />saline wastewater was again piped intothe.fields. J'.
<br />. 'The result: Goot! yields ofall three crops. .. 'n
<br />One drawback, Rhoades cautioned, could arise i(.<.,
<br />t'llrther testing shows thafthe water quality switchinll!
<br />requires more flushing of soils between crops. Tba![."
<br />cOllld increase a farmer's pumping costs. . ,..;
<br />.lIilt heremains 'optimistic. He e.stimated that so.uth:: .
<br />erll California irrigators using bis tecbnique could,,,; , .
<br />~1!se ; '!p to 80 percent of their own . ~alty ~rain8!leN4 \,
<br />. while farmers all along the Colorado River, mcludmgQ;<:
<br />t~GrandValley, would have less to fear of using salt~
<br />plllluted water.. C"~i
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