WINNIPEG – An Agriculture Canada researcher says farmers can double the
moisture in their soil by choosing chem fallow over tillage.
Brian McConkey of the Semiarid Prairie Agricultural Research Centre, in
Swift Current, Sask., said tilled fallow fields actually lost soil
water during the drought of 2001.
“Tilled fallow stored only 1.7 inches of water but the chem fallow
stored 3.2 inches by the end of 2001,” he said. “By April 2002, the
tilled fallow fields had only 0.4 inches more water than wheat
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The Swift Current centre has documented soil moisture levels during the
four drought years of 1984, 1985, 1988 and 2001. On average, chem
fallow fields have stored 0.9 inches more water than fields that had
been tilled three or four times.
In 2001, researchers found that one chemical application in May, along
with two tillage operations later, retained 0.6 inches more water than
fallow with three tillage operations.
Although it is generally thought that canola does not generate enough
crop residue, the researchers found that chem fallow after a canola
crop stored slightly more soil water than chem fallow after wheat.
They also found that chem fallow after flax can store about the same
amount of water as chem fallow after a cereal crop.
Chem fallow after a pulse crop is generally thought to be risky because
of the small amount of residue. However, Swift Current research found
the risk to be acceptable if the pulse crop had been direct seeded into
cereal stubble so the stubble would carry through into the fallow year.
“Chem fallow after a pulse stored slightly less water than chem fallow
after a cereal crop,” he said. “For example, in April 2002, the chem
fallow after pea had 0.4 inches less soil water than that after durum.”
Nitrogen left in the soil after fallowing on pulse residue is another
benefit. The Swift Current centre showed an average of 4.5 kilograms
more soil nitrogen per acre on pulse chem fallow compared to cereal
chem fallow.
Durum grown on pulse chem fallow land produced 2.7 bushels per acre
more with 0.5 percent higher protein, compared to durum grown on cereal
chem fallow land.
According to the Saskatchewan Crop Planning Guide, chem fallow costs
about $15.58 per acre in the brown soil zone, $16.30 in the dark brown
and $16.83 in the black soil zone, for an average cost of about $5.35
more per acre than tillage fallow. But McConkey said the extra $5 per
acre is insignificant when farmers are watching their soil blow away.
“During the spring of 2002, fields which were chem fallowed in 2001
generally did not see the severe wind erosion that occurred on fields
which were tilled fallow in 2001.”
