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University of
Idaho researchers are working with growers to find ways to have
more crop rotation options, better management for rotations and
increased crop residue during critical erosion times. Increasing
crop residue is instrumental in reducing erosion, but can increase
disease, weed and insect problems. Increased crop rotation can reduce
these pest problems. Rotation crops need to be profitable, beneficial,
flexible, provide adequate crop residue and their effects need to
be best managed in the crop that follows. Extension workers and
researchers have conducted eight field trials evaluating rotation
crops, the impact of these crops on a following wheat crop, crop
residue production by rotation crops and N fertility responses in
the following wheat crop.
Canola, winter
rapeseed, crambe, condiment mustard (four Brassica crops), pea,
lentil, spring barley and wheat are all potential rotation crops
before wheat. Wheat almost always yielded most following pea or
lentil and compared to pea, wheat yield after wheat was 76 percent
as much, 84 percent as much following barley, and 91% to 99% as
much following Brassica crops. When N fertility was increased, these
differences were less compared to pea. At low fertility, wheat following
Brassica crops appears to need less N fertilizer. Pea and lentil
are excellent rotation crops for winter wheat, but provide very
limited crop residue for the critical erosion period following winter
wheat seeding and establishment.
Average annual
soil losses of 9 to 35 tons per acre can occur in winter wheat after
pea or lentil. Increasing the ground cover by using higher residue
rotation crops, such as the Brassica crops, should reduce this soil
loss by more than half. Mustard as an alternative rotation crop
should allow low crop inputs of fertilizer and pesticides and provide
ample residue for erosion control. Efforts to develop a practical
and profitable way to crop mustard in the area is ongoing. There
is a potential of growing 100,000 acres of mustard in the region,
and if Canola and industrial quality mustard is available, acreage
could be increased even more.
For more information, contact: Stephen
O. Guy
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