The Rural Voice, 2004-10, Page 42Advice
Recommended nitrogen rates may be more than needed
for corn, new 'greenhouse gas' study shows
Ontario corn producers who
follow standard recommended rates
of nitrogen application may be
applying more' than what is
considered optimal, says a field crops
specialist.
The discovery was made at the
start of a project evaluating different
soil nitrogen tests and application
rates in 2003, says Brian Hall with
the Ontario Ministry of Agriculture
and Food (OMAF). Results showed
that optimal fertilizer rates are less
than the standard recommended rates
most corn producers use.
"It may mean producers are able
to reduce nitrogen rates and in doing
so, there could be a lower risk of
surplus nitrogen being leached
through the soil or lost to the
atmosphere," says Hall.
Further evaluation of the fertilizer
application rates will continue
through to the 2005 growing season
on nine demonstration sites across
Ontario. The project is being partially
funded by the federal Greenhouse
Gas Mitigation Program for
Canadian Agriculture (GHGMP).
Soil Conservation Council of Canada
administers the soil and nutrient
management component of the
program. A longer report on this
project can be found on the SCCC
Web site at www.soilcc.ca.
The demonstrations involve
Farmers may be able to reduce
nitrogen appliciation rates for corn.
testing the soil using four different
nitrogen assessments: a pre -plant
nitrogen soil analysis; an in -crop test
called a pre -side dress soil nitrogen
test; a corn stalk nitrogen test that
measures nitrogen in corn plant tissue
near the end of the growing season;
and a fall soil test analysis. Hall says
nitrogen testing at various stages of
the growing season will provide a
clearer picture of the amount of
nitrogen actually available and used.
"Right now most producers are
following provincial recommend-
ations for crop nutrient requirements
and are also taking into account how
much nitrogen is in the manure that's
being applied," he says. "What most
producers are not taking into account
is the amount of organic nitrogen
that's mineralized in the soil during
the growing season."
The pre -side dress soil test may be
the one of the most valuable to
producers if it is proven to be
accurate, says Hall. The test is done
at the four -to -six -leaf crop stage to
show the amount of available
nitrogen in the soil. If the test is
accurate, producers will be able to
determine the amount of nitrogen
needed in -crop to support the corn
over the balance of the growing
season.
Checking nitrogen at various
stages will also help determine how
much surplus nitrogen is left in the
soil at various fertilizer rates. "The
tools may help producers reduce
application rates and input costs, as
well as the amount of surplus
nitrogen in the soil," says Hall.
The GHGMP supports a broad
range of projects across Canada with
the goal to promote awareness of
agricultural practices that reduce
gre' nhouse gas emissions. SCCC
administers the delivery of the soil
and nutrient management sector
component of the program. For more
information on activities, visit the
SCCC's Web site at www.soilcc.ca.0
Information on diseases that affect horses
By Dr. Robert Wright,
Veterinary Science
In the late spring, and more
recently in July, veterinarians
reported horses salivating profusely,
with saliva hanging from the mouth
and pooling on the floor.
Affected horses commonly show
no abnormal clinical signs except the
profuse frothy salivation. Slaframine
poisoning should be considered,
especially in a cooler and wetter
spring or fall when the clovers
proliferate in pastures.•
The cooler wet conditions are also
ideal for the growth of the fungus
Rhizoctonia leguminicola (black
patch). The fungus infects red clover
38 THE RURAL VOICE
(Trifolium pratense), white clover
(Trifolium repens), alsike clover
(Trifolium hybridum) and alfalfa.
The name "black patch" is derived
from the bronze -to -black spots or
rings observed on the leaves and
stems (1). The fungus produces the
mycotoxin slaframine or slobber
factor. It can be present on both
pasture and in stored dry hay. The
fungus persists on infected fields
from year to year. Slaframine can be
active in stored hay for 10 months or
more, however, its biological activity
does decrease. The analysis for
slaframine is not readily available.
Eastern equine encephalitis (EEE)
is a mosquito -borne disease that can
cause inflammation of the brain
(encephalitis). The virus causing
EEE belongs to the family
Togaviridae, which includes Eastern,
Western and Venezuelan equine
encephalitis viruses. Periodically,
EEE has been identified in horses
that reside in the province of Ontario
or have become infected while
travelling through other areas of
North America.
Other diseases/conditions that can
cause similar clinical signs include
rabies, West Nile virus (WNV)
infection, the neurological form of
equine herpesvirus.(EHV), equine
protozoal myeloencephalitis (EPM)
and botulism.°