Initial research shows drying greenfeed with glyphosate before cutting
and baling may be viable.
“While a number of producers were using this method, neither they nor
one of the glyphosate manufacturers had any research data on the
practice,” said Lorne Klein, a rangeland and forage agrologist with
Saskatchewan Agriculture.
Advantages of drying greenfeed with glyphosate include:
- Perennial weed control.
- Elimination of weather loss in the windrow and the need to turn
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windrows after a rain.
- The ability to schedule harvest.
- Cutting with a swather instead of a haybine.
Disadvantages include the cost of glyphosate, need for a high clearance
sprayer and no regrowth for fall grazing.
Trials were conducted on farms in Wawota, Balcarres, Francis, Corning
and Carievale.
While the trials used Roundup, other glyphosate products registered for
pre-harvest use on livestock forage include Credit, Maverick, Vantage,
Renegade and Vantage Plus.
“Three sites of oats and one site of barley were sprayed with Roundup
at one litre per acre, and one site of oats was sprayed at 0.5 L per
acre,” he said.
“The stands at all sites were sampled for yield and quality at the soft
dough stage, then sprayed and sampled every four to five days until dry
for baling, about 14 to 18 days later.”
After spraying, dry matter yield increased slightly until dry enough
for baling, then it returned to pre-glyphosate levels.
From spraying to drydown, the crude protein decreased one to 1.5
percentage points, and the total digestible nutrients, or energy, of
oats increased six to eight percentage points. The economic trade-off
of these protein and energy changes is about equal at current feed
costs.
Klein said barley’s energy did not increase after glyphosate spraying,
but more trials are needed to determine if it reacts differently than
oats to this treatment. Producers have reported that yellowfeed and
greenfeed are equally palatable to beef cows and, in some cases, cows
eat the yellowfeed first.
“From the results of this trial, it appears that producers have a new
option for drying greenfeed before baling. If sprayed with glyphosate
and allowed to dry standing, the dry matter yield will increase
slightly or remain the same, depending on when the crop is cut. Cutting
the crop with a swather is not recommended until it is dry enough to
bale. Stems that are not crimped will take longer to dry in a windrow.”
Klein said the cost of herbicide and application can be justified by
selecting a field that requires perennial weed control, cutting with a
swather rather than a haybine and by the ability to schedule cutting
and baling.
But he emphasized that the results are based on only one year of data.
Similar trials are needed to confirm the yield and quality effects, to
look at whether barley is less suited to this practice than oats, and
to measure the effects after rainfall on the standing yellowfeed.
Saskatchewan Agriculture rangeland and forage agrologist Al Foster
agreed.
He conducted a trial in Nipawin last year to determine the change in
feed quality and quantity when a greenfeed cereal crop is sprayed just
before the soft dough stage with glyphosate and allowed to stand until
dry enough for baling.
Oats were sprayed with one L per acre of Roundup on Aug. 27, and yield
and quality samples were collected at four-day intervals from the time
of spraying. Lab analysis showed the quality and yield at each of the
clipping dates changed only slightly.
“This variability probably can be attributed to sampling variability
and not a result of the spray treatment. Quality and yield over the
10-day span of the project did not appear to be affected by spraying
Roundup on oat greenfeed in this project,” Foster said.
