Better overall silage with crop mixtures.
November 20, 2007 By Rosalie I. Tennison
It may sound simple, but research shows that growing two crops for silage leads
to higher yield and higher protein. Sheri Strydhorst, a doctoral candidate at
the University of Alberta, examined the benefits of mixing barley with pulses
and she got some encouraging results. In fact, the research was so favourable
she tried the most promising mix in field conditions on her own farm near Neerlandia,
"Our objective was to see if this is a productive option for forage growers,"
Strydhorst explains. "We wanted to see which pulse species and which production
system would work and if it would be feasible."
Strydhorst's team learned that, on average, field peas grown with barley produced
the greatest tonnage. In second place was a combination of fababeans and barley,
and a distant third was a mix of barley and narrow-leafed lupin. Several seeding
rates were tested for each pulse variety with barley cross-seeded at a rate
of 53 plants per square metre. The check plots were the pulse varieties grown
as monoculture at their recommended rates. The pulse varieties used in the tests
were Snowbird tannin-free fababeans, Arabella narrow-leafed lupin and Cutlass
"Our intention was to include pulse crops to see if the nitrogen fixing
properties of these crops would be a benefit, so we eliminated nitrogen fertilizer
application from the research and only fertilized with potassium, phosphate
and sulphur," Strydhorst explains. "We harvested the crop when the
barley was at the soft dough stage."
The measured results of the harvest indicated the total yield of biomass was
greater than the check anytime a pulse crop was included with the barley. On
average, the combinations of crops yielded 12.4 tonnes of dry matter (DM) per
hectare compared to the monoculture check which yielded 10 tonnes DM/ha. "We
learned that the field pea/barley combo yielded the best of the three combinations,"
reports Strydhorst. "In fact, this combination yielded better than the
average at 13.5 tonnes DM/ha."
Seeding rate was not found to be a factor in determining the total yield, according
to Strydhorst. "The best and most consistent seeding process is to use
the recommended monoculture seeding rates for the pulse crops and seed the barley
at a quarter rate," she says. The pulse seeding rate does determine the
amount of pulse in the harvested silage, she adds. On average, seeding at the
recommended monoculture seeding rate gave a 50 : 50 mix of pulse/barley in the
Strydhorst does not see any drawbacks for this method of silage production.
If growers do not have the right equipment to seed the two crops at once and
have to do the seeding operation in two passes, the cost in time and fuel to
make the second pass replaces the time and fuel costs usually required for nitrogen
application. The purchase price of the nitrogen product is eliminated from the
equation but there may be extra costs for seed when two species are grown.
One of the positive results of the research was the 'averaging effect' of growing
two species. Strydhorst says that on the high areas of the fields the barley
did better culturally, while the pulses were more vigorous in the low areas.
"Each species finds its niche growing conditions in this system,"
the researcher explains. "This helps maintain biomass and protein overall."
In the final analysis, Strydhorst says a monoculture silage field does not
provide the yield stability that the combination of barley and pulses offered.
While she did not consult with animal nutritionists to determine the best combination
for feeding, she sees some opportunity for shared research in this area. In
the field pea/barley combination, 67 percent of the final silage was field pea
with a protein level of 16 percent. Compared to barley grown alone for silage,
which yielded 12 percent protein, Strydhorst says the combination may well give
producers more of what their animals need nutritionally.
"The best combination overall was field peas and barley, which offered
good yield and protein," concluded Strydhorst. "Fababean might have
offered slightly better protein at 19 percent compared to the 16 percent of
the pea combination, but that might not be enough of an incentive when the field
pea combination offered a much better yield."
Growers looking for yield stability, reduced nitrogen costs and improved protein
in their silage may want to consider Strydhorst's proven combinations. -30-
|Table 1. Test seeding rates of pulse
|Seeding rate (plants/sq.m)