AC Yellowhead was bred in Saskatchewan at AAFC Research Centres, where it was found the variety was ideal in grass mixtures and under heavy grazing. In fact, the development of AC Yellowhead was preceded by grazing trials which showed the yellow blossomed alfalfa had the greatest persistence among wheat grasses and bluegrass compared to other purple-blossom varieties. Later trials from the University of Minnesota showed that AC Yellowhead performed well in the face of low precipitation, yielding 20% more than the next highest variety tested. This variety has also had a 1-2% higher protein content than other varieties of alfalfa. Nevertheless, AC Yellowhead has not yet been widely adopted.
The Saskatchewan Forage Council, as part of the Saskatchewan Ministry of Agriculture’s Agriculture Demonstration of Practices and Technologies (ADOPT) program, conducted a trial beginning in 2014 across the province to demonstrate AC Yellowhead alfalfa’s establishment, winter survival, and persistence in forage stands.
Demonstration plots were seeded in the summers of 2014 or 2015 near Lestock, Swift Current, Rosetown, and Smeaton. All four sites incorporated a brome grass (which differed only by location), with a comparison plot featuring the same type of brome grass, and a purple-blossomed alfalfa appropriate for that region.
The most successful establishment was located near Rosetown. Both varieties of AC Yellowhead alfalfa and purple-blossom alfalfa were well established. However, the AC Yellowhead variety yielded only 92% compared to its counterpart and was approximately six inches shorter during harvest, while appearing denser. The AC Yellowhead variety showed better crude protein and fiber value as well as slightly higher levels of calcium, phosphorus, and magnesium. The purple-blossom variety was higher in TDN and energy.
The Smeaton site, located at the Smeaton Community Pasture, had some difficultly in its establishment due to a late seeding date at the beginning of August, and broadcast seeding into a stand that had not been fully terminated. Elk then grazed in the winter of 2014-15, a critical time of establishment, which did not allow the root reserves to be re-established for winter survival. The purple-blossom alfalfa showed a higher plant count than AC Yellowhead alfalfa in 2015, and the AC Yellowhead alfalfa yielded only 60% of the purple-blossom variety. In the following 2016 year, the AC Yellowhead variety was leafier and denser, which increased yield to 156% of the purple-blossom variety.
The Swift Current site did not have any alfalfa, whether the purple-blossom variety (Runner) or the AC Yellowhead variety due to a low seeding rate, very little rain in that year, and the marginal land it was planted upon.
The Lestock plot, located at the Ducks Unlimited Touchwood Hills Conservation Ranch, was not able to seed in 2014, the initial year, due to excessive moisture. In the following year, the purple-blossom variety appeared more vigorous, and was taller. The AC Yellowhead variety yeilded only 66% of the purple-blossom alfalfa variety, though they had a higher seeding rate. Alfalfa weevils also affected the stand which prompted the producer to cut the stand earlier than normally expected to prevent greater losses.
And the results are…
While we all hope to have precise results with information that can help producers improve pastures, plot trials are not always helpful, and don’t always occur during years with the best conditions. These plot demonstrations were affected by drought, insects, and uncontrollable grazing patterns – something all producers face. These results may not be similar to the AC Yellowhead already in pastures around the province due to these circumstances.
The four plots from across the province showed great differences in establishment due to circumstance and precipitation. Where this variety of alfalfa did establish itself, it was noted to be leafy but with smaller leaves, shorter, and finer. It also tended to mature later than purple-blossom varieties, and yielded less than the purple-blossom variety in all applicable locations except at the second year of the Smeaton site. AC Yellowhead might be better adapted to the Rosetown area, where it thrived compared to the purple-blossom variety. There was also no proof that this variety could better survive winter.
Read more about the full results here.
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