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Alfalfa… A Research Roundup

The benefits of using alfalfa in a grazing system far outweighs the risks. With proper management one can keep losses at a very low level,” says Paul McCaughey former forage beef research scientist at Agriculture and Agri-Food Canada Brandon Research Centre. During his years at Brandon, Paul was instrumental in developing grazing systems that utilize the benefits of alfalfa. He is now the science director for the Saskatoon and Lacombe research centres.

“Grazing animals need to be full at all times and if you move the cattle on to new alfalfa-based pastures when they are hungry then you will have problems. It is best to move the animals to the next pasture in the afternoon when they are full,” he says.

A 10-year study at Brandon found alfalfa-grass pastures could be twice as productive as grass pastures without added fertilizer. Fertilized and unfertilized rejuvenation treatments on meadow brome and mixed alfalfa-meadow bromegrass stands were compared over the decade. Only alfalfa-grass pastures yielded a net profit.

Shannon Scott a research scientist at Brandon concluded that while converting poor soils from cropland to perennial pasture may improve the soil health and reduce erosion, it is not always profitable unless the pasture is improved by adding either alfalfa, another legume or commercial fertilizer.

The pastures at Brandon were seeded with three pounds of alfalfa and six pounds of meadow bromegrass seed. In the initial years the pastures were mostly alfalfa but over time the stand stabilized to about 40 per cent alfalfa. The alfalfa-grass stands were grazed when they were 18 to 20 inches high. McCaughey noted that when there was lots of alfalfa the cattle would seek out meadow bromegrass to eat and when there was lots of grass the animals would look for alfalfa to graze. At Brandon they had very few cases of bloat as the cattle were basically able to consume both grass and alfalfa while they grazed.

Walter Majak and Doug Veira had similar results in bloat trials at Kamloops research station. They concluded that the incidence of frothy bloat was significantly reduced when grass was a component of the pasture but given a choice the alfalfa was preferred over grass by the grazing animal.

Vern Baron a forage research scientist at Lacombe has done a lot of grazing research utilizing alfalfa in pure stands and mixtures with bromegrass. He says alfalfa longevity is a critical issue in the Western Parkland and Peace Region of Alberta. “Most varieties don’t have adequate winter hardness for intensive grazing systems,” says Baron.

The critical period for alfalfa in this region to replenish carbohydrate and protein root reserves is between the last week of July and first week of September. No cutting or grazing can occur during this period if you want to retain rapidly growing alfalfa plants over two years of age. Insufficient root reserves hamper the plant’s ability to survive the winter, and compete with rapidly growing grass plants like meadow bromegrass.

The drier climate of central Saskachewan and eastern Alberta allows alfalfa plants to make the physiological changes in the root and crown cells to survive cold temperatures and winter dormancy. The moister conditions in northwestern Alberta are more problematic. Researcher Jim Mackenzie working out of Beaverlodge in the 1970s and ’80s recorded alfalfa’s sensitivity to wet falls and fluctuating winter temperatures. Especially warm temperatures in late winter that bring alfalfa out of dormancy and leave plants susceptible to sudden cold snaps.

In general, Baron says conditions favouring rapid regrowth in late summer, which are good for grazing, predispose alfalfa plants to winterkill. “It’s the regrowth that does the damage,” he says. “Falcata types like AC Yellowhead are good for long-term pasture as they are very winter hardy and don’t produce a lot of regrowth in the fall by using up the carbohydrate reserves.” Anik, a variety grown in the Peace River region of Alberta, is an example of a cultivar with relatively slow growth and good winter survival. Anik grows well under the long photoperiods of the Peace and has a low crown.

After the critical period alfalfa can be grazed and Baron found that the normal grazing season could be extended by 45 days until late October at stocking rates similar to those used in summer. In these pastures alfalfa content remained as high as 60 per cent for seven years.

Baron found that a fertilized old grass stand consisting of Kentucky bluegrass, smooth bromegrass and quackgrass was equivalent for beef production to a fertilized meadow bromegrass stand grazed from June until mid-September. However, the old stand could only produce 34 per cent as much beef per acre as a meadow bromegrass-alfalfa stand, when both were cut as hay in July, stockpiled or rested until mid-September and then grazed from mid-September until

November. The extra fall production by the meadow brome-alfalfa mixture reduced the cost of stocker beef production in a summer-stockpiled grazing system versus grazing meadow bromegrass only in summer from $1.06 per head per day over 91 days and 198 pounds per animal during summer grazing to $1.01 per head per day over 131 days and 307 pounds per animal.

The alfalfa also contributed to N-fixation in the pasture. “We found that in a meadow bromegrass-alfalfa mixture with 40 per cent alfalfa: the alfalfa fixed about 90 kg/ha N and left about 38 kg/ha annually in the roots and litter for uptake by the grass component. In doing so we would have saved the equivalent of in excess of 100 kg N/ha of fertilizer-N.” This was similar to the Brandon findings.

Swift Current forage researcher Paul Jefferson who is now the director of the Western Beef Development Centre at Humboldt, Sask., found the more winter-hardy Canadian alfalfa varieties such as Beaver, Rangelander and AC Grazeland were less susceptible to the critical period and winterkill. Unfortunately, as winter hardiness increased yields went down, but Canadian seed companies are working on new winter-hardy varieties with higher yields.

“Alfalfa also has a role in rotational cropping systems,” Jefferson added. “Grain producers can use short-rotation alfalfa grass hay crops in their annual crop rotations where they have local markets for cash-crop hay and capture N benefits in subsequent grain crops.

“Alfalfa is still the most widely adapted legume we have and it will respond across a wide variety of soil types,” Jefferson found alfalfa could be grazed late in the fall with basically no nitrate problems. When the frost hits the plant carbohydrates stopped moving so no nitrates were produced. However, alfalfa doesn’t hold its forage quality after a frost so it is best when grazed earlier in the fall.

For the past six years I had a winter grazing trial at Lacombe utilizing meadow bromegrass and alfalfa. The pastures had been hayed in early July and our cows grazed regrowth through the snow until early March. Upon entering a new grazing area the cows would first graze the tops of the alfalfa plants before going for the meadow bromegrass. However the alfalfa was mostly dried stems and the cows didn’t consume this material. We had no evidence of winterkill under this grazing management system over the years but I would recommend that alfalfa meadow brome be grazed earlier in the fall for better utilization.

In Eastern Canada at the Agriculture Canada research centre at Sainte-Foy Quebec, plant physiologist Gilles Belanger urges producers in that part of the country to choose a recommended alfalfa cultivar with good winter tolerance. In his area Gilles has found cold periods in the fall (below 5 C) are required for alfalfa to develop tolerance to cold temperatures. Conversely, warm fall temperatures or thawing in winter can reduce the level of cold hardening.

A snow cover of 10 cm or more protects against very low winter

peratures. The presence of stubble in the fall aids in the accumulation of snow.

Soil fertility, particularly potassium, also plays an important role in cold hardening and alfalfa survival. Frequent harvests and harvests at early stages of development increase the risks of winter mortality. Excessive soil water content in the fall can also reduce the level of cold tolerance. On some soil types, high soil water content in the first 10 cm can cause heaving when freeze-thaw cycles occur. The presence of ice sheets allows the development of anoxic conditions, mostly on poorly drained soils. “Fall cutting increases the risk of winterkill and decreases regrowth in the following spring,” says Belanger. If fall cutting must be done, extending the interval between the last harvest and the one preceding it by 500 degree-days (about 50 days) reduces the risk of winterkill and may have a positive effect on regrowth in the following spring.

Arvid Aasen and Myron Bjorge both retired Alberta forage specialists have written a new ALBERTA FORAGE MANUAL which includes a large section on alfalfa. In addition there is a new booklet on sod seeding alfalfa available from the Manitoba Forage Council. Other information on the benefi ts of alfalfa can be found on

Duane McCartney Is A Retired Forage Beef Research Scientist From Lacombe, Alta.

peratures. The presence of stubble in the fall aids in the accumulation of snow.

Soil fertility, particularly potassium, also plays an important role in cold hardening and alfalfa survival. Frequent harvests and harvests at early stages of development increase the risks of winter mortality. Excessive soil water content in the fall can also reduce the level of cold tolerance. On some soil types, high soil water content in the first 10 cm can cause heaving when freeze-thaw cycles occur. The presence of ice sheets allows the development of anoxic conditions, mostly on poorly drained soils. “Fall cutting increases the risk of winterkill and decreases regrowth in the following spring,” says Belanger. If fall cutting must be done, extending the interval between the last harvest and the one preceding it by 500 degree-days (about 50 days) reduces the risk of winterkill and may have a positive effect on regrowth in the following spring.

Arvid Aasen and Myron Bjorge both retired Alberta forage specialists have written a new ALBERTA FORAGE MANUAL which includes a large section on alfalfa. In addition there is a new booklet on sod seeding alfalfa available from the Manitoba Forage Council. Other information on the benefi ts of alfalfa can be found on www.Foragebeef.ca.

Duane McCartney Is A Retired Forage Beef Research Scientist From Lacombe, Alta.

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Duane McCartney is a retired forage-beef systems research scientist at Lacombe, Alta.

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