With both extremely wet and dry conditions happening in the same growing season, it's not a stretch to call 2011 a strange year in Manitoba, but it has helped prove the effectiveness of perennial and annual forage seed blends known as “polycrops” or cover crops in dealing with extremes of weather.

“One thing that became very clear this year is that having something green and growing in the spring takes moisture out of the soil,” says Oliver Joslin, who farms near Rossburn, Manitoba. “I saw for myself how much better the soil is for having something growing on it as opposed to nothing at all.”

Although 2011’s fickle weather was tough on yields in many places, it’s provided a unique opportunity to really understand what happens under both conditions.

Seed blend

Joslin experimented with a polycrop for the first time on 25 acres and was one of two farmers who hosted summer field tours organized by the Manitoba Forage Council, Manitoba Grazing Clubs and Ducks Unlimited Canada in association with local holistic management clubs.

Initial work shows that plant diversity improved emergence and production of the polycrops. In addition, customized blends were created to address various soil issues.

For example, use of radish and turnip helped break down soil compaction and till layers. Polycrops in Manitoba are being explored to improve native pasture by providing complementary grazing, improve cattle gain and lengthen the grazing season.

“Cover crops improve soil health, increase organic matter and encourage microorganism activity that enhances nutrient cycling and the availability of nutrients for plant growth,” says Mike Thiele, Manitoba Grazing Club co-ordinator.

On his Rossburn-area farm, Joslin’s polycrop blend included 30 lbs of oats, 50 lbs of peas, one lb of turnips, 1 lb of forage radish and one lb of hairy vetch seeded directly into oat stubble the first weekend in June. No fertilizer was added apart from a starter mix at seeding. The crop received a light rainfall after seeding but then remained dry until late summer. Despite low growing-season moisture, the crop was lush and weeds were few.

Aside from providing good ground cover and using subsurface moisture, the polycrop also produced a valuable forage stand. Joslin’s option included strip grazing the field in the fall, baling the crop as feed, or harvesting what he estimated would be about 3,500 lbs of silage per acre.

Cost for the seed was around $250 for the 25 acres, which is fairly reasonable, says Thiele. “A polycrop doesn’t have to be expensive,” he says, adding overall input costs shouldn’t exceed $20 to $25 an acre and the seed mix can actually be any combination of seed a farmer may have lying around.

“The more diversity the better,” says Thiele. “The idea is to have lots of different species so the odds of getting good germination of some of them are better whatever the conditions.”

Several benefits

Diversity of plant species also helps prevent insect problems by discouraging the over-predominance of any one type of pest that typically occurs in a monoculture. Diverse root types help improve the water infiltration ability of soils.
“Using turnips and radishes in the mix, for example, is useful as each have different root types and they each occupy a different part of the soil profile,” says Thiele. “So it helps to break up hardpan and allow moisture to penetrate and move through the soil profile.” The root vegetables stay in the ground and decompose to also help build organic matter.
The concept of seeding a mixed blend polycrop has crept into Manitoba from North Dakota, says Ducks Unlimited agronomist Ken Gross. Gabe Brown, a beef producer near Bismarck North Dakota, developed the concept of a polycrop as part of his strategy to save his mixed farming operation after hail wiped out his grain crops in the mid-90s.

Brown says that when his lender pulled the ripcord after annual crops failed, he decided he might survive financially without cash cropping so he embarked on a wild venture to harvest everything with his cattle. His farm made a recovery that is nothing short of miraculous, now involving a rotation that encompasses crops purely for grazing, crops taken for silage or hay, and a few crops for grain again.

Brown’s grazing techniques are also highly advanced, using cells for super-efficient "harvesting" by the cattle, as well as stimulating growth of the perennials species used. The response of his soils and crop yields has been phenomenal, yet Brown experiments with scads of “crazy” new ideas all the time. “We try to fail on at least one thing every year,” he says.

Gross says while the concept of a diverse mixed stand makes sense, the challenge may be to find a combination of crops that do well in the Manitoba climate.

“One advantage they have in North Dakota is a longer growing season than we have here in Manitoba,” says Gross. “Some of the cooler season crops like annual cereals do well, but some other species such as hairy vetch are warm season crops that may not work every year.”

The crop blend can be designed to address specific objectives on each farm. It can be tailored to use up excessive moisture, include plants with root systems that help break up hardpan or compaction layers, help fix nitrogen in the soil, and contribute to improving soil organic matter.