Soil health could present key to yield growth

Clearwater County establishes cover crop trials to see what might work in a region that has an unpredictable climate

ROCKY MOUNTAIN HOUSE, Alta. — Taking care of soil health could become the next green revolution.

Agriculturalists are cognizant of soil chemistry but know less about the biology, said Ken Ziegler of the Grey Wooded Forage Association.

“The reality is soil biology has a very important part to play in the health of the soil from a chemistry perspective and from a physics perspective,” he said during an agricultural tour of Clearwater County in west-central Alberta.

“We have to begin to learn soil biology, and how do we manage our soils to enhance the soil biology so we can farm the soil in a sustainable way for a long time,” he said.

The county has established cover crop trials to see what might work in this region with grey-wooded soil and an unpredictable climate as the fields tilt upward toward the foothills.

This year, the region has received about 85 millimetres of rain since June so pastures are drying up and harvest is early.

In those challenging years, soil health is critical.

“Soil health is the continued capacity of a soil to function as a living ecosystem. There is a living ecosystem beneath everything we grow whether it is annual crops or perennials crops or forestry,” said agrologist Greg Paranich of Performance Seeds.

One acre of healthy soil contains about eight tonnes of micro-organisms and there are four primary principles for soil health:

  • Maximize continuous living roots in the soil with cover crops, biomass and forage.
  • Minimum disturbance using no-till or minimum-tillage practices.
  • Maintain maximum soil cover to keep the soil cool and prevent erosion as well as provide a more hospitable environment for the biology below the surface.
  • Maximize biodiversity with integrated pest management, pollinator plantings, rotational or managed grazing and crop selection.

Cover crops can reduce erosion, conserve water and improve infiltration as well as increase soil organic matter and structure. These crops can add nitrogen to the soil, control weeds, provide livestock feed, wildlife habitat and bee pollination and increase crop yield year over year.

“You are growing something in typical non-growth periods, between crops or in concert with crops. We want to capture any feed opportunities. We want to capture sunlight and we want to feed the soil organisms and you want to sequester carbon and capture nutrients,” Paranich said.

Grasses, brassicas, legumes and a mixture of all of those can make good cover.

New crop options are also coming to Western Canada.

Annual forges are unique because they can add significant amounts of nitrogen and work well in a cash crop rotation and also provide grazing.

Berseem clover is cold tolerant and similar to afalfa. It offers bloat-free grazing and can be mixed with other annuals for grazing.

Forage peas are annual legumes with fibrous roots and grow well in low fertility soil. They can be used as a silage or for grazing.

Spring green festololium is a hybrid cross of Italian ryegrass and meadow fescue. On trial in central Alberta, it is a cool-season grass with good palatability that could be an annual or biennial, depending on how it winters. In some regions it is a short-lived perennial.

Turnips, kale and radishes are in the brassica family. They have big tubular roots that can penetrate hardpan soil. These work well for grazing because there is a lot of leafy material on top and cattle will eat the bulbs. When the roots decay, they leave organic matter behind.

Paranich recommended cover crops in a planned rotation but it is a good idea to start small to see what works in a particular region.

“Grow enough that you can treat it like a crop, but enough that you can manage it and compare it to what you are doing already,” he said.

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