The nourishing Earth

The view of a freshly ploughed field or a meadow where a herd is grazing can give the impression of something timeless and enduring. While the changes that affect farmland are not easy to see, they are nonetheless real. The lands that provide food for Canadians are threatened by erosion from wind or water, depletion of organic matter, local or wide-scale chemical contamination, and the use of farmland for urban or industrial purposes.

Erosion—soil degradation under the effect of water or wind—is one of the main causes of the loss of farmland worldwide. The effects of this phenomenon are the most devastating on bare soil. On the Prairies, for example, 36% of cultivated land runs a high or serious risk of wind erosion in the case of bare soil, but less than 5% is exposed to this risk where the soil is subject to conservation measures. Farmers can avoid exposing the soil for excessive periods by following various practices, including no-till agriculture, green manuring and crop rotation.

Like the forests, lakes and streams, farmlands are exposed to the effects of pollutants carried by the wind. For example, acid rain has harmful effects on the soil because it reduces the availability of essential nutrients and increases the solubility of some toxic metals.

Also, the amount of farmland is shrinking because of urban sprawl. Canada's best farmland, which covers scarcely 0.5% of its land area, is concentrated in southern Ontario. By 1996, 19% of this region had been absorbed by urban growth.

Furthermore, soil contamination in general is often related to industrial wastes. The National Pollutant Release Inventory shows that approximately 35,000 tonnes of on-site pollutants were released onto the land in 2000, without counting the 164,000 tonnes disposed of by underground injection.