Corn & The Environment

Historical Perspectives

Major changes have occurred in Canadian, and, particularly, Ontario corn production over the last 40 years. Despite a long history of production by native Canadians, and the introduction of hybrid corn during the 1930s and early 1940s to replace the open-pollinated varieties which had been grown previously, corn was a relatively minor crop in Canada, grown primarily in the warmest areas of south-western Ontario, prior to 1960. With the development of better-yielding and earlier-maturing hybrids, corn acreage expanded rapidly during the 1960s and 1970s. (See Grain Corn Acres (Hectares), 1908-1995 and Canadian Grain Corn Acres (Hectares), 1908-1995).

The introduction in the early 1960s of atrazine, a herbicide which controlled most weeds in corn fields but which could not be used on other major Ontario crops, also encouraged this rapid growth in corn acreage.

Expansion in the sixties and seventies
As a result of the above, corn changed from being a minor, regional crop, to the dominant feed grain and cash crop of Ontario by the mid 1970s. By 1980, over 30% of Ontario's 3.5 million hectares of cultivated farm land was seeded annually to corn. On many farms, both cash-crop and livestock (beef, hog and poultry), corn became the only crop, grown as a monoculture (no other crops in the rotation). Expansion in corn acreage occurred in other provinces, especially Quebec, at about the same time.

By the late 1970s, it was apparent that monoculture corn was causing several agronomic and environmental problems: Soils seeded to corn year after year, especially with the intensive tillage methods which were dominant at that time (fall moldboard plowing, plus several secondary tillage operations in the springtime, with few crop residues left on the soil surface), were becoming poorer in soil structure and more prone to soil erosion. Corn yields on many farms were stagnant despite the release and usage of a steady stream of newer hybrids of increasing yield potential. The production of only one crop meant excessive instability in farm income. Corn rootworm, an insect pest in monoculture corn, became prevalent across Ontario during the 1970s and early 1980s, and this necessitated the application of soil insecticides where corn was grown for two years or more in succession. Certain weed species developed genetic resistance to atrazine, and atrazine was being detected in some streams and rivers.

As a result of the above - and a perception that, because of its association with modern agricultural technology, corn was a cause of other real or perceived farm environmental problems - corn was labelled by some as being "bad for the environment" - with some justification.

Major changes in the eighties

Fortunately, much has changed since the late 1970s. Corn is now grown in monoculture by only a few farmers. Soil-building crop rotations are the usual practice. Corn acreage has declined by about 20 percent in Ontario, with other crops such as soybeans and winter wheat (the latter often inter-seeded with red clover) becoming more important as cash crops. Intensive tillage practices are being replaced by conservation tillage (no moldboard plowing, fewer secondary tillage operations) and even no tillage. Both leave crop residues to protect the soil surface after harvest. The use of atrazine has declined substantially in Ontario, with this herbicide being replaced by newer products which are broken down by soil organisms more quickly. (See Corn and pesticides.) Crop rotations add to the weed control and soil-fertility-supplying options available to farmers.

However, corn remains a dominant Ontario and Canadian crop. Because of its importance to Canadian, North American, and global society, it is important that questions be asked and answered concerning the sustainability of corn production.

Can corn continue to be a major agricultural crop in Ontario for the next millennium as it has been for much of the present one? What are the effects of newer corn production practices on the natural environment? Is corn production sustainable? Can its sustainability be improved?

These and related questions are the focus of other sections in Corn and the Environment. The discussion features the technology which is expected to dominate Canadian corn production during the final years of the 1990s and the decade to follow, rather than cultural practices which are more prevalent in the past.