impacts > Agriculture >
Crop production impacts
In this section, you will find potential benefits and drawbacks for crop production in Manitoba due to
Higher CO2 levels
Crop species vary in their response to carbon dioxide. C3 plants, such as wheat, rice and soybeans, respond readily to increases in carbon dioxide, and could produce greater yields. C4 plants, such as corn and many pasture and forage species, are less responsive to higher levels of carbon dioxide. (1)
Recent open-air field trials in Illinois, however, raise questions about how much yields might increase. The trials involving five major food crops grown under carbon dioxide levels projected for the future resulted in a much lower carbon dioxide fertilization effect on yield for C3 crops than earlier expected, and possibly little or no stimulation for C4 crops. (2)
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Higher temperatures
Growing season
Predicted changes in Manitoba’s temperatures could result in a longer growing season due to more frost-free days and earlier seeding times for most crops. For every 1oC increase in average temperature, the growing season could lengthen by 10 days on the Canadian Prairies. This could mean a wider range of cropping options. (3)
The increased temperatures in the winter could reduce the amount of winterkill of fall-seeded crops.
As well, crop-producing areas may expand northward. It is estimated that for each 1oC increase in mean annual temperature the vegetation zones may move northward by 200–300 km. (4) However, this doesn’t necessarily mean it would make economic or ecological sense to expand agricultural production northwards.
Insects and pathogens
The exact impacts of climate change on insects and pathogens is somewhat uncertain—some changes may be favourable to insects and pathogens while others may be negative. Most evidence, however, indicates an overall increase in the number of outbreaks of a wider variety of insects and pathogens. (5)
Weeds
Higher temperatures may encourage new weeds to expand into higher latitudes. (6)
Soil Quality
Warmer temperatures increase soil microbial activity, speeding the natural breakdown of organic matter and other processes that affect fertility. (7) But a longer growing season with more vegetative mass produced may offset the increased breakdown of organic matter.
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Changing precipitation
Water Availability
Of the total rainfall expected, more will fall in intense events, so the length of dry periods between rains will likely increase. Together with warmer temperatures (causing more evapotranspiration), the result will likely be increased drought frequency and severity.
The rise in springtime precipitation, however, could have some positive impacts on groundwater recharge and soil moisture.
Overall, the availability of water for agricultural production is likely to become a major issue. (8)
Soil Erosion
More soil erosion is possible with greater intensity of rainfall and increased risk of flooding. The expected increases in drought will also increase the risk of soil erosion by wind during critical periods.
