A community of living organisms, together with the physical resources that sustain them, that are managed for the purposes of producing food, fibre and other agricultural products

• Agriculture now covers more of Earth’s surface than forests.
38% of planet’s land surface = agriculture
26% pasture/rangeland
12% cropland
•
Intensive monocultures completely displace natural ecosystems and have a heavy impact on the land.

Source: Statistics Canada

LEGEND
5-15
16-25
26-35
36-50
50-100
>100
No large operations
Non-agricultural/no data

•
Requires large capital investment
•
Mechanized
•
Chemical inputs (fertilizers, pesticides and herbicides)
•
Monocultural
•
Huge farms
•
Irrigation and/or drainage (some areas)
•
Little summerfallow

LEGEND
0
1-100
101-1000
1001-5000
5001-20000
20000-115000
No data

Satellite Image of
Lethbridge and
Surrounding Area
False colour &
True colour

http://www1.agric.gov.ab.ca

1.8 million people employed in agri-food industry

Total export value:
$6.0 billion in 2001
$5.2 billion in 2002
$4.2 billion in 2003

http://www.physicalgeography.net

Sand
2.0 - 0.06 mm
Silt
Clay
0.06 - 0.002 mm less than 0.002 mm

Maximum water content before gravity drainage begins
Water content below which water is held so tightly to the soil that plants cannot take it up

Ranges of porosities, field capacities, and permanent wilting points for soils of various textures.
(from Dunne and
Leopold, 1978)

1. ORGANIC MATTER
•
15-30% reduction from original level
• Generally stable today (improved tillage, crop residues, manure and fertilizers)

2. SOIL EROSION
• Most severe soil degradation problem
(due to wind and water in absence of natural vegetation, and appropriate tillage )
•
Topsoil contains most nutrients and organic matter
• Wind erosion problematic everywhere, but especially on Prairies
• Water erosion most severe in Maritimes,
British Columbia and Ontario
• Water erosion affects water quality

Oldeman, Hakkeling & Sombroek (1990)

Contour Farming
Terracing
Field tilled in spring
Especially important on steeply-sloping terrain, and in wet areas

EROSION CONTROL
MOISTURE CONSERVATION
REDUCED LABOUR
LESS FUEL USED
EQUIPMENT SAVINGS
CROP IN COMPETITION WITH WEEDS
MORE HERBICIDES USED
FROST DAMAGE?

STRIP FARMING
Plant another crop between rows
Covers ground with vegetation
Prevents erosion
Water infiltrates instead of running off
POLYVARIETAL CULTIVATION
Entire field is not exposed at once
ADDING ORGANIC MATTER
Manure
Plowing crop residues
Green manure

3. SOIL STRUCTURE
•
Vulnerability to structural degradation
(i) low organic matter
(ii) wet environment
(iii) fine texture
•
Soil Compaction
Often due to heavy machinery
Affects rooting
Not a big problem on the Prairies

Visible salinity in 12 sets air photos (Alberta) http://www1.agric.gov.ab.ca

1. HEAVY METAL CONTAMINATION
(eg. cadmium, lead and zinc)
FROM WHERE?
a) Atmospheric deposition (industry+natural) b) Fertilizers, manure and sewage sludge
2. ACID PRECIPITATION
•Leads to nutrient deficiency

3. GROUNDWATER CONTAMINATION
High nitrate levels (due to fertilizers)
Fecal coliform bacteria (manure & septic tanks)
Phosphorus levels can increase (eutrophication)
Pesticides are often found in water, but are generally found in concentrations considered acceptable (Canadian Water Quality
Guidelines)

Benefit
Very profitable
– competitive on global scale
Downside
Health, environmental and nuisance effects

An infectious degenerative brain disease occurring in cattle

One of many transmissible spongiform encephalopathies (or TSEs)
•
First recognized in Britain in 1986
•
Caused by a prion, a protein normally believed to be involved in neuronal plasticity (serves memory function)
•
In a case of BSE, an insoluble form of a prion accumulates in the brain
•
BSE is fatal

CJD is a brain-wasting disease causing anxiety, disorientation, memory loss, numbness and death within a year
•
Affects 1 person in 1 million
Its cause is uncertain
1. Random genetic mutation?
2. Meat consumption? (controversial)
Tends to affect people over 55

• vCJD is the new variant form of CJD, which is believed to be caused by eating infected beef
•
145 deaths in the UK so far

40000
35000
30000
25000
20000
15000
10000
5000
0
(# of Canadian cases = 2)
(# of Canadian deaths = 0)

(World Organization for Animal Health)
•
No meat and bone meal (MBM) imported from the
UK or other BSE countries since 1978
•
Ban on ruminant MBM to ruminants since 1997
•
Compulsory notification and investigation of all ‘downers’ for past 7 years.
•
An education and awareness program in place for years

•A few animals likely could have become infected before the feed ban (vast majority culled, slaughtered or died long ago)
•A limited number of live cattle imported from the
UK in the 1980s . Did any have BSE?
•One to a few of these animals may have entered the animal feed chain (further spread impossible after 1997 and infectivity was low then)
•BSE incubation time is 6 years (important for analyzing the Canadian case

•Manure & commercial fertilizers are key to economic viability/soil nutrient maintenance
•Most N, P and K assimilated by plants or absorbed by soil: remainder affects surface runoff or groundwater
•Pesticide contamination also problematic –
Alberta levels generally within CWQG
•Pesticides now specialized & less persistent

•
Feedlots required to meet domestic + offshore demand
•Major market for Canadian grains
•‘Canadian Bacon’ well-known: economical and high quality
Problem: volume of manure produced

•Excellent slow-release fertilizer
•Source of organic matter
•Potential biogas source
•Causes groundwater contamination
•Leaching of nitrates
•Bacteria and parasites
2003 Manure Conference (Lethbridge)
•Air quality: nuisance effect for some
•Health effects may include headaches and nausea (psychosomatic?)

Biogas reservoir bag for electric power generation at facility in Valle del Cauca, Colombia (near Cali) http://www.ias.unu.edu/proceedings/icibs/ic-mfa/chara/paper.htm

•Feedlot runoff collected in slurries or ‘lagoons’
•Manure stored in impervious facilities and allowed to decompose (6 months +)
•Applied to land when crop nutrient intake rapid and runoff least likely
•Manure is trucked away and deposited on area fields to prevent local contamination

•
Increases range of crops that can be grown
•Dramatically increases yield
•
Highly consumptive use of water
•
Evapotranspiration
•Causes salinization in prone areas (

ET&WT)
•
Reservoir construction required
•Alters fish and wildlife habitat
•Floods cultural/historical sites
•Provides recreation opportunities

of Burdett, Alberta
Source: Zimmatic

Source: Zimmatic

•
Replacement of indigenous plants with crops on a massive scale
• < 1% of tallgrass prairie remains
• 18% of shortgrass prairie
• 24% of mixedgrass prairie
• 25% of aspen parkland
•Drying of biodiverse wetlands
•Use of insecticides and herbicides

Most of North America’s wetlands have been drained, filled, and converted for agricultural use.

•Tallgrass prairie
•Mixedgrass prairie
•Fescue prairie and foothills fescue
•Forested rangelands
•Wetlands
•Coulee complexes

Done badly, it can ruin soils, and cause erosion and desertification.
Done responsibly, it can sustain grasslands, and allow wildlife use.

•
Hundreds of plant species
•
Grazing animals
•Bison, elk, deer, antelope plentiful
•
Predator and scavenger populations high
•Grizzly bear, prairie wolf, coyote, swift fox, eagles as well as magpies and crows (latter two are still plentiful)