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AGROECOSYSTEMS

AGROECOSYSTEMS. Agroecosystem. 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. Agricultural Land-Use.

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AGROECOSYSTEMS

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  1. AGROECOSYSTEMS

  2. Agroecosystem 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

  3. Agricultural Land-Use • 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.

  4. Changing face of agriculture 2001 vs 1996

  5. Source: Statistics Canada

  6. Animal Units per km² of Farmland on Very Large Livestock Operations LEGEND 5-15 16-25 26-35 36-50 50-100 >100 No large operations Non-agricultural/no data

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

  8. Area of Land Irrigated (hectares) LEGEND 0 1-100 101-1000 1001-5000 5001-20000 20000-115000 No data

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

  10. Canada's Most Important Agricultural Products Grains, oilseeds and meats

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

  12. Economic Importance 1.8 million people employed in agri-food industry

  13. Where do exports go? Total export value: $6.0 billion in 2001 $5.2 billion in 2002 $4.2 billion in 2003 1/2 of Alberta's production is exported

  14. SOILS OF ALBERTA

  15. Components of Soils

  16. http://www.physicalgeography.net

  17. CHERNOZEM SOIL PROFILE

  18. DARK BROWN CHERNOZEMIC SOIL

  19. Type of Mineral Particle Size Range Sand  2.0 - 0.06 mm  Silt  0.06 - 0.002 mm Clay less than 0.002 mm

  20. Soil Texture Triangle

  21. Field Capacity Maximum water content before gravity drainage begins Wilting Point Water content below which water is held so tightly to the soil that plants cannot take it up

  22. Soil texture vs. porosity, field capacity and wilting point

  23. The Effects of Human Activities on Agricultural Lands • ORGANIC MATTER • 15-30% reduction from original level • Generally stable today (improved tillage, • crop residues, manure and fertilizers)

  24. WIND EROSION

  25. 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

  26. Oldeman, Hakkeling & Sombroek (1990)

  27. Alleviating Soil Erosion PLOWING STYLE Contour Farming Especially important on steeply-sloping terrain, and in wet areas Terracing TIMING Field tilled in spring

  28. Terracing - Peru

  29. ZERO TILLAGE Advantages EROSION CONTROL MOISTURE CONSERVATION REDUCED LABOUR LESS FUEL USED EQUIPMENT SAVINGS Disadvantages CROP IN COMPETITION WITH WEEDS MORE HERBICIDES USED FROST DAMAGE?

  30. 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

  31. 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

  32. 4. SALINIZATION

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

  34. DESERTIFICATION VULNERABILITY

  35. CHEMICAL CONTAMINATION 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

  36. 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)

  37. Intensive Livestock Operations Benefit Very profitable – competitive on global scale Downside Health, environmental and nuisance effects NIMBY

  38. Sign in Walkerton, Ontario

  39. FEEDLOT "ALLEY" North of Lethbridge 500,000 cattle 200,000 hogs 600,000 poultry

  40. BSE Bovine spongiform encephalopathy An infectious degenerative brain disease occurring in cattle

  41. CJD

  42. BSE 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

  43. sCJD • 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

  44. vCJD • 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

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