Threats to Soil

Environmental or Natural Factors: Temperature Extremes - too hot or too cold! Extremes - too hot or too cold! Affects humus accumulation (low temps.= slow the decay of organic matter). Affects humus accumulation (low temps.= slow the decay of organic matter). Too cold for any vegetation to grow = nothing to die, no humus. Ex. Tundra and Polar ice caps. Too cold for any vegetation to grow = nothing to die, no humus. Ex. Tundra and Polar ice caps. Too hot = drought, with wind = dust storms or wind erosion. Ex. deserts Too hot = drought, with wind = dust storms or wind erosion. Ex. deserts Too cold = frozen ground, slow growth or short growing season. Again no humus! Ex. Tundra & Polar Ice Cap. Too cold = frozen ground, slow growth or short growing season. Again no humus! Ex. Tundra & Polar Ice Cap.

Threats to Soil Environmental or Natural Factors: Precipitation Extremes = too wet or too dry! affects mineral content (rain causes minerals to be eluviated or leached.) Washing away the soil or ground. (Erosion)…nutrients (leaching) Too dry = less vegetation growth = less accumulation of humus ex. Deserts Too wet = muddy, soaked soil = plants less able to obtain nutrients

Human – Threats to Soil pg Poor Soil Management Overusing the land …planting the same crop ALL the time. Determine what land is BEST suited for and using it for that reason. Ex. Don’t build on agricultural land. (urban expansion!) Ex. Don’t grow grasses where land BEST suited for grapes. Ex. Using chemical fertilizers and pesticides. Ex. Leaving soil / land fallow. (NOT planting)

Threats to Soil pg URBAN EXPANSION: Q.Is this the BEST use of this land? Q.What does this land seem MORE suitable for? Q.What other OPTIONS do they have?

Threats to Soil - Desertification the spread of desert-like soil conditions in a semi-arid environment. Turning productive soil into unproductive, dry, desert-like soil! Occurs in hotter, drier areas and is accelerated by overgrazing, deforestation, leaving land fallow

Threats to Soil Flooding Flooding Overgrazing Overgrazing Deforestation Deforestation Erosion

Reducing Soil Erosion Pg. 142 Strip cropping Alternating strips of open-growing crops and close-growing crops. the close-growing crops act as a buffer or barrier to wind erosion. As well, the close-growing plants and roots prevent or hamper soil erosion (running water)

Reducing Soil Erosion Pg Strip cropping

Reducing Soil Erosion Roots prevent water erosion. Soak up water preventing flooding Increasing humus content = plants get ploughed back into the soil returning any nutrients left in the plant. Cover cropping Planting close- growing crop when NOT planting a harvest crop. Ground cover = shade = prevents soil from drying out, Close growing plants prevent wind erosion

Reducing Soil Erosion - Cover cropping

Reducing Soil Erosion Contour ploughing Respects the natural shape of the land. Crops planted perpendicular to slope of land and water run-off. Prevents soil erosion due to run-off.

Reducing Soil Erosion Terracing Constructing steps or shelves in the sides of hills or sloping land to reduce water run-off and retain moisture.