SOIL FERTILITY

Which soil profile is likely to be more fertile?AB

Soil ProfilesSoil Profile (B)MORE FERTILEBlack in color.Rich in organic matter in the form of humus. Less leaching and mineral rich soil.Found in grasslands which are semi-arid.

Soil Profile (A) LESS FERTILEGray in color, ashy appearance.Severely leached and highly acidic.South of the tundra regions of the Northern hemisphere. Typically found in the Boreal forest.

Soil Fertility and PrecipitationHeavily leached soilsBlack prairie soilBrown prairie soilLightly leached soil

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Why are Tundra soils infertile?Pg: 92

Tundra soils are infertile because:The subsoil is permanently frozen (permafrost).Plant roots cannot get water or grow downward.

In the summer surface soil thaws, the soil beneath stays frozen, hence water cannot move downward.

Surface soil is now:Water loggedColdFree of airTherefore, material cannot decay and form humus, so there is no organic nutrients for vegetation.

Soil ErosionSoil erosion: The process by which soil is worn away by wind, water, heat, cold, glaciers, loss of plants, etc.

Forests and Soil Erosion

Forests prevent soil erosion through the use of their roots (roots hold the soil together).If the forest was removed, the soil would not have protection from wind, rain, or warm temps. Wind would blow the soil away. Rain would flood the soil. Warm temps. would heat up and dry out the soil.

Forests also add decaying material to the soil, so if the forests were removed, the soil would have no nutrients.

WatershedsWatershed: the area of land where all of the water drains to the same place.

Watersheds

Forests and WatershedsForests maintain watersheds by: Protecting and enhancing water supply.Help filtrate the water.Preventing the soil from drying out. Reduce flooding.Add nutrients.

Latitude and Altitude

Depletion of the Ozone Layer