Chapter 12. 2 SoilChapter 12.4 Soil as a Resource

• What is parent material? MATERIAL FROM WHICH SOIL IS FORMED

• What is residual soil? A soil whose PARENT material is the bedrock beneath the soil. The Bluegrass region of Kentucky is an example of a residual soil.

• What is transported soil? Soils formed elsewhere and deposited, by winds, rivers, and glaciers, in other locations. An example would be soils in the Midwest and New England are transported.

• What is Humus? Fertile, rich, soil formed from ORGANIC materials such as decaying plants and animals. Nitrogen is abundant in humus. Found in the uppermost layer of the A horizon.

Soil Profile and Horizons

O Horizon: top organic layer of soil, mademostly of leaf matter & humusA Horizon: topsoil; gray to black organic-rich,clay-poor soil with plant material; plant rootsgrow hereB Horizon: subsoil; red or brown color fromiron oxides; made of clay & minerals washeddown from above; some roots grow here [clay]C Horizon: slightly weathered parent material & rock fragments [pebbles]

D Horizon: un-weathered rock [bedrock

Layer beneath soil is bedrock

Soil Types

• Arctic Soil – Areas with cold climates, rock materials weather slowly, shallow soil profile

• Temperate Grassland- Areas with mild/temperate climates, enough rain to grow grass well but not a lot of trees. Good soil for farming.

Soil Types, cont.

• Temperate forest soil- Areas with temperate/mild climates with heavy tree growth. Good for farming.

• Tropical grassland- Areas with dry/tropical climate, warm and dry all year with wet and dry seasons. Rock materials weather quickly, soil profiles are deep

Soil Types, Cont.

• Tropical Forest Soils- areas with humid (moist/wet) tropical climate, warm and rainy all year. Rock materials weather quickly and soil profiles are deep.

• Desert Soils- areas with little or no rainfall. Limited vegetation which means more wind erosion. Sandy soil

Soil as a Resource

• Soil fertility: the ability of a soil to grow plants. • Soil depletion: when the soil is over farmed and gradually

becomes lacking or depleted in the necessary nutrients for growing crops.

• What are ways that soil depletion can be reversed? • Add fertilizers, rotate crops, don’t use a field for a time so that

it can naturally replenish its nutrients, or add fertilizer. Fertilizers are not the best way to improve soil due to the ecological hazards that fertilizers can create.

Ways to reduce soil erosion

• Windbreaks – plant trees along the edges of fields. This stops/breaks the wind and reduces the impact of the wind on the field’s erosion.

Contour Farming

Contour Farming: Prevents water from flowing rapidly downhill and carrying soil with it. Instead of planting in rows up and down, the farmer plants in rows that follow the contour of the land.

Terraces

• Terraces: Flatten slopes into terraces to prevent run off.

Strip Cropping

• Strip Cropping: Alternating a row of crops that leaves bare ground with a row that covers the ground. An example would be corn in one row (bare ground beneath the stalks) with alfalfa, which covers the ground.