F ROM B EDROCK TO S OIL Section 10-3 pg

W HAT IS S OIL ?

A NSWER Soil- is a loose mixture of small mineral fragments organic material water Air that can support the growth of vegetation

V OCAB : Parent Rock Rock formation that is the source of mineral fragments Bedrock Layer of rock beneath the soil So bedrock is the parent rock The soil above it is call residual soil

Transported soil Soil that is blown or washed away from its parent rock Can be done by wind, water, glaciers moving, weather

S OIL T EXTURE Is the soil quality that is based on the proportions of soil particles Can be small to big (2mm) This affects the soil’s consistency This is the soil’s ability to be worked/farmed

Large proportions-clay is difficult to farm in Soil texture influences the infiltration (ability of water to move through soil) Water needs to get to plants But don’t want soil to be saturated in water

S OIL S TRUCTURE Water and air movement through soil is influenced by soil structure This is the arrangement of soil particles How spread out they are Clumpy-won’t let air or H2O through

S OIL F ERTILITY Is the soil’s ability to hold nutrients and to supply nutrients to a plant Nutrients can come from parent rock Nutrients can come from Humus Organic material formed in soil from the decayed remains of plants and animals Broken down by decomposers

S OIL HORIZONS Soil ends up in a series of layers = Horizons Top layer- is humus—rich layer Called top soil Good top soil is necessary for farming Sediment middle Parent rock—bed rock bottom

S OIL P H Soil can be acidic or basic Scale 0-14, 7 neutral below 7 = acidic above 7 = basic This influences how nutrients dissolve in the soil

Basic- nutrients don’t dissolve-hurts plants Acidic- plants can’t take in other certain nutrients Right pH decides what plant can grow there

T ROPICAL R AIN F OREST Air is humid, large amounts of rain, warm temp. Crops grown yr round Decay is at a high rate- so nutrients in soil

Soil Nutrients low- heavy rain takes it to deeper part Top soil is thin Plants grow—take a huge toll on nutrients

D ESERT Not a lot of rain, Very low rates of chemical weathering soil is created slower Less able to support plants

Groundwater- comes from surround areas-comes to surface-then evaporates can’t get all nutrients in time High is salts- toxic to plant

T EMPERATE F OREST /G RASSLANDS Much of USA is this Lots of weathering Get enough rain— chemical weathering to happen Change in temp -get frost action

Get thick fertile soil Most productive soil Midwestern = Breadbasket

A RCTIC Little rain— chemical weathering is low and slow Soil forms slowly Thin and don’t support life Low temp.— low decomposition rate Low number of nutrients

T HE E ND