For Homework 2/20/14, only copy down what is
Name: __________________________________________________ Date: _________ ___ Per. ______ Pg. ____
highlighted in yellow onto page 23 in your binder.
Notes: Soil
1. What is Soil? Soil is a natural resource; it is made up of broken rock (mineral
fragments), air, water, humus
Parent rock: a rock formation that is the source of soil
Bed rock: the layer of rock beneath soil
2. Soil Texture- Soil particles: proportions of soil particles
Soil texture:
a. Sand-- sand is largest, <2mm to > 0.05mm
b. Silt-- medium sized, < 0.05mm to > 0.002mm
c. Clay-- smallest – invisible to unaided eye, <0.002mm
3. Soil Structure
a. Ability of water to infiltrate soil – determined by how soil particles are
arranged and if water can infiltrate (soak through) easily
Infiltration: ability of water to move through soil
4. Soil Fertility
Humus: the dark, organic material formed in soil from the decayed remains of plants
and animals
Name: __________________________________________________ Date: _________ ___ Per. ______ Pg. ____
Notes: Soil
5. Soil Horizons
O horizon – Organic litter on top of the soil (not
always there)
A horizon – TOPSOIL – much organic matter and
humus
E horizon – leaching (ELUVIATION) – nutrients
wash through and out of this area
B horizon – subsoils enriched with clay minerals,
some rocks
C horizon – parent material, weathered rock
R horizon – REGOLITH - bedrock
Leaching: the removal of
substances that can be dissolved
from rock, ore, or layers of soil
due to the passing of water
6. Soil pH-- Acid or base. 7 is neutral; most plants require a pH between 5 and 7.5
__________________________________________________________________
7. Soil Color – determined by climate and composition
8. Soil Structure
a. Ability of water to infiltrate soil – determined by how soil particles are
arranged and if water can infiltrate (soak through) easily
Name: __________________________________________________ Date: _________ ___ Per. ______ Pg. ____
Notes: Soil
9. Soil Fertility – ability of soil to hold nutrients and supply those nutrients to plants.
10.Soil Profile – Parent rock- determines type of minerals in the soil
Soil forms in layers; Parent rock is the solid bedrock from which weathered pieces of
rock first break off. Climate determines how quickly weathering occurs
 Residual soil - soil that remains above its parent rock
 Transported soil – soil that is blown or washed away from its parent rock.
11. Soil Types
a. Polar Soils– not fertile, cold with little humus
b. Temperate Soils
i. Grasslands– fertile, rich in humus
ii. Forests- clay and iron, but not as deep and rich as grasslands
iii. Prairies– dry – many plants and bushes, not as fertile as grasslands
c. Desert Soils– thin with little humus, salts, not very fertile
d. Tropical Soils– soil VERY weathered due to rains that leach nutrients out
Name: __________________________________________________ Date: _________ ___ Per. ______ Pg. ____
Notes: Soil
12. Importance of Soil
a. Nutrients– minerals and other nutrients for plants, plants provide animals
food.
b. Housing– animals!
c. Plant anchor– plants hold on to soil for support
d. Water storage– holds water for plants and animals
13. Soil Conservation
a. Contour plowing– plow ACROSS the slopes of a hill; the rows act like a
series of dams instead of a series of rivers; helps prevent erosion from
heavy rains
b. Strip Cropping– plant 2 different crops in alternating sections perpendicular
to the wind
c. Cover Crop– crops are planted between harvests to replace certain
nutrients and prevent erosion; prevent erosion by providing cover from
wind and rain.
Name: __________________________________________________ Date: _________ ___ Per. ______ Pg. ____
Notes: Soil
d. Wind Breaks Wind Breaks – hedge rows or tree breaks – perpendicular to
wind – slows wind, can’t pick up as much soil
e. Terracing – prevents erosion from heavy rains on steep hills; changes one
steep field into a series of smaller, flatter fields
f. Crop rotation - To slow nutrient depletion farmers plant different crops in
their fields that use different nutrients.
g. No-till Farming - the practice of leaving old stalks, provides cover from rain;
the cover reduces water runoff and slows soil erosion.