Do Now: Over the course of this week we have done many labs on soils. Imagine a world without soil. Would life be possible? Explain your answer in complete sentences.

Aim: How are soil layers classified?

E. Soil Layers Formation

1. O horizon uppermost, primarily organic material (including wastes, decomposing bodies, live organisms) –Dark crumbly material resulting from decomposition of org. material forms humus

2. A horizon AKA topsoil Made up of weathered rock & some organic material that migrated from O horizon Important in plant growth Zone of leaching

3. B horizon Receives all the minerals that are leached out of A horizon as well as organic material that are washed down from topsoil Zone of illuviation

4. C horizon Bottommost soil layer Composed of larger pieces of rock that have not undergone much weathering

5. R horizon The bedrock Lies below all other soil layers

E. Soil Layers Formation

A profile of soil showing topsoil, sand, clay pocket, and sandy gravel.

II. Soil problems A. Soil needs to be fertile –Fertility tells you the soil’s ability to provide essential nutrients (N, P, K) to plants

1. Arable soil allows the pores between clumps to store water –Soil needs to aggregate (form clumps) to have pores –Loamy soil is evenly composed of all three types of soil (clay, silt, sand) Considered the best for plants

B. Farming affect on fertility 1. Repeated plowing tends to break down soil aggregates leaving it unfertile (“plow pan”, “hard pan”)

2. Monoculture Repeated growing of only one crop leads to lack of genetic variation of that crop –more susceptible to disease or pests –leaches soil of needed nutrients for growth Solution: crop rotation- different crops are planted in the area in each growing season

3. Soil Conservation Methods

Solutions: mixture of monoculture crops planted in strips on a farm in central Wisconsin

Solution: Organic Farming

Solution: Sustainable Organic Agriculture

Homework Read pages Answer question 3 on pg 315