Understanding Concepts: Read pages 210 & 211. Then answer the following questions:
1. Why is soil important? Without soil, plants cannot grow.
2. What features distinguish each soil layer from the others?
Soil layers are distinguished by the size of the rock particles in the layers, and the amount of soil along with the humus content.
3. Describe how soil is formed.
Soil is formed by the breaking down of rocks mixed with decaying plant and animal matter.
4. Soil can be divided into layers or horizons (see figure 1 on page 210). Using the below provided chart, state the functions of these layers. See Textbook page 210 for the answers
4.9 Soil and Plant Growth (pg. 214-215)
Making Connections: Read pages 214 & 215. Then answer the following questions:
1. Why is the humus content in soil important?
Humus gives soil the necessary nutrients and minerals required for plant growth.
2. Why are the spaces between soil particles so important?
The spaces between particles are important because they provide the necessary air for microorganisms to survive. It is the action of the microorganisms which decomposes organic.
3. Why does clay alone make a poor soil for growing most plants?
Clay particles are so close together that water and air cannot penetrate it. Therefore, less air will be available for soil organisms.
4.10 Farming & the Soil (pg. 216-217)
Making Connections: Read pages 216 & 217. Then answer the following questions:
1. Explain how the use of heavy machinery on farmland causes problems with the soil.
Heavy machinery can compact the soil by pressing the soil particles closer together. compressed soil does not have sufficient spaces between particles for either water or air, both of which are necessary for soil improvement and plant growth.
2. Name one problem related to modern farming methods and a possible solution.
Possible problems include ploughing, which breaks up soil, making it more susceptible to wind and water erosion; and chemicals, which can be carried into nearby waterways through water erosion.
3. What are the advantages of zero tillage?
Zero tillage reduces or eliminates the vulnerability of the land erosion.
4.11 Erosion: Carving the Landscape (pg. 218-219)
Understanding Concepts: Read pages 218 & 219. Then answer the following questions:
1) Why is there more soil in southern Ontario than in northern Ontario?
The soil in southern Ontario was pushed there ahead of several periods of glaciation. During these periods, the soil in northern Ontario was scraped from the surface of the rock that makes up the Canadian Shield.
2) What erosive force created most of the lakes in Ontario?
The force of gravity, acting on the huge masses of ice that were glaciers, caused depressions in the Earth�s crust that formed lakes.
3) Using a series of diagrams, explain how a river changes from being young and straight to old and winding.
Over time, rivers cut soil away from the outside of curves and deposit it on the inside of other curves. This results in the curves getting larger and rounder, and the rivers becoming slower and more winding.
4) Glaciers slow down the formation of soil on the one hand, yet speed it up on the other. Explain how this is true.
Extreme cold conditions slow down the formation of soil by slowing the activity of organisms that decompose plant and animal material. Glaciers speed up soil formation by scraping the rock surface and breaking off smaller pieces in a process that would otherwise take millions of years to weather away.
5) There have been five ice ages in the last 2 million years. Do you think we have seen the last of the ice ages? Why or why not?
Answers may vary. Yes (based on all the current evidence of global warming). No (based on the cycles tend to repeat themselves)
