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Sci 7- Unit 2- Topic 4-5-6

Alberta Curriculum, Science 7, Science 7 Curriculum, Plants for Food & Fibre, Unit 2- Topics 4-5-6, Science Focus 7, created by Kyle Swenson, Sturgeon School Division

kyle swenson

on 30 June 2016

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Transcript of Sci 7- Unit 2- Topic 4-5-6

Topic 4:
Meeting the Need
for Food and Fibre

Topic 5:
Sustaining the Soil

Topic 6:
Pests and Pest Control

Please read pages 132 & 133 in your textbooks.
Farming- Then & Now
Forest Industry
Global Problems
-Being able to grow food and fibre while keeping our natural sustems healthy for the LONG TERM.
Scientists, farmers and foresters are working together, developing practices that will reduce the negative effects that sometimes occur when we harvest plants for food and fibre.
Nearly all of the grassland in the prairie provinces was converted to cropland, thus destroying the natural vegetation and native plant species that had been around for a thousand years.
Please read pages 134 & 135 in your textbook.
Write out EACH crop title with ONE important fact about it.
Growing Under Glass
The yield from crops that are grown outdoors is highly dependent on the environmental conditions, climate and soil types.
Make a list of those you are able to find out about and report your findings to the class to complete the chart
There are obvious advantages, but there are also disadvantages.
higher yield
In a greenhouse all of the growinging conditions can be controlled.
Most farmers only grow one type of crop in one particular area - this is known as monoculture.
Farming Practices
To be economically sustainable, farmers need to make more money with their crops than they spend to grow their crops.
They are able to do this by using very large machinery that can cover large parcels of land as they seed and harvest their crops.
They also need to add fertilizer to the soil to increase the yield and irrigate to provide the need moisture for growth of the crop.
They are able to do this by using very large machinery that can cover large parcels of land as they seed and harvest their crops.
To be economically sustainable, farmers need to make more money with their crops than they spend to grow their crops.
They also need to add fertilizer to the soil to increase the yield and irrigate to provide the need moisture for growth of the crop.
Most farmers only grow one type of crop in one particular area - this is known as monoculture.
Please read p 140 and 141. Look at how the 9 farming activities have been meet by both early technologies and modern technologies.
Saving Soil Moisture
Irrigation is a technique that farmers use to make sure that moisture gets into the soil for crop growth.
It is often
a problem in
areas, where
the moisture
evaporated quickly.

Natural forests have many different kinds of trees, shrubs, and smaller plants.
There are many animals that make their homes in, around and under these plants.
A natural ecosystem has a higher diversity, or variety, of plants and animals than a field of wheat or a stand of trees.
Fibre Plants and the Forestry Industry
Canada has about 10% of the world's forests.
Graphs on p. 145 show the tree species harvested in Canada and the percentage value of forest products.
Harvesting Trees
Foresters decide how to cut the trees, either clear cut (removing all the trees)- or, selective harvesting (removing only selected trees).
See Figure 2.49 p. 146
Foresters attempt to improve the conditions (light, temperature, water and nutrients) within the forest.
Replanting is always done by hand.
When the trees begin to grow again,they must be removed by thinning or pruning.
Fertilizer is dropped from a helicopter to improve the level of nutrients for the young trees.
IS clear cutting trees SUSTAINABLE?
Erosion is a worldwide problem
Frequent and long-lasting droughts have resulted in desertification - a process in which desert has taken over much of the agricultural land.
Topic 4 Review p. 148
Importance of Soil
Healthy Soil is critical in natural
ecosystems and sustains our need to
grow plants for food and fibre
Without Soil, strong winds and violent storms would tear our plants from the ground. Soil is also a amazing NATURAL COMMUNITY
With a Partner discuss what you think Soil is composed of. Write down Soil's components
Soil is composed of:
dead roots
Of all the components of Soil, which is the most important? Why?
How Do Soils Develop?

Five factors determine how soils develop:
Parent material (mineral matter - rock, soil clay)
Climate (determines the kinds of plants, how fast they grow and decompose)
Vegetation (determines the amount and type of organic matter in the soil)
Landscape (helps to prevent erosion)
Time (all these process happen over long periods of time)
Read page 150 about
how soils develop
Soil: A Lively Community

Healthy soil contains soil-dwellers and decomposers. Decomposers break down plant and animal tissue, forming humus, which helps roots grow by trapping water and air.
Four main types of decomposers:
Bacteria- break down dead plants
and animal tissue
Fungi- (moulds and mushrooms)
make nutrients available to plants
Microscopic actinomycetes-a special type of bacteria
Earthworms (eat soil, grind, digest and mix it - their tunnels provide air and the mucus helps stick soil particles together)
Soil Buffet
Soil is like a buffet table for
plants it holds the water and
nutrients that plants need to
Healthy, growing plants require
6 nutrients:
Nitrogen (N)
Phosphorus (P)
Potassium (K)
Sulphur (S)
Calcium (Ca)
Magnesium (Mg)
Nitrogen- is used by plants for producing leaf growth and greener leaves.
Fertilizers are used in order to supplement nutrient supply in the soil
Typical nutrients in fertilizers:
Phosphorus- used by plants to increase fruit development and to produce a strong root system.
Potassium (potash)- is used by plants for color and size. It is also helps to strengthen the plant.
The other three nutrients;
Calcium (Ca),Sulphur (S), and Magnesium (Mg) are also important in plant growth. These nutrients usually occur in parent material in high concentrations and do not need to be added
to fertilizers
Organic vs. Chemical Fertilizer
Soil- Challenges and Solutions
Production practices have over time, sometimes damaged large areas of soil throughout the Prairie Provinces. In this topic we will look at some examples.
Salinization: Salty Soil
Page 156
What is Salinization?
The white crusty ring around a body of water is salt, which has run off the land into the water. This condition can have the same effect as a drought.
Two factors lead to increased salinization:
not enough vegetation
too much water (irrigation)
Areas of Little Vegetation
Too Much Irrigation
How can Salinization be Solved?
By replanting the areas where there is very little vegetation, so the plants can use up the water that falls before it runs off as excess
By properly managing irrigation
Using artifical drainage- although this is a costly method since power is required to use it.
Organic Matter and Erosion
Loss of organic matter is a very serious problem and can lead to soil erosion
If soil looses organic matter (which has been built up over many years) the plants may not grow very well, because of the lack of sufficient nutrients in the soil.
Ploughing and cultivating the soil too much exposes the soil surface to sunlight and higher temperatures, encouraging bacteria (decomposers) to decompose organic matter at a rapid rate and exposes it to sun and wind - which increases topsoil erosion.
Soil Erosion is when Soil is naturally removed by the action of water or wind
Saving the Soil
Soil erosion can be solved by planting a cover of vegetation on the surface to slow the flow of water runoff (giving it more time to absorb more water)
This vegetation also helps to anchor the soil particles from the wind
Zero Tillage is one way to accomplish this and it also helps control the growth of weeds
Special farming equipment is also used (seed drills), Shelterbelts (rows of trees), Modification of waterways, and Crop rotation (forage crops to add more organic matter - manure from livestock)
Seed Drills
Crop Rotation
Read Pages
158 and 159
to learn more about saving oursoil
Hydroponic Technology
Hydroponics is a technique for growing plants, without soil in a water solution. (This occurs in greenhouses in Canada)
Saving Soil in Forests
Forestry can also have an impact on soils. Removal of trees from a particular areas can lead to erosion by wind and water.
Cut areas often are littered with debris, which has been left to lower erosion (and add organic matter to the soil) and replanting programs are started after the trees have been harvested.
Begin Topic
5 Review- pg 162
A pest is any organism that is causing plants to produce less than they otherwise would.
What is a Pest?
In natural systems, organisms have parasites, predators, or competing plants that help to keep their numbers in check.
Pests which cause the most problems are:
Insects (are consumers, because they eat some or all of the plant)

Fungi (cause infections which can destroy all or part of the plant)

Weeds (are thieves, because they steal moisture, nutrients, light and space from the plant crop)
Profile of a Champion Competitor
In your notes:
Name the four reasons why Dandelions are such powerful pests!
Did you mention...
Powerful roots (long taproot)
Broad Leaves (shade other plants close by)
Super seeds (easily carried by the wind
They are very adaptable!
Please read p.166
You may be asked to identify some of the Pests that bother the Canola plant...
Introduced Species
a.k.a: exotic species
These types of pests can often become serious problems, because they may not have any natural predators, or environmental controls.
Remember that simpsons episode...
Please read p.167
Dandelions were introduced to North America, from Europe, to be used as a salad vegetable. Naturals controls were not present and , as a result, dandelions thrived and over populated the country (coast to coast).
Strange Fact...
Controlling Pests
There are various ways that pests can be controlled:
Large pests can be chased, or scared away
Smaller pests can be picked off the crop by hand
Machines (like cultivators and ploughs) can be used to uproot pesky weeds
Different crops are grown each year (crop rotation)
Regular summer fallow (controlled pests, but led to soil damage)
Chemical controls (herbicides, insecticides and fungicides)
Concerns with Chemical Controls
Long term problems were created with the extensive use of pesticides
Soil Residue
Pollutants move from level to level in the food chain. Organisms at the top of the food chain are the most adversely affected.
Some of the chemicals used as pesticides wash off the plants and leave residue in the soil and water. If the chemical is not easily decomposed they remain in the soil and can be poisonous.
Please read p.170-171:

What does a Resistant Species mean?
Looking for trouble?...

'Cause here I am!
Organic Food Production
Organic food is food that has been grown without the use of chemical fertilizers and chemical pesticides.
Manure and compost is used to add nutrients to the soil.
Pests are controlled by crop rotation, tilling, mulching, companion planting and removal of insects by hand.
Organic Farming can be more expensive, but the quality is much better, the environment is less harmed and there is a higher level of safety fro the farmer (without using chemicals)
Ask someone next to you:
If you had the choice...
would you rather buy organic food
or regular food? Why?
Biological Control
Using a pest's natural predators (enemies) to keep it's numbers under control is an effective technique, provided the species used to control the pest has its own predators to control its numbers.
1 min vid:
2 min vid:
5 min vid:
Please finish reading p.174
Unit 2- Plant for Food & Fibre
There are several ways to create small household greenhouses.
make a list of Monoculture pros and cons
here is two videos talking about the good and bad of Monoculture, pay attention, you'll be making a comparison list!
Forest fires are a natural development of forests, but foresters try to ensure that they burn in a controlled fashion (as much as possible).
click here
topic 4-5-6 wrapup
p.175 Qs- 2-4-5-7-9-11-12-13-14
Full transcript