Download Soil and Nutrients

Where do we farm?
Soil and Nutrients
Make three observations and 1
inference
How is soil formed?
• Can come from 2 things…
– Broken down rocks (clay, silt, sand)
– Dead organic matter (humus)
• Interaction of 5 factors:
–
–
–
–
–
Rocks
Sunlight
Water
Air
Living organisms
• What determines the TYPE of soil formed?
– material it’s made from and amount of rain
Where do we farm?
Chemical Properties
Figuring out what our Robbins Park data means…
Soil and Nutrients
• 3 Primary nutrients
– N, P, K
– why do we need them?
• Limiting factor vs. poisoning
– Not enough limits growth, too much hurts plant
• Proper pH Levels
– Allow for chemical absorption of N, P, K
Nitrogen
• Growth of
leaves &
stems
• Green v
yellow
• Fungus
danger
Phosphorus
• Good root
growth
• Flower &
seed
formation
• Disease
danger
• purple
Potassium
• Strong
stems
• Ripen fruit
• Disease
danger
• Brown
edges
Where do we farm?
Chemical Properties
Let’s look at the data again…
Understanding our results
1. Finish the soil webquest
2. When done…
– Look up what levels (high, medium or
low) of N, P, K should be in good/fertile
– Look up what pH level is normal for soil
What did our data tell us about
the nutrients in our locations?
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Riverbank
Succession Field
Creepy Pond
Campsite
Field by garden
Where do we farm?
Physical properties of soil
Set up soil samples
1. Fill the jar about ½ way with soil.
2. Then fill up to the top with water.
3. Shake to mix.
4. Let it sit undisturbed.
While we’re waiting…
• Make at least 5 observations of the two
different soils
– Use ALL your senses (except taste!)
1. How are they different?
– What causes these differences?
While we’re waiting…
2.
Where are the samples from?
– Match sample A and B with Creepy Pond
or Succession Field
– How do you know?
• What evidence supports your guess?
Particle Size = Soil Texture
SAND, SILT, CLAY
Look at your sample…
• What percentage
of clay, silt, sand
do you estimate?
• How does that
help you
determine your
soil type?
What kind of soil do you have?
So what…
Why don’t plants grow well in
soil that is mostly clay?
Mostly sand?
What type of soil do plants
grow best in? Why?
What did our data tell us about the
nutrients/texture of the soil in the
different locations?
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Riverbank
Succession Field
Creepy Pond
Campsite
Field by garden
How To Vote via Texting
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Defending your choice…
• Write a paragraph(s)
1. State your overall choice
2. Using the data, defend your choice
•
Include #’s!
3. Include at least 5 vocab/scientific words
Taking care of the soil
Keeping good soil good
Soil Layers in ground
Importance of Soil
• What part
of the soil
is the
most
important
to
farmers?
Why?
Dust Bowl = desertification
Dust Bowl
Houses were shut tight, and
cloth wedged around doors and
windows, but the dust came in
so thinly that it could not be
seen in the air, and it settled like
pollen on the chairs and tables,
on the dishes."
~ John Steinbeck (from "The
Grapes of Wrath")
http://www.youtube.com/watch?v=J_LZpKSqhPQ
http://www.youtube.com/watch?v=1OdDieuD1OA
http://www.youtube.com/watch?v=vUXGBLTUD8w
Soil Erosion
• Erosion =
– movement of soil by wind or
water
• Farming speeds up
erosion
– plowing exposes soil
– precipitation washes the
soil away into
streams/rivers (runoff)
Plowing techniques
traditional plowing
contour plowing /
vegetation strips
terracing
No-till farming
No-till plowing
Advantages
• Reduces soil
erosion
– remains of first crop
holds soil in place
• Free fertilizer
• Reduces pesticide
use
Disadvantages
• not suitable for all
crops
• Soil too densely
packed
• Lower crop yields
over time
Increasing Soil
Productivity
• Chemical fertilizers - adds artificial
nutrients to aid plant growth
– Nitrogen, phosphorus, potassium
• Compost - adds natural nutrients to aid
plant growth
– decomposing material
Fertilizer Solutions
Advantages
CHEMICAL
(synthetic)
ORGANIC
(natural)
Disadvantages
Fertilizer Solutions
Advantages
SYNTHETIC Less needed
ORGANIC
Known
[nutrients]
quick
Not as harmful
Stay longer
Add humus
Disadvantages
Harmful
concentration
Easily leached
More needed
$$
Variable nutrient
am’ts
The Nitrogen Cycle
The air is
78% nitrogen,
why can’t
organisms
use this?
What role do
bacteria play
in the
nitrogen
cycle?
The Phosphorus Cycle
Takes
hundreds of
millions of
years to
complete
cycle
Sources –
Guano,
erosion of
rock, ocean
sediment