Sticking To It - PowerPoint Presentation

Slide1

Sticking To It

GK-12 Workshop

October 5

th

2011Slide2

PART I: Soil Texture

What is soil texture

How do you measure it?

What is your soil like at your school using a NRCS map?

What is your soil texture if you use the sedimentation method?Slide3

Soil texture

SAND: 0.05 – 2.00 mm

SILT: 0.002 – 0.05 mm

CLAY: < 0.002 mm

Source: Brady, N & Weil RSlide4

Example:

15% sand

15% clay

70% siltSlide5

Texture by feel method

Preparation:

Place approximately

2 tsp. soil in palm

Add water slowly

and Knead soil to

break down all chunksConsistency like moist

putty

Source: Dr. Del MokmaSlide6

Texture by feel method

soil will not cohere into a ball, falls apart:

sand

Soil forms a ball, but will not form a ribbon:

loamy sand

Source: Dr. Del

MokmaSlide7

(c)

Gritty,

noncohesive

appearance and short ribbon

sandy loam

Silt loam (smooth)

Clay (smooth and long ribbon)

Source: Brady, N & Weil RSlide8
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Web soil survey

http://websoilsurvey.nrcs.usda.gov/app/HomePage.htmSlide10
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Sedimentation method

Layer D: organic materials

Layer C: Clay

Layer B: Silt

Layer A: SandSlide17

Stokes’ law

Velocity V(cm/s)= K D

2

K = 11,241 cm

-1

sec

-1Sand: D = 1 mm= 0.1 cmV = 11,241 x (0.1)2= 112.4 cm/secclay: D = 0.002 mm =0.0002 cm

V = 11,241 x (0.0002)2= 0.00045 cm/sec

George Gabriel StokesSlide18

Sedimentation method

Layer D: organic materials

Layer C: Clay (

2

days-2weeks

)

Layer B: Silt (

2 hours

)

Layer A: Sand (

1-2mins

)Slide19

Each face is 4 mm

2

6 faces x 4 mm

2

= 24 mm

2

Each face is 1 mm

2

6 faces x 1mm

2

x 8= 48 mm

2

2mm

1mmSlide20

Diameter (mm) Particles /g Surface Area cm

2

/g

Sand 2.0 –0.05 90-722 x 10

3

11 ‐ 227

Silt 0.05 – 0.002 5.8 x 106 454

Clay < 0.002 90 x 109 8 x 106Slide21

http://www.theodora.com/wfb/photos/greece/greece_photos_15.html

16g claySlide22

Surface area=

4π

a

2

Volume=

Ball =

mm, volume =

Marbles

= a= mm , volume = mm3 x Number of marbles = mm3

Large ball= a= mm, surface area= mm2

Marbles= mm, volume = mm2 x marbles = mm2

Calculating surface area and

volume:

Measuring in class with ballsSlide23

Class discussion: Pore sizes

Different particles sizes have different spaces in between.

What do you think the pore spaces between clay and sand compare?

How is this important for air and water

?

How would pure clay and sand relate to plant growth? Why?Slide24

Part II: Chemistry

Using the

BeST

plots for chemistry

Ions, valence, electronegativitySlide25

What is an ion?

Cation

and Anion

Examples from the

BeSt

plotsSlide26

Valence Electrons

Draw Valance for:

Nitrate, Ammonium, N

2

, Phosphate,

Calcium ion, etc.Slide27

Electronegativity

The ability of an atom in a molecule to attract shared electrons to itself

http://iws.collin.edu/biopage/faculty/mcculloch/1406/outlines/chapter%202/chap02.htmlSlide28

http://www.mit.edu/~kardar/teaching/projects/dna_packing_website/DNA_chemical_structure.jpg

DNA has a negative charge

because of the

s

ugar backboneSlide29

http://bioweb.wku.edu/courses/biol115/wyatt/biochem/lipid/P-lipid.gif

http://www.yellowtang.org/images/lipid_bilayer_c_la_784.jpgSlide30

http://www.biosci.ohio-state.edu/~prg/protein1.gif

http://biotech.matcmadison.edu/resources/proteins/labManual/images/amino_000.gif

Amino Acids have charge- which determines how proteins foldSlide31

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Clay

Sand

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Soil has a net negative

charge

Clay

has positive and negative

charge and high surface

areaSlide32

http://www.northeastern.edu/chem/faculty_and_research/faculty/geoffrey_davies1/

Lignin

Humic

Acids

Decomposing organic matter

has electronegative

properties

Gives soil it’s negative

charge Slide33

Electronegativity in Clay

-OH group can create electronegativity

pH can be very importantSlide34

http://courses.soil.ncsu.edu/ssc051/chapters/images/fig2-2_4.gif

Soi

Mg

2+

Al

3+Slide35

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Clay

Sand

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NH

4

+

H

+

NO

3

-Slide36

Important for Nitrogen Cycle

Cool facts: DNA

and lipids can be found in soil.

DNA can be bound to clays!

Nitrogen Cycle

Nitrate easily lost

Ammonium can be adsorbed to soil OR nitrifiedNitrogen is usually low (N2)Slide37

Conclusion

Soils in the

BeSt

plots have different kinds of soil

The texture could be important for explaining plant growth

Texture has certain physical and chemical properties which then determines how much water and nutrients are being held.