Sticking To It GK-12 Workshop October 5 th 2011. PART I: Soil Texture What is soil texture How do you measure it? What is your soil like at your school.

Presentation on theme: "Sticking To It GK-12 Workshop October 5 th 2011. PART I: Soil Texture What is soil texture How do you measure it? What is your soil like at your school."— Presentation transcript:

Sticking To It GK-12 Workshop October 5 th 2011

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?

Soil texture SAND: 0.05 – 2.00 mm SILT: 0.002 – 0.05 mm CLAY: < 0.002 mm Source: Brady, N & Weil R

Example: 15% sand 15% clay 70% silt

Texture by feel method Preparation:  Place approximately 2 tsp. soil in palm  Add water slowly and Knead soil to break down all chunks  Consistency like moist putty Source: Dr. Del Mokma

Texture by feel method 1.soil will not cohere into a ball, falls apart: sand 2.Soil forms a ball, but will not form a ribbon: loamy sand Source: Dr. Del Mokma

(c) Gritty, noncohesive appearance and short ribbon sandy loam Silt loam (smooth) Clay (smooth and long ribbon) Source: Brady, N & Weil R

Web soil survey http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm

Sedimentation method Layer D: organic materials Layer C: Clay Layer B: Silt Layer A: Sand

Stokes’ law Velocity V(cm/s)= K D 2 K = 11,241 cm -1 sec -1 Sand: D = 1 mm= 0.1 cm V = 11,241 x (0.1) 2 = 112.4 cm/sec clay: D = 0.002 mm =0.0002 cm V = 11,241 x (0.0002) 2 = 0.00045 cm/sec George Gabriel Stokes

Sedimentation method Layer D: organic materials Layer C: Clay (2 days-2weeks) Layer B: Silt (2 hours) Layer A: Sand (1-2mins)

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 2mm1mm

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 10 6 454 Clay < 0.002 90 x 10 9 8 x 10 6

http://www.theodora.com/wfb/photos/greece/greece_photos_15.html 16g clay

Surface area= 4πa 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 balls

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?

Part II: Chemistry Using the BeST plots for chemistry – Ions, valence, electronegativity

What is an ion? Cation and Anion Examples from the BeSt plots

Valence Electrons Draw Valance for: Nitrate, Ammonium, N 2, Phosphate, Calcium ion, etc.

Electronegativity The ability of an atom in a molecule to attract shared electrons to itself http://iws.collin.edu/biopage/faculty/mcculloc h/1406/outlines/chapter%202/chap02.html

http://www.mit.edu/~kardar/teaching/project s/dna_packing_website/DNA_chemical_struct ure.jpg DNA has a negative charge because of the sugar backbone

http://bioweb.wku.edu/courses/ biol115/wyatt/biochem/lipid/P- lipid.gif http://www.yellowtang.org/images/lipid_bilay er_c_la_784.jpg

http://www.biosci.ohio- state.edu/~prg/protein1.gif http://biotech.matcmadiso n.edu/resources/proteins/l abManual/images/amino_0 00.gif Amino Acids have charge- which determines how proteins fold

- - - - - - - - - - - - - - - - ClaySand - - - - - - - - - - - - - - - - - - - Soil has a net negative charge Clay has positive and negative charge and high surface area

http://www.northeastern.edu/chem/faculty_and_rese arch/faculty/geoffrey_davies1/ Lignin Humic Acids Decomposing organic matter has electronegative properties Gives soil it’s negative charge

Electronegativity in Clay -OH group can create electronegativity pH can be very important

http://courses.soil.ncsu.edu/ssc051/chapters/i mages/fig2-2_4.gif Soi Mg 2+ Al 3+

- - - - - - - - - - - - - - - - ClaySand - - - - - - - - - - - - - - - - - - - - NH 4 + H+H+ NO 3 -

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 nitrified – Nitrogen is usually low (N 2 )

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.

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