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: – 0.05 mm CLAY: < 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
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 – x ‐ 227 Silt 0.05 – x Clay < x x 10 6
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 h/1406/outlines/chapter%202/chap02.html
s/dna_packing_website/DNA_chemical_struct ure.jpg DNA has a negative charge because of the sugar backbone
Electronegativity in Clay -OH group can create electronegativity pH can be very important
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.