T6+Slides

T6+Slides - Effects of Compaction on Porosity 5 10 15 20 25...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Topic #6 Soil Density and Porosity Understand the concepts and relationships among “bulk density”, “particle density” and “porosity” Importance of soil density Management of soil density Bulk Density Particle Density Includes pores and solids Includes only solids
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Measuring Bulk Density Collect soil core Weigh dry soil Dry in oven 105 o C Porosity (%) = (1 - D b /D P ) 100 D b /D P = Fraction of solids D P ~ 2.65 g/cm 3 What is the porosity of a soil which has a D b = 1.8 g/cm 3 and a D p = 2.65 g/cm 3 ? Porosity = (1 - 1.8/2.65) × 100 = (1 – 0.68) × 100 = 32% Macropores vs Micropores Number of pores fine fine fine coarse coarse coarse Clay texture Loam texture Sandy texture Pore Size Distribution versus Texture Sand Loam Clay Volume of micropores T o tal P ro sity Volume of macropores V l u m e f p r s a c Low High Porosity versus Soil Texture Crumb Structure
Background image of page 2
3 Biopores
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Effects of Compaction on Porosity 5 10 15 20 25 30 35 40 Macropores Micropores Non-tilled Tilled 33% 17% 35% 25% Non-tilled Total = 58% Tilled Total = 52% Why does bulk density general increase with increasing soil depth? Effects of Forest Harvest on Bulk Density 1. Less organic matter 2. Less root and animal mixing 3. Compaction by overlying soil Traffic Pans Depth of tillage Low D b High D b 4 Low bulk density High bulk density D b > 1.5 to 1.9 g/cm 3 restrict root growth Soil Crusting from Raindrop Impact Soil cover (plants and residues) can greatly reduce crust formation Surface crusts impede gas and water movement Traffic pans impede root growth and gas/water movement Minimizing compaction by increasing surface area Breaking up subsurface traffic pans & hardpan layers...
View Full Document

This note was uploaded on 01/27/2011 for the course SSO 10 taught by Professor Randydahlgren during the Fall '10 term at UC Davis.

Page1 / 4

T6+Slides - Effects of Compaction on Porosity 5 10 15 20 25...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online