# 5.9: Activity 1 - Bulk Density and Porosity of Soil Cores

Name: ______________________________

Section: _____________________________

Student ID#:__________________________

Step 1: Three soil cores are displayed in metal cylinders. The volume of the cylinders and the mass of dry soil in each core are given. Using these data, determine the bulk density of each soil sample. Assume the particle density of the soil in all cores is 2.65 g/cm3. Calculate the % porosity for each sample. Record the data and include the soil texture and soil condition (disturbed, compacted, or undisturbed) of each soil sample. Core volume V = πr2h.

Core Description of soil texture and structural condition Mass dry soil (g) Bulk Density (g/cm3) Porosite (%)
1
2
3
Core volume (cm3)

Step 2: Now that you have practiced calculating bulk density and porosity, you will do the same calculations for your prepared soil samples collected in the first week of lab.

Show your detailed Bulk density and porosity calculations:

Bulk Density = ___________ g/cm3

Porosity = ___________ %

Bulk Density Questions

1. Explain how the addition of organic matter to these soils would affect their bulk density.
2. Which of these soils will usually have the higher bulk density, the sandy soil or clayey soil? Why?
3. How does your bulk density value from your ring sample compare with those given in Table 1?
4. Calculate the bulk density of a soil with a porosity of ___30%___ by using the porosity formula and assuming the particle density of this soil is 2.65 g/cm3.