How to Calculate Bulk Soil

Knowing how to calculate the bulk density of soil is important for many activities, such as construction, growing plants and irrigation. Bulk density tells you how much weight of soil you have per unit of volume. There is a precise formula for calculating the bulk density of your soil based on a soil sample and a few measurements. The best way to find bulk density is from an undisturbed soil sample.

1-foot PVC pipe, 2-inch diameter
Rubber mallet
Tape measure
Scale
Oven

Instructions

- 1
  Record the weight of the PVC pipe.
- 2
  Expose the soil surface so you have a bare patch of ground measuring 4 square inches.
- 3
  Pound the PVC pipe 6 inches straight down into the soil.
- 4
  Twist the PVC pipe and tip it from side to side. Remove it from the hole with all of the soil intact.
- 5
  Calculate the volume of the soil column you have removed by measuring the diameter of the PVC pipe to find the radius. Use the equation pi multiplied by the radius squared to get the surface area of the sample in inches, and then multiply that number by six, which is the depth of your sample.
- 6
  Place the PVC pipe with the soil in it in an oven set to warm for 12 hours.
- 7
  Record the dry weight of the PVC pipe and soil.
- 8
  Subtract the weight of the clean PVC pipe from the combined weight of the PVC pipe and dry soil to get the exact weight of soil.
- 9
  Divide the weight of the soil by the volume of the soil column you extracted.

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