Unit

BULK DENSITY OF SOIL

1. Describe the concept and importance of soil density.

2. Determine soil density.

3. Explain how to alter soil density.

4. Describe the effect of soil density on erosion, water holding capacity and flooding.

Objectives

Texture

Bulk density

Consistence

Particle density

Structure

Terms

What is bulk density?

Describe the concept and importance of soil density.

- Density is the mass of an object divided by the volume.

- Bulk density is a measurement of how tightly soil particles are pressed together.

- Texture, the relative proportion of soil separates in a soil, affects the

density, as different separates have different masses and have corresponding pore space.

Bulk density

- the arrangement of soil particles into aggregates or peds, also determines density because

various soil arrangements will compact more easily than others.

Structure

- of the soil is the mass per unit volume of soil particles

excluding the pore space.

Particle Density

the soil’s response to pressure at various moisture levels, can be

described as hardness, friability, stickiness, and plasticity.

-The soil consistence,

How can you determine soil density?

Determine soil density.

- When removed from the earth’s crust the soil contains air and water that will affect the mass readings and do not constitute soil density.

- Soil density is the mass of the soil particles divided by

volume.

- Density is usually expressed in grams per cubic centimeter.

- The soil needs to be dried in order to find the true density.

How can you change soil density?

Explain how to alter soil density.

- The working of the subsoil by a subsoil tillage system can decrease the density of the soil by encouraging more pore space per volume.

- Soil density is affected by tillage and non-tillage systems.

B. Some seedbeds and fields have too little soil density so rolling the field or working the soil with a finisher may provide better seedbed density.

- At construction sites it is important to have a compacted subsoil so settling will not occur once the building is completed.

What effect does soil density have on various soil characteristics?

Describe the effect of soil density on erosion, water

holding capacity, and flooding.

A. With higher the soil density the amount of pore space decreases, thus decreasing the water holding capacity of the soil. This decrease in water holding capacity is especially significant in the larger pore spaces that are readily available to hold water which plants can utilize.

IV. Soil density affects soil characteristics.

-can also be affected by density, as water will not infiltrate the soil as readily -will stay in contact with the topsoil for a longer period of time.

Erosion

-Flooding will result from excessive runoff and decreased infiltration in wet years. -Puddling can result from localized compaction, as is the case in tractor tire ruts.

Flooding

Bulk density =oven - dry weight in grams

volume of cylinder in cubic centimeters

Bulk Density Equation.