How does the addition of sand, clay, organic matter or water affect the bulk density and percent pore space of any soil? why can't the particle density value logically be used for the determination of bulk density for a given soil?

Explanation:

Answer 1: The bulk density also called as the apparent density or volumetric density. It is a property of the granules, powders and other solids. It is used in the reference of mineral components, foodstuff, chemical substances and any other corpuscles. The sand, organic matter and clay are the materials which can increase the bulk density of the soil. The density is directly proportional to the mass of the body.

The porosity or percentage pore space can be define as the portion of the soil volume that is occupied with the pore space. The pore spaces of the soil will reduce due to the particles added in the soil will accumulate the pore spaces of the soil.  

Answer 2: The particle density can be define as the density of the solid particles that make up the soil sample. The value of this is expressed in terms of gram per cubic centimeters. Since the pore spaces in the soil are filled with the materials which will increase the mass of the soil. Thus the accurate bulk density of the soil cannot be measured.

this is a good question! i'll do some research and come back when i have the answer!