Organic soils have much lower bulk density compared to mineral soils. In organic soils, bulk density ranges from about 0.1 g cm− 3 for Fibrists to 0.2–0.3 g cm− 3for Hemists and Saprists. In wetland mineral soils, bulk density ranges from 0.5–1.5 g cm− 3. Particle densities generally fall between 2.60 and 2.75 g/cm3 for mineral particles. Organic matter weighs much less than an equal volume of mineral solids and often has a particle density of 1.2 to 1.4 g/cm3. Typical particle densities for soils range from 2.60 to 2.75 g/cm3 for mineral particles. However, they can be as high as 3.0 g/cm3 for very dense particles and as low as 0.9 g/ cm3 for organic particles. On the other hand, organic matter generally increases the ability of the soils to hold moisture, expands the available water capacity, increases the saturated conductivity and decreases the penetration resistance of compacted soils. This is because the fine textured soils tend to organize in porous grains especially because of adequate organic matter content. This results in high pore space and low bulk density. Plant growth is affected by bulk density, Particle density and porosity as increase in bulk density or decrease in percent pore space will cause inadequate aeration and resistance to root penetration.

Properties influenced by organic matter include: soil structure; moisture holding capacity; diversity and activity of soil organisms, both those that are beneficial and harmful to crop production; and nutrient availability. On the other hand, organic matter generally increases the ability of the soils to hold moisture, expands the available water capacity, increases the saturated conductivity and decreases the penetration resistance of compacted soils. Finally, while soil compaction increases soil strength – the ability of soil to resist being moved by an applied force a compacted soil also means roots must exert greater force to penetrate the compacted layer. Addition of organic matter generally reduces density, improves aggregation and structure, and promotes biologic activity, and moderates soil temperature and hydrologic processes. Soil organic matter improves soil structure and thus increases resistance to compaction. Practices such as in-row, non-inversion sub soiling minimizes soil-surface disruption and organic-matter losses through decomposition. These practices are preferred over those that invert the soil to alleviate compaction. Organic matter increases a soil's ability to hold water, both directly and indirectly. Compaction increases bulk density and reduces total pore volume, consequently reducing available water holding capacity. Chemically, soil organic matter affects the cation exchange capacity, provides nutrients, and affects the capacity for buffering changes in soil pH. These in turn affect the fate and transport of chemicals including nutrients and pollutants. In general, organic compounds tend to possess covalent bonding. They form the building blocks for all living organisms. They are defined by diverse physical properties such as odor, solubility, density, melting point, and boiling point. Sandy, infertile soils can benefit from the addition of organic waste amendments. Annual applications of organic wastes for as long as 4 yr increased soil organic matter content, decreased soil bulk density, and increased soil water retention of a coarse-textured soil. Organic matter includes any plant or animal material that returns to the soil and goes through the decomposition process. In addition to providing nutrients and habitat to organisms living in the soil, organic matter also binds soil particles into aggregates and improves the water holding capacity of soil.

Sand, silt, and clay are made from different rocks and minerals but the other important difference between them is the size of their particles. Sand has the biggest, clay the smallest and silt is in between.The particle density is higher if large amount of heavy minerals such as magnetite; limonite and hematite are present in the soil. With increase in organic matter of the soil the particle density decreases. Typical particle densities for soils range from 2.60 to 2.75 g/cm3 for mineral particles. However, they can be as high as 3.0 g/cm3 for very dense particles and as low as 0.9 g/ cm3 for organic particles. Organic soils have much lower bulk density compared to mineral soils. In organic soils, bulk density ranges from about 0.1 g cm− 3 for Fibrists to 0.2–0.3 g cm− 3 for Hemists and Saprists. In wetland mineral soils, bulk density ranges from 0.5–1.5 g cm− 3. Clay is one of the smallest of all natural soil particles, and it tends to pack tightly together with little air space. This lack of air space and high level of compaction make clay the heaviest and densest type of soil. Cobbles: particles with a diameter larger than 75 mm; Gravel: particle sizes from 4.75 to 75 mm; Sand: particle sizes from 0.075 to 4.75 mm; Fines: particles smaller than 0.075 mm. Sandy soils contain large particles which are visible to the unaided eye, and are usually light in color. Sand feels coarse when wet or dry, and will not form a ball when squeezed in your fist. Sandy soils stay loose and allow moisture to penetrate easily, but do not retain it for long term us. Bulk density is dependent on soil organic matter, soil texture, the density of soil mineral (sand, silt, and clay) and their packing arrangement. As a rule of thumb, most rocks have a density of 2.65 g/cm3 so ideally, a silt loam soil has 50% pore space and a bulk density of 1.33 g/cm3. On the other hand, organic matter generally increases the ability of the soils to hold moisture, expands the available water capacity, increases the saturated conductivity and decreases the penetration resistance of compacted soils. Organic matter from both grass and peat reduced bulk density and increased moisture retention. While organic matter from grass increased soil shear strength from 19.17 to 24.44 kN m−2, that from peat reduced it from 15.47 to 11.90 kN m−2. Organic matter causes soil to clump and form soil aggregates, which improves soil structure. With better soil structure, permeability improves, in turn improving the soil's ability to take up and hold water.