Soil is composed of particles of varying sizes, and its texture refers to the composition of these particles, such as sand, silt, clay-sized particles, and organic matter.
Soil color provides valuable information about the organic matter content, the parent material from which the soil originates, the degree of soil weathering, and its drainage characteristics. Soils with high iron content exhibit deep orange-brown to yellowish-brown shades, while those rich in organic matter appear dark brown or black.
Soil structure pertains to the arrangement of sand, silt, and clay particles in clusters. Sand particles are the largest, while clay particles are the smallest, and most soils are a combination of these three components. The relative proportions of sand, silt, and clay determine the overall texture of the soil. Additionally, the presence of organic matter (from decaying plants and animals) and soil organisms, such as earthworms and bacteria, also influence soil structure.
The arrangement of soil particles significantly affects plant growth by influencing the movement of water, air, and nutrients to plants. Sandy soils typically lack structure but provide good drainage, whereas soils with higher clay content have a stronger structure but may have reduced drainage capabilities.
Soil porosity refers to the empty spaces within the soil that are not occupied by mineral or organic matter but are instead filled with gases or water. Poor-quality soils have limited visible pores, cracks, or holes, and the management practices applied to the soil can impact its porosity.
Soil density is related to the mineral and organic composition of the soil and its structure. On the other hand, soil consistence describes the ease with which an individual soil particle, known as a ped, can be crushed by fingers. This characteristic varies with the soil's moisture content.
Aggregate stability indicates the soil's ability to form and maintain larger, more durable aggregates. Soils rich in organic matter tend to have stronger and more stable aggregates that resist compaction, whereas soils with less organic matter may have weaker aggregates. Improving soil aggregate stability offers several benefits for an agroecosystem, including a reduced risk of soil compaction and erosion.
Soil physical characteristics
