Soil texture is defined as the proportion of what particles in the soil?

Soil texture is defined specifically by the relative proportions of sand, silt, and clay particles present in the soil. Each of these particles has different sizes and characteristics, which significantly influence the soil's properties such as drainage, nutrient retention, aeration, and the ability to support plant growth.

Sand is the largest of the soil particles, providing good drainage but low nutrient retention. Silt is smaller than sand and has a higher capacity for retaining moisture and nutrients, while clay is the smallest particle, known for its ability to hold water and nutrients but can also create drainage issues if in excess. Understanding these proportions is crucial for forest workers in assessing soil health and making informed decisions about planting and soil management.

In contrast, the other options contain various combinations of soil and non-soil constituents that do not accurately describe soil texture. For example, gravel and compost do not fit into the particle size classification scheme used for defining soil texture. Therefore, the definition of soil texture remains grounded in the proportions of sand, silt, and clay, making this the correct response.