Erosion and Sediment Control
Touch It, Feel It: A Hands-on Soil Texture Workshop
Soil texture is derived from the percentage of three soil separates (e.g., sand, silt, and clay) and cannot be easily changed by the addition of soil amendments. Understanding the benefits and limitations of soil texture will improve your ability to: 1) establish healthy vegetation; 2) predict and reduce the potential for soil erosion; and 3) select appropriate Best Management Practices (BMPs) for the soil conditions.
There are generally twelve (12) recognized textural classes that are found in most U.S. States and, in order from coarse-grained to fine-grained, includes sand, loamy sand, sandy loam, loam, silt loam, silt, sandy clay loam, clay loam, silty clay loam, sandy clay, silty clay, and clay.
Soil texture influences soil properties including but not limited to 1) infiltration rate; 2) moisture retention; 3) availability of air; and 4) erodibility of the soil. To determine the soil textural class, typically one conducts laboratory testing by a mechanical soil analysis to determine the percentage of sand, silt, and clay soil separates. However, that takes time and if you want a quicker and reasonably accurate technique for Erosion and Sediment Control Professionals in the field, this workshop will teach you how to collect the sample and apply simple hand texturing methods in the field including ribboning and making a wire to determine the textural class of the site soils.
Understanding the textural class of a soil helps an Erosion and Sedimentation Control Professional select appropriate land use techniques to reduce soil loss during construction and this information will support the proper selection of BMP to further reduce erosion and prevent sedimentation outside of a work area.
Soil texture can greatly influence the amount of infiltration or run-off on a site. The soil's ability to infiltrate helps reduce the amount run-off, which can lead to less erosive forces on the soil surface due to the time of concentration of the flow. The availability of water in the soil profile offers numerous benefits including a thriving and productive microbial population that converts nutrients into a readily assimilated form for uptake by the plant roots. The ability of the soil to provide a suitable growth media, retain moisture, and resist erosion is, in large part, a function of its texture.
The workshop will include a 20-30-minute presentation on soil texture including benefits and restrictions that relate to managing soil on a construction site. The remaining portion of the workshop will include hands-on field testing such as ribboning and attempting to make a wire for prepared soil samples of the various textural classes. Although a popular field test 40+ years ago was to put soil in your mouth to determine the general amounts of the three soil separates, we will not be eating soil to determine its texture.