Soil texture | Soil Science

Terms: soil texture, sand, silt, clay, loam
Soil that’s ideal for plant growth is about 50% solids and 50% air, aka pore space. By volume, the solids are typically about 45% minerals and 5% organic matter, and the pore space should be around 25% air and water.
Soil texture refers to the particle size of the mineral component - the more important sizes are sand, silt and clay.
• Sand particles are between 2.0 and 0.05 millimeters in diameter. They are visible to the naked eye and feel gritty when rubbed together. Sand particles do not stick together and are not sticky to the touch.
• Silt particles are smaller, ranging from 0.05 to 0.002 millimeters. They are not visible without a microscope and feel smooth and flour-like when dry. When wet, they do not feel sticky but have a smooth texture.
• Clay particles are less than 0.002 millimeters in diameter. When wet, clay feels sticky, and when dry, it forms hard clods. Clay particles are flatter in shape, so they have a really high surface area and thus a large impact on soil even in small amounts.
Based on the proportion of the particle sizes, soil can be classified into soil textural classes (refer to the "soil textural triangle"). Loam is not a particle size, rather it's a set of soil textural classes that have enough of each particle size to still have the benefits of each.
Do not attempt to change soil texture - it's better to focus on improving structure (next video).
Video index: docs.google.co...