Texturing Guides By Dr. John Galbraith, Virginia Tech Clay % by Ribbon

1. Texturing Guides By Dr. John Galbraith, Virginia Tech Clay % by Ribbon Start with a big ball of soil, twice as big as a golf ball. Toss out all dry clods, rocks, and roots. Squeeze it into a horizontal ribbon, until it bends or breaks Multiply the number of inches times a fudge factor to get clay% Fudge factors: Iron and Al oxides are clay but not sticky or strong, so they need the biggest factor BC horizons and E horizons need a short factor Sticky, plastic clays need a moderate factor Nonsticky, nonplastic clays need a medium factor Dark, nonsandy A horizons need a medium factor All others need a short factor Often, the short factor = 10, medium = 15, and biggest = 20 but that must be determined for each region. I use 10 on the Ridge and Valley and Coastal Plain and Floodplain soils and all A horizons, 15 on orange or beige Piedmont soils, and 20 on shrink-swell clay subsoils, reddish Piedmont subsoils and Triassic Basin subsoils. On brick red subsoils (10R) where red Iron stains your hands after a quick rinse with water, I use a factor of 40.

2. The Ribbon Test This ribbon bent at just about 1 inch in length

3. This ribbon did not bend or break at all

4. The Sand % Test Rub some soil in palm, then wash it like panning for gold

5. Gently wash the silt and clay and tilt your hand slowly. Use the hand lens to estimate % sand, then add a fudge Factor of 5 or 10% for the very fine sand lost in washing

6. Very fine sands and loamy very fine sands, or other sandy textures with high organic matter content, and any finer textures, will hold into a ball when dropped. Top photo. Coarser sands and loamy sands will crack open or break as in bottom photo.

7. If you can make very thin, sharp, tiny ribbons on your thumb, it has > 40% clay

8. If you push really hard and can make a continuous, smooth, shiny surface with no skip marks, it has at least 35% clay. Top has > 35%, bottom has less.

9. Reading the Texture Triangle The example texture is a Clay Loam with 35% clay, and 30% sand. That leaves 35% silt (we can’t estimate it, but can calculate it)

10. Other Mineral Texture Guides • If you push into the ball gently, and it feels powdery, it is a silt or silt loam • If you can see sand grains almost all touching each other, it has about 50% sand • If they touch other sand grains on all sides, it has 75% or more sand • Sandy Textures: Sands or loamy sands. • Loamy or Clayey Textures (grouped together): Any mineral texture except sands and loamy sands.

12. Organic Content and Modifiers • Organic Soil Material: An O horizon with > 18% OC, or if the clay content is less than 60%, the OC > (clay %/10) +12. Light brown to black in color, organic matter smell, very low bulk density (spongy). • Mucky peat: Some dark brown to black liquid flows out when a ball is squeezed tightly, or up to ½ of the sample flows out. • Muck: The most highly decomposed organic soil material. Must be black (value 2.5 or 2), and feels greasy after five rubs. Bulk density is very low (~ 1/3 to 1/2 of mineral subsoil clod of similar size). When saturated and squeezed, a dark liquid and ½ the mass flows out between fingers, or the whole mass flows out if no liquid flows. Leaves a black stain on your hands. Evident organic smell. • Mucky modified textures: Must have between 5 and 12% organic carbon. Very dark (value 3 or less), and feels slick or greasy when rubbed once or twice. When squeezed, no liquid and < 2/3 of the sample flows out between fingers. Sand grains are easily felt in sandy textures. May be light in density (~1/2 to 2/3 of mineral subsoil clod of similar size). Very slight staining on hand and faint organic smell.