Soil Profile, Classification and Physical Properties Soils & Fertilizers for Master Gardeners In-service Training June 9, 2008 Amy Shober UF/IFAS Gulf Coast REC

What is a Soil? A natural body comprised of solids, liquid and gas that occur on the land surface.

Photo credits: USDA-NRCS The Soil Profile A horizon – Surface layer w/ organic matter E horizon – Leached horizon between the A and B horizons B horizon – Zone of accumulation of material transported from the A and B horizons C horizon – Parent material

Florida State Soil Photo Credits: Mary Collins, UF-IFAS Myakka fine sand

Soil Taxonomy Order Suborder Great Group Subgroup Family Series

Twelve Soil Orders Alfisols – Soils with subsurface clay accumulation; medium to high amount of bases (Ca, Mg, K, and Na) Andisols – Soils formed in volcanic ash Aridisols – Carbonate soils of arid environments with subsurface development Entisols – Soils with little or no horizon development

Twelve Soil Orders Histosols – Organic soils Inceptisols – Soils with weakly developed subsurface horizons Gelisols – Soils with permafrost within 2 meters of the surface Mollisols – Grassland soils with high base status

Twelve Soil Orders Oxisols – Intensely weather (sub)tropical soils Spodosols – Acidic forest soils with subsurface accumulation of metals/organic matter Vertisols – Clayey soils that shrink/swell Ultisols – Strongly leached soils with subsurface zone of clay accumulation and <35% base saturation

Composition of Soils

Mineral Particle Size Classifications Sand 0.05 – 2.0 mm Clay < mm Silt mm

Surface Area Sand ParticleClay Particles Area of cube = l x w x 6 27 cubes with 6 sides 1 cube with 6 sides

Soil Texture & Textural Class Texture is the proportion of sand, silt and clay Florida soils –Sand –Loamy land –Sandy loam Photo credits: USDA-NRCS

Soil Structure Soil structure is the way soil particles are held together Called aggregates or peds Florida soils have weak or no structure Figure Credit: University Corporation for Atmospheric Research

Granular Structure Photo Credit: USDA-NRCS

Blocky Structure Photo Credit: USDA-NRCS

Platy Structure Photo Credit: USDA-NRCS

Prismatic Structure Photo Credit: USDA-NRCS

Columnar Structure Photo Credit: USDA-NRCS

Soil Color

Photo Credit: James Bonczek, UF-IFAS Hue: dominant spectral color; Related to the wavelength of light. Value: related to total amount of light reflected. Chroma: measure of the strength of spectral color.

Soil Density Particle Density Mass solid particles in a unit volume Depends on particle type (mineral vs. organic) Average = 2.65 g/cm 3 Bulk Density Mass soil in a unit volume Depends on pore space Bulk density range – Sand = 1.2–1.8 g/cm 3 –Clay = g/cm 3