Physical Properties of Soil

Soil Samples USESoil TypeWhy? Garden Livestock Pen Roadway Drainage Area Building Foundation Match the soil samples in the boxes with the best use: Samples: Sand, Potting Soil, Gravel, Clay

Structure of Matter All material objects are composed of Atoms. Different kinds of atoms are called elements. Elements combine to form compounds. Compounds make up the world around us!

The ATOM Parts of an ATOM: Nucleus Protons Neutrons Electrons Protons and neutrons move within the nucleus. Electrons are in constant motion around the nucleus forming a cloud

Physical Properties of Soil Soil consists of four parts: mineral matter, organic matter, water, and air The mineral and organic matter of a soil store nutrients required by crops. The relative amounts of mineral and organic matter determine the physical properties of soil.

Mineral (Inorganic) material Broken down by weathering, particles of various size are produced. Scientists classify the soil particles into three categories. Clay, Silt, and Sand

Clay The smallest particles Important in holding nutrients. Clays feel sticky and are hard to squeeze. Will hold more water than coarse- textured soils but may not be ideal

Silt The 2 nd largest particles Silts are medium-sized and feel soft and silky. Medium-textured loam soils are most suitable for plant growth

Sand The largest particles. Sands are loosely held together and will feel gritty Coarse soils, like sands and gravels, have relatively large pores but very few.

Soils Vary in their proportions of clay, silt, and sand. Soil scientists classify different soil types by their proportions of sand, silt, and clay.

Testing Soil Texture – percent of sand, silt, and clay Porosity - The amount, size and arrangement of pores Permeability – rate at which water moves through soil Water Holding Capacity (WHC) - the ability of a soils micropores to hold water for plant use

Properties of Soil SandSiltClay Porosity mostly large pores small pores predominate Permeabilityrapidlow to moderateslow Water holding capacity limitedmediumvery large TexturegrittySilky smoothSoft sticky

Other Properties Soil Structure - The arrangement of soil aggregates. Soil Color - is a study of various chemical processes acting on soil. Bulk Density - of a soil is the weight per unit volume of soil, & reflects the porosity of a soil.