Soil is the growing medium for our food. Without it we could not survive. Soil purifies our waste. Soil is home to plants and animals. It may take up to 100 years to form one inch of topsoil. We are losing so much soil to erosion each year that the lost soil if loaded into dump trucks parked end to end would extend to the moon and back. An earthworm can work a ton of soil a year.

Mineral grains Water (between the grains in the pore spaces) Air (25%) - oxygen is essential Organic matter Bacteria-A thimble of soil can contain 2 billion bacteria 30 million fungi fragments 100,000 single cell plants and animals

Animals making burrows in the soil help bring air and water into the soil

D Humus gives the topsoil a rich brown color Leaching takes minerals carried by water to the subsoil

Mature soil profiles have 3 distinct layers (horizons) Bedrock - undisturbed rock below the soil The AO-horizon consists of highly decayed organic material referred to as humus Humus gives soil horizon-A a rich brown color.

In the A-horizon, water percolates downward and carries minerals as it goes. This is called “leaching.” Leaching carries minerals down into the lower soil horizons.

The B-Horizon is called the subsoil. This horizon is where the leached minerals from the A- horizon A end up. These leached minerals may color the subsoil. For example, the presence of iron my color the subsoil red. Horizon B-Zone of Accumulation of leached minerals

The C-horizon - the zone of weathered bedrock. Bedrock is below the C-horizon.

Sandy particles – Sand soil feels gritty (coarse-textured) when rubbed between the fingers Silt particles – Silty soil feels powdery (like flour) and does not hold together well when wet Clayey soil – Clayey soil feels smooth and sticky (like soap) when wet Loam is the best soil texture for growing things. It is a mixture that has useful amounts of clay and silt in a base of sand.

Coarse-textured soils - high sand content consist of large particles with uneven surfaces large pore spaces loose and easy to work large spaces do not retain water or nutrients. water infiltrates sandy soil and percolates (moves through it) quickly and easily sandy soils are generally dry and infertile The dryness of sandy soil contributes to a shortage of nutrients because of less vegetative growth and, therefore, less organic matter is produced.

Medium-textured soils - loams, have properties in between those of coarse and fine texture. good capacity to retain water without becoming waterlogged easy to work and form good clumping mixtures during cultivation. contain supply of nutrients (necessary for the organisms living in the soil) most suitable for the greatest variety of living organisms

Fine-textured soils - silty clay to heavy clay Heavy clays are like soft plastic when wet and are hard when dry. difficult to work Clays are often waterlogged and poorly aerated Clay soils absorb and release water (to plants) very slowly Air movement within the soil is very slow A lot of water in the spaces can mean little air is available for living organisms to carry out cellular respiration and other biochemical actions

Porosity The movement of water through the soil is controlled by certain characteristics. Porosity – The number of pores in a material compared to its volume. Usually expressed as a percentage. The movement of water through the soil is controlled by certain characteristics. Porosity – The number of pores in a material compared to its volume. Usually expressed as a percentage. Well sorted Unsorted

Porosity How much space (pores) or holes found in soil Porous soil can hold and transmit lots of water

Sorting Well sorted soils contain rounded particles similar in size not closely packed. They are the most porous. Unsorted soils which contain different sized particles and are more closely packed are less porous. Well sorted Unsorted

Soils with flattened or angular grains, such as clay soils, can pack closely together and have a low porosity.

Permeability The ability of a soil to transmit water The rate of permeability, or how fast the water moves through the soil, depends on the size of the pores and how the pores are connected – sandy soils have large well connected pores but clay soils do not. Therefore, sandy soils have a higher permeability than clay soils.

Permeable vs. Impermeable The ability of soil to allow water to flow through it Sand and gravel are permeable Clay and blacktop are impermeable

Permeability is Directly Related to Porosity POROSITY PERMEABILITY

Fertile soil contains nutrients. Macronutrients make up the bulk of the nutrients in your soil: Nitrogen (major component of protein and chlorophyll) Potassium (metabolism, roots, regulates water pressure) Phosphorus (metabolism, energy transfer, roots, flowering) Calcium, Magnesium and Sulfur Micronutrients are Manganese, Iron, Copper, Zinc, and Boron Nutrients need to be balanced and available to the plant's root Organic matter is key to helping maintain this balance