From Rocks To Soil Soil Soil is a

From Rocks To Soil

Soil • Soil is a mixture of weathered rock, organic matter, minerals, water, and air. • Soil is made by climate, types of rock, type of vegetation, and time.

What are you made of? All soil is made of sediment. Clay, silt, and sand are particles of sediment. Decaying plants and animals are called humus. Important nutrients such as carbon, nitrogen, and phosphorous come from organic matter. • Space between soil particles may be filled with air or water. • •

All soil is layered by density and size of the particles

Layers of soil

What’s in the soil?

Draw This…

The different layers of soil • Horizon O & A (Top Soil) – Organic material and humus, very little rock. • Horizon B (Middle Soil) – Less humus and some minerals, more dense due to clay. • Horizon C (Bottom Soil) – Weather rocks and denser particles with some pieces of rock.

Different soil in Different Places Climate: temperature & precipitation The type of rock being weathered and eroded The type of vegetation in the area Soil erosion: soil on steep slopes does not develop well, due to it being washed away • Time • •

Climate and soil • The rate at which the water cycle will happen can highly affect the type of soils present and the type of minerals created.

Soil color • Soils of the humid tropics are generally red or yellow because of the oxidation of iron or aluminum, respectively. • In the temperate grasslands, large additions of humus cause soils to be black. • The heavy leaching of iron causes forest soils to be gray. • Organic matter colors the soil black. • The combination of iron oxides and organic content gives many soil types a brown color.

Colors of soil

Soil p. H • p. H is how acidic or basic a material can be. Water is neutral. • The scale is from 0 to 14. • Anything 7 or below is an acid. • Anything 7 or above is a base.

Why is p. H important? • In order for plants to obtain nutrients, the nutrients must be carried into them by being dissolved into the ground water that the plants absorb through their roots.

Soil p. H & Plants • If a soil has too much acid, the nutrients in the soil will be dissolved too quickly, and leeched away as the water drains. • If a soil is too base (alkaline) then the nutrients will not dissolve quickly enough.

General p. H for plants