Presentation on theme: "1 Introduction to Soils The most important natural resource around the earth!"— Presentation transcript:
1 Introduction to Soils The most important natural resource around the earth!
2 What is soil? Defined as: Mineral & Organic material that supports plant growth on the earth’s surface Mixture of particles of rock, organic materials, living forms, air, water
3 What soil resources help in supporting life? Oxygen: needed for adequate root growth Temperature: soil absorbs heat from the sun – loses heat to atmosphere (plant growth and seed germination) Water: plant growth Carbon: organic matter Nutrients: minerals
4 Briefly explain the process of soil origin. All soil originated as rocks. Powerful forces act on the rocks to break them down into smaller fragments. Water penetrates the cracks in the rock and when it freezes the water acts as a wedge to split the rock.
5 Soil origin cont. Rivers, glaciers, landslides and avalanches cause rock particles to grind against each other wearing them down. Chemicals mix with water to further break the rocks down. Plants began to grow in the weathered rocks and as they die, they add organic matter to the soil which attracts soil micro- organisms.
6 Soil origin cont. When this happens, the soil is capable of supporting plant life and can then truly be called soil.
7 What does the term weathering mean? Weathering is the processes that occur to break down rock into soil. This process includes water freezing, thawing, landslides, wind and chemical action.
8 What is parent material? Rock material that has undergone some weathering and change, but not enough to be called true soil, as it is not capable of sustaining plant life.
9 List the 5 factors responsible for soil development. 1.Parent material 2.Climate 3.Variation in the earth’s surface (topography) 4.Plant & animal life 5.Time
10 Components of Soil Mineral Matter: about 45% of soil (partially decomposed rock material (sand, silt, clay) Organic Matter: about 5% of soil (partially decomposed plant & animal matter) Air: about 25% of soil (constant fluctuation as soil is dry and wet) Water: about 25% of soil
11 Water in the soil Infiltration: process of water soaking into the soil Percolation: water movement downward Permeable: quality soil allows for both infiltration and percolation – then it is said to be permeable
12 Living Organisms in the soil Forms of life: –Earthworms –Insects –Bacteria –Fungi –Other organisms
13 Bacteria & Fungi Jobs Break down organic matter and release nutrients
14 Earthworm & other soil organism jobs Improve soil tilth –Ease at which soil can be worked –Create openings in soil as they tunnel –Enhances drainage and improves air exchange
15 Plants use soil A.Anchorage – roots B.Water – absorbed through roots C.Oxygen – all living organisms need oxygen -plants release oxygen during photosynthesis and consume oxygen during respiration -good soil aeration needed for below ground plant parts to get oxygen
16 Plants use soil cont. D. Nutrients – of the 16 essential nutrients for plant growth – 13 are obtained from the soil -root hairs absorb the nutrients dissolved in soil water
17 Soil uses in agriculture Cropland Grazing land Forest Water structures Agriculture depends on soil to grow food, fiber, and ornamental plants.
18 Nonagricultural uses of soil Recreation: playgrounds, sports fields, jogging paths, golf courses, parks, campgrounds Foundations: buildings have to have solid base Waste Disposal Building materials