SOIL The Origin of Life
Objectives • Explain why agriculture and all life is dependant on the soil. • Explain the difference between organic and inorganic soil.
Soil • The mineral and organic surface of the earth capable of supporting upland plants.
Food Chain • Constant cycle • Begins and ends with the soil • What is the example in the book?
Four Ingredients of Soil • Minerals • Air • Water • Humus
Minerals • Do not come from living organisms • Very small particles • Have chemical and physical properties that can be formed into rocks.
Pores • Formed between the mineral particles • Filled with water or air
Humus • Organic matter – produced by living animals and plants • Decomposed plants and animals
Organic soils • Contain lots of organic matter. • The result of the build up of plant materials that grew in the soil, died and decayed. • Hundreds of years to make fertile soil.
Organic Soil • Very rich in nutrients • Very productive soils.
Inorganic Soils • Originates from the breaking down of rock • Usually a result of weather • Extremely slow - thousands of years. http://www.worldofstock.com/closeups/NTR1852.php
Inorganic soils • Weather ???
Inorganic Soils weather Break down • Wind against rocks • Rain, sleet, and snow against the rocks remove particles. • Process of wetting and drying dissolves minerals • Freezing and thawing opens cracks for more water to enter
Inorganic Soils • Glaciers - slow moving ice • Glaciers crushed the rock creating soil. • Moraine – land mass built up by a glacier
Erosion • Definition?
Water-deposited soil • Alluvial soil – soil that has been moved and deposited by moving water. • soil that has been picked up and washed down stream and deposited.
Water-deposited soil Flood plains – areas along a river or stream that flood when the river exceeds its banks Soil is deposited in these areas as the water recedes back within it’s banks.
Water deposited soils • Deltas – Soil deposited at the mouth of a river • As the water slows the soil falls out • The soil is built up over a period of time.. • The Mississippi delta is on great example
Mississippi Delta • Where did this soil come from???
Water deposited Soil • Can a lake be filled by soil from a river or stream??? • Is this good soil??
Wind Deposited soil • Wind creates soil by wearing away the stone. • Called eolian soils • Large particles are called sand and form dunes • Fine particles are called silt and clay and are
Soil Texture • The size of the individual soil particles
Sand • Largest particle of soil • Feels gritty and coarse
Silt • Smaller than sand • Will feel smoother than sand but not smooth
Clay • Smallest particle of soil • Smooth, like flour
Texture • Relative size….
Loam Soil • Ideal for crops • Less than 52 % sand, 28 – 50 % silt and 7-27 % clay • Clay and silt prevent water from moving through the soil. • Sand lets too much water go through the soil • This mixture is just right for holding water in the soil.
Soil PH • The pH is a measure of how acidic the soil is. • The pH affects nutrient availability
The pH • Blue berries prefer a lower ph 4-7 • Asparagus prefers 6-8
the pH scale • To make the soil more acidic we add sulfur • To make the soil more alkaline we add lime
Soil Horizons • Soil forms in parallel layers called Horizons • The horizons are formed from different materials giving them a different color and texture. • If a pit is dug you can see the various Horizons of soil
Soil Ecosystem • Ecosystem – all of the plants and animals that life in an area • All are necessary for the “balance of nature”
Rhizosphere • – the area around the roots of a plant – where the plant receives water and nutrient • Many microorganisms live here. • Carbon Cycle – plants die and return nutrients back to the soil.
Microorganisms • Symbiotic relationship – bacteria helps the plants use nitrogen • Plants that host the rhizobia for nitrogen are called Legumes. • Bacteria enters the root hairs and form nodules on the root, then transform nitrogen into a useful form.
Microorganisms • Fungi – plantlike organisms that contain no chlorophyll • Fungi help breakdown and decay plant material
Microorganism • Protozoa – feed on bacteria and help keep the balance
microorganisms • Nematodes – smooth round bodied worms • Eat decayed matter, other microorganisms and plant roots • The last group causes major concerns for farmers.
Soil Essential for life - All of our food sources depend on the soil. We need to take care of the soil…