Ms. Peterson
Transcript of Ms. Peterson
Ms. Peterson
What is soil??
Is it dirt?
Is it mud?
Soil is the top few inches of earth’s crust and the stuff that plant roots grow in.
There are four major soil ingredients
Minerals
Organic Matter
Water
Air
Minerals and organic matter are the solid particles in the soil
Water and air fill the spaces between the particles
Soil also contains living organisms-some large, some small
Inorganic elements are compounds that naturally occur.
Minerals in soil comes from rocks and other materials that have weathered
Sand
Silt
Clay
Other Minerals
Sand is the largest-size mineral particle in soil
Sand does not hold water well
Soils that are high in sand are not fertile because water moves through it quickly and washes the nutrients away
Silt particles are smaller than sand
Silt particles fill spaces between sand particles
Sometimes deposited by water when land is flooded or washed into the oceans where streams empty
The Mississippi River Delta is an example of a land mass that was developed by silt settling from the flood water of the Mississippi River.
Can you think of another famous river delta?
Clay is the smallest particle in soil
Clay fills the spaces between sand and silt particles
It gives soil the ability to hold water
Soils that are high in clay are slow to dry out after a rainfall
Clay holds minerals that plants need for growth
Other minerals in soil are important in plant growth
They are often added in fertilizer to give plants more nutrients.
The major minerals are:
Calcium
Phosphorus
Nitrogen
Potassium
When reading the label
on a bag of fertilizer,
the 3 numbers on the
bottom stand for
Nitrogen
Phosphorus
Potassium
Organic matter is plant and animal remains in various stages of decay.
The decaying organic matter releases nutrients
These soils are dark brown or black, are high in nutrients, and hold a lot of water
Soils with high organic matter are more productive
The soil is more easily tilled and made into a seedbed for planting
Minimum and no-till farming is a practice where soil is left alone between crops. It increases the amount of water and organic matter in the soil and decreases erosion
Water is an important nutrient for plant growth.
It is held between soil particles and sticks to their surfaces
Soil that is too wet or too dry will not support the growth of most crops and ornamental plants
Air also fills spaces between soil particles
Plant roots need air to live and grow
Some plants adapt to different environments
For example:
Cypress trees grow in wet places. For these trees to have hair, the roots grow structures known as “knees”. The knees rise a few feet above the water level.
A way of looking at a cross section of soil
Soil has layers known as horizons
O Layer: Organic Material
A Layer: Topsoil
B Layer: Subsoil
C Layer/Bedrock
Color of soil comes from minerals and organic matter
Indicates the quality of the soil
Dark brown or black=High in organic matter The darker the soil, the higher the amount of organic
material
Red or yellow=High in iron
Gray=Poor drainage
White=Low nutrient levels
Spotted appearance=“Mottling”…due to variability of moisture in the soil
3 groups:
Organic Elements: Carbon
Hydrogen
Oxygen
Major Elements: Nitrogen
Phosphorus
Potassium
Minor Elements: Other elements required in small amounts for plant growth
pH=Acidity or Basicity
pH is based on a scale from 1 to 14
1=Most acidic
14=Most basic
7=Neutral
Most soils are between 4-9
Most plants do well in an acidic soil-6.6 being the best
What is soil erosion? Soil erosion is the removal of soil by water and wind.
What causes soil erosion? slope
water splash, runoff
wind drying and blowing soil
accelerated erosion caused by farming and construction
Sheet Erosion: The gradual and fairly uniform removal of surface soil
Caused by splash erosion and slow runoff
Rill erosion is small streamlets that are cut into the soil surface by running water.
Caused by runoff
Gully erosion is rills that have become extremely large.
Caused by uncontrolled runoff for an extended period of time.
Sandblows are the result of wind picking up soil particles and carrying them away.
Caused by the removal of vegetative cover, which allows the soil to become dry and loose.
Plant Trees
Terraces
No/Minimal Till Farming
Contour Plowing
Crop rotation
Soil pH
Water in the Soil
Salinity Management
Soil Organisms
Indigenous Crops
10 Ways to Conserve Soil