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