Chapter 2- Soils

What is Soil? soil is the mineral and organic matter that supports plant growth on the earth's surface. It is a mixture of particles of rock, organic materials, living organisms, air and water.

Who depends on soil? farmers & ranchers anyone needing food, clothing, building materials, minerals construction trades (buildings, roads etc.)

The success of farmers determines the income of who? entire community merchants

A knowledge of soil management is helpful in what occupational areas? crop production livestock production horticulture engineering forestry soil scientist soil conservationist

What are some agencies which promote soil conservation? Local & County : NRCS, Cooperative Extension Service, High School Ag Dept. State : Cooperative Extension Service, NRCS Federal : Cooperative Extension Service, NRCS, USDA, BLM, Dept.of Fish Wildlife & Parks

How long does it take to create soil? It takes 100 to 400 years to create 1" of topsoil.

Soil origin All soils come from matter called parent material. Parent material can be organic or inorganic, most soils are a combination of the two. Soils that originate from minerals are the result of decomposition of rock materials is inorganic soils.

Inorganic soils The process is the result of wearing away of rock by actions of the weather. Water- Deposited Soils: alluvial soils – Lacustrine deposits: soils left after lakes dry up – Marine sediments: shore lines recedes and leaves sediments on the dry land.

Volcanoes- bring deposits from deep within the earth Soils deposited by Wind- Aeolian soils creating sand dunes with sand particles. – Loess soils: fine soil particles like silt and clay deposited by wind

What is Organic Matter? all plant and animal residues in the soil

What two things have greatly lowered the Organic Matter content of soil? soil erosion & continuous cropping

How can organic matter be increased? crop residues barnyard manure green manure

What is Green Manure? a crop grown for its organic matter green manure crops are generally plowed under while they are still green

What other things make up soil organic matter? decomposed carcasses and excrements of worms, insects, larger animals and microorganisms

What is Mineralization? organic matter is broken down into simple mineral compounds

When organic matter breaks down, what is released for the crop's use? nutrients

How does Organic Matter Improve Soil? 1) increase water holding capacity 2) nutrients attach to O.M. 3) O.M. improves tilth (aggregate) The amount of humus in soil is directly proportional to the amount of nitrogen in soil Soils high in O.M. are easily worked and may be described as having good tilth.

Benefits of Organic Matter Organic Matter promotes granulation of soil by binding soil particles into granules. O.M. makes clay soils less sticky and improve tilth. Deeper root growth and water entry and storage are improved as well as aeration of the soil. Helps with reducing soil compaction and improves air space in soil.

Organic Matter & Sandy Soils Sandy soils have good aeration but dry out quickly. Sandy soils increase water holding capacity and have less erosion as O.M. is added?

What is the largest source of O.M. in the soil? plant roots

Which is the most preferred green manure, legumes or non- legumes? legumes- added nitrogen

What is nitrogen tie-up? microorganisms in the soil use the nitrogen in the soil to break down organic matter, thus it is temporarily "tied up" (used as food) this is very important when considering recropping and not allowing the soil to have a year in fallow to allow for mineralization in order to reduce the nitrogen tie-up.

How many square feet are in an acre? 43,560

Soil Ingredients Mineral Matter 45% Water 25% Air 25% Organic Matter (OM) 5%

Soil can be described by color. Color is a result of the parent materials or bedrock that the soil originated from. Soils that are deep orange or reddish in color are usually high in iron. Dark brown and black soils are high in organic matter.

Activity In groups of 3 students will crate a Promotional Flyer for organic matter. – What is O.M. – Why use O.M. – What types of O.M. is available – Identify your target market: who are you trying to get to purchase O.M. – Use pictures and illustrations and color

Physical Properties of Soils Physical characteristics Texture, structure, and consistency Determined to a large degree on how usable and productive the soil will be. – How quickly water penetrates – How well water stays in the soil – How soil holds up under machinery – The ease of root penetration – Aeration of the soil

Soil Texture Refers to the size of the individual soil particles, called soil separates. Larger soil size the coarser the soil feels Largest Sand Silt Clay smallest

Activity 1- Chapter 2 Objectives: 1.Identify the 3 soil textures 2.Describe the characteristics of each texture 3.Identify the strengths and weaknesses of each texture. 4.Explain how agriculture deals with sols that have different types of soil texture. Directions: Create a poster that illustrates the above 4 objectives. SandSiltClay Size Characteristics Strength/weakness Agriculture use:

Soil Conservation A typical farmer is doing a "good job" of soil conservation if he loses less than 1/16" of topsoil each year. How many pounds of soil does he/she lose each year if he/she loses 1/16"? How many tons?(extra credit)

What is Soil Management? the science of the tillage, cropping practices, and treatment of a soil for the production of plants good soil management results in better yields and lower cost per unit of production

Soil pH Use pH overhead Chemical makeup of clay usually results in a negative charge and nutrients result in a positive charge increasing cation exchange(soils ability to hold onto nutrients). Leaching cause the loss of soil nutrients through water flow the soil. – Sand = – Silt = – Clay =

Soil Structure The grouping or clinging of soil particles are called? Peds or soil aggregates Peds held together by clay and humus (O.M) in the soil. The rate at which water flows through the soil is greatly influenced by the structure of the soil.

Types of Peds

Classes or Sizes of Soil Very fine Fine Medium Coarse Very coarse

Structured soils grade Weak structure: Moderate structure: Strong structure:

Soil Taxonomy Organization of soils Orders: 11 orders of soil Subgroups: 47 Great groups 185 Subgroups 970 Families 4500 Soil series 12620

Activity #2 graphic organizer Soil taxonomy

Soil Ecosystem