Soil Structure and Formation

Objectives Review Soil Texture Review Soil Formation Learn about Soil Structure Learn about Soil Function

Soil Structure and Function Soil Texture Review Clay Silt Sand

Which particle (texture size) is the smallest? The largest? Clay is the smallest particle size >0.002 mm Can hold water and become very dry causing cracking. Holds onto nitrogen Silt is the median particle size 0.002-0.05mm Gives a very smooth feel to soil Sand is the largest particle size 0.05-2 mm. Gives a gritty feeling Adds ability to infiltrate water.

Soil Textures

Soil Structure and Function Soil Formation Review Parent Material Time Climate Relief Organisms

Formation of Soil A base material=parent material (PM) When the soil is similar to the PM it is a young soil We need time to breakdown the PM and add organic matter Time is required to weather and change and incorporate other material from the surround. Climate Moisture and Temperature These two factors increase decomposition and weathering of PM and organic matter Relief=position of where soil is located The position of where the soil is located and dictate how it forms and how much nutrients or water is in it. Organisms=The garbage disposals of the soil Insects, microbes, invertebrates, etc. that chew up and process organic matter.

Soil Structure and Function Soil Structure Review

What is Soil Structure? The arrangement of the solid parts of the soil in conjunction with pore spaces. This determines how individuals soil granules clump to aggregate This then alters how plants can grown, how organisms live and how air and water move through the soil.

What is Soil Structure? Soil particles (sand, silt and clay) that arranged into clusters or aggregates of varying size. Aggregates that are naturally occurring are peds. Aggregates that are created by tillage or are not natural are clods.

What is Soil Structure? What types of structures are in soil?

What is Soil Structure?

What is Soil Structure? How is structure formed? A clump is formed by: Soil particles sticking together via: Plant roots in the soil separate clumps Freezing or thawing of soils changes clumps Soil wetting and then drying Tillage Microbial activity

What is Soil Structure? How is structure formed? Cementing of weaker aggregates to become strong Microbial exudates Plant root exudates Clay, organic matter or oxides act as cements.

What is Soil Structure? Why is Structure Important? Improves tilth Tilth=soil physical condition Improves permeability Permeability=ability to transmit water and air. Resists crusting A lid on the soil that prevents crop growth, aeration and infiltration.

Soil Structure and Function Soil Function Review

What is Soil Function? There are 5 (F-I-V-E) key functions Medium for plant growth Water regulator Recycler of Raw Material Home for organisms Landscaping and engineering medium

What is Medium for Plant Growth? An anchor for plant roots Holds water for growth Holds nutrients to support plants to take root. Soil properties needed for plant growth and optimum medium: Soil texture-Greater organic matter and clay content=greater fertility=more gowning capacity Aggregation Porosity Aeration Water holding capacity

What is Water Regulation? Ability for soil to absorb, or store moisture for later use Moisture can be rain or snow. This allows for available water for plants and soil organisms to use. Major regulator in soil of water is Organic matter 1% of organic matter increases water holding capacity by 1 inch! Water infiltration is a factor of: Texture, tilth and plant cover

What is Recycler of Raw Material? Soil is the #1 Decomposer….or home of it! Decomposition of dead plants, animals and organisms by soil flora and fauna. This process takes organic materials and makes then inorganic or usable items. Organic are Carbon containing items that are locked up in tissue. Inorganic are non Carbon containing items that are available for use to build tissue. The flora and fauna make humus! A great nutrient.

What is Home for Soil Organisms? Soil is the place that the primary decomposers, microorganisms call home. It provides, air, food, water and shelter from the elements for these organisms.

What is Landscaping and Engineering material? Soil is the main material we build on, drive on and live on! What the texture of the soil is How it holds water Its structure And its mineral content ALL AFFECT building.

Soil Thoughts Think about what we know about our landscape What is the Soil like in El Reno? Color, Feel, Smell, How is it used? Who lives in it? What grows on it? What about a forest in Minnesota? A Forest in Maine? A Forest in Florida? A Forest in Eastern Oklahoma? A forest of the Rocky Mountains? Think about the Northern Great Plains, Central Great Plains and Southern Great Plains?

Assignment Upload your description of El Reno soil and choose what you think another soil will be like (mountain, glacial, bottom of the lake, desert, etc). Base your description off of: Color, Feel, Smell, How is it used? Who lives in it? What grows on it? Upload in word format onto approriate site: Weebly or Blackboard. Include in the write-up where you would like to live most and why?