1 / 15

Into the Depths

Into the Depths. Introduction to Agriculture, Food, and Natural Resources. Unit 3 – Lesson 3.4 The Whole Soil. Soil Layers. Horizons vary depending upon the make up of Particle sizes How the particles are arranged Color Parent Material Drainage Organic Matter Content.

hayley-hill
Télécharger la présentation

Into the Depths

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Into the Depths Introduction to Agriculture, Food, and Natural Resources Unit 3 – Lesson 3.4 The Whole Soil

  2. Soil Layers Horizons vary depending upon the make up of • Particle sizes • How the particles are arranged • Color • Parent Material • Drainage • Organic Matter Content Soil is typically formed over time in distinct layers called horizons.

  3. Soil Profile O – organic A – topsoil B – subsoil C – parent material R – bedrock Vertical section of soil consisting of soil horizons United States Department of Agriculture, Natural Resources Conservation Service. (2010). A soil profile. Retrieved from http://soils.usda.gov/education/resources/lessons/profile/

  4. Horizons • Organic (O) • Also called litter layer • Comprised of whole or partially decayed organic matter • Topsoil (A) • Dark in color • Comprised of decayed organic matter and aged mineral matter • Best environment for root growth

  5. Horizons • Subsoil (B) • Lighter in color • Mostly mineral matter, little organic matter • Tend to be high in clay • Parent material (C) • Parent material, soft, weathered bedrock • Bedrock (R) • Un-weathered

  6. Soil Color • Influenced greatly by organic matter and iron • Dark colors indicate high levels of humus (organic matter), typically fertile soils • Gray indicates wetness or no organic matter • Brown and red indicate presence of iron, typically are well-aerated

  7. Soil Structure When soil particles cling together in an arrangement known as a ped, the shape of the ped is called structure. Two considerations must be made for soil structure: • Structure type • Structure grade

  8. Structure Type The shape of the ped formed is called structure type. Granular – roughly spherical, like grape nuts. Usually 1-10 mm in diameter. Most common in A horizons. Platy – flat peds that lie horizontally in the soil.

  9. More Defined Structure Types Blocky – roughly cube-shaped, with more or less flat surfaces. Blocky structures are typical of B horizons. Prismatic – larger, vertically elongated blocks, often with five sides.

  10. Structureless Types Massive – compact, coherent soil not separated into peds of any kind. Single grain – in very sandy soils, every grain acts independently. Structureless soils are not ideal for most crop use.

  11. Structure Grade • How distinct the shape of the ped is. • How well the ped holds the shape. • Four grades define soils: • Strong • Moderate • Weak • Structureless

  12. Effects of Structure Good structure, or strong structure, means good aeration because of ample pore space. Organic matter is important for forming soil structure. • Increases porosity • Contributes to water holding capacity

  13. Effective Depth Relative to structure is a soil evaluation category called effective depth. Effective depth is the zone in which plant roots can easily grow.

  14. References Huddleston, J. H., & Kling, G. F. (1996). Manual for judging Oregon soils. Corvallis, OR: Oregon State University. Parker, R. (2010). Plant and soil science: Fundamentals and applications. Clifton Park, NY: Delmar. Plaster, E. J. (2003). Soil science & management (4th ed.). Clifton Park, NY: Delmar.

More Related