Soil Origin and Development

1. Soil Origin and Development South Central Agriculture Science Academy

2. Mineral Matter Mineral matter includes rock and mineral fragments These fragments are classified by size: • Gravel • Sand • Silt • Clay

3. Definitions • Pedology = study of soil formation • Eluviation = removal of material, such as clay or nutrients from a layer of soil by percolating water • Leaching = when water passes through the soil profile and removes chemical compounds or nutrients from the soil in solution

4. Visit the text book • How does climate effect how soil is formed? Visit page 98 please to answer the question.

5. The Components Soils have four main components that make up the whole

6. Organic Matter Organic Matter includes things, such as: • Plant roots • Decaying leaves and other vegetative parts • Animals: • Microorganisms (i.e., nematodes and fungi) • Insects (i.e., larva and worms) • Small mammals (i.e., gophers and moles)

7. Animals that help with O.M. Visit this site: http://school.discoveryeducation.com/schooladventures/soil/field_guide.html What are the 7 common groups of creatures found in soil? What are each used for?

8. What is O.M. ?? • 1. Is the portion of the soil which includes animal and plant remains at stages of decay • Forest= leaves, dead trees, • Prairies=grass roots and tops • Farmland= crop residue

9. Chemical Makeup of O.M. • 1. Consists of complex carbon-containing compounds • 2. Long chains are formed and other elements use these to make more organic compounds

10. Chemical Makeup of O.M • 3. The most important compounds are • A. Carbohydrates: simple sugars, starches, and cellulose • B. Lignins: is 10-30% of plant tissue, makes plants rigid, resists decay

11. Chemical Makeup of O.M • C. Protein • Amino acid chains • Supplies Nitrogen when broken down

12. Decomposition • 1. Micro-organisms digest organic matter • 2. Releases CO2 and H2O • 3. Carbohydrates are first to be consumed • 4. Lignin-becomes humus and slowly broke down

13. Decomposition • 5. Decay Organisms need O2 and microorganisms use O2 to oxidize the different compounds • 6. 1st breakdown is quick and requires weeks or months

14. Factors affecting O.M. • 1. Vegetation • 2 times as much o.m. on grassland to woodland • O.M. is deeper in prairie soil and is in soil

15. Factors affecting O.M. • 2. Climate • Arid conditions soil has less O.M. • High temperatures decay O.M. more rapidly

16. Factors affecting O.M. • 3. Texture • Fine textured soils hold more organic material because clay protects hums from decay

17. Factors affecting O.M • 4. Tillage • Prairie will return more than cropping

18. Functions of O.M. • A. Nutrient and water storage • 1. O.M. stores many of the nutrients used by plants and does it in 2 different ways • Colloids hold water and nutrients • O.M. stores nutrients as part of its own makeup

19. Functions of O.M. • 2. Both humus and O.M. absorb water like a sponge, humus can store 6 times its own weight

20. Functions of O.M. • B. Nutrient Availability • Makes several nutrients more available for plant use

21. Functions of O.M • C. Soil Aggregation (Mixing) • 1. Heavy clay responds best. Breaks down particles, aerates, and makes easier to work with

22. Functions of O.M • D. Prevents Erosion • 1. Soils kept supplied with O.M. have improved structure that improves water infiltration • 2. Stops excessive water runoff • 3. Increasing O.M. from 1-3% will reduce erosion up to 1/3

23. Functions of O.M. • Undesirable Effects • 1. Nitrogen is immobilized or tied up during the decay process and is unavailable to plants • 2. Certain plant residues are toxic to other plants

24. Maintaining Soil O.M. • A. It is impractical and not economical to raise O.M. levels significantly but should be a goal to maintain at highest levels • B. Adding fresh organic matter will improve soil the best

25. Maintaining Soil O.M. • C. Crop Residues • Leave all crop materials possible. Don’t burn residues, harvest some • Use good fertilizer, healthy plants make more residue

26. Maintaining Soil O.M. • D. Green Manure • 1. Turn over alfalfa, clover, sudan grass, will increase N levels • 2. Increases O.M. levels and fixes more nutrients

27. Maintaining Soil O.M. • E. Crop Rotation • 1. A rotation between row crops, small grains, and legumes is better for keeping high O.M.

28. Maintaining Soil O.M. • F. Organic Matter Additions • 1. Animal Manures, sludge, organic wastes • 2. Industries may provide organic wastes, by products, meat scraps, etc.

29. Maintaining Soil O.M. • G. Mulches • 1. Not economical in large acres • 2. Reduce tillage leaves some mulch • 3. Limits water evaporation, keeps soil temperature cooler on hot days, and warmer at night

30. Maintaining Soil O.M. • H. Conservation Tillage • 1. Conserves topsoil which is high in O.M. • 2. Crop residue decays slower when left on top • 3. No till soils are high in O.M. in the top layer

31. Air • Soil air is trapped in pores of the soil. • Porosity is a term to define how much open space is available for air and water to be held in the soil. • Air provides oxygen for plant roots.

32. Water • Soil water is held by soil particles. This allows the water to be available for plants. • Organic matter is attributed to holding more water because it creates pores and may even absorb water like a sponge.

33. Soil Body • Physical Weathering- • refers to the effects of such climatic factors as Temperature, water, and wind. One of the most important is frost wedging. • Chemical Weathering- changes the chemical makeup of rock and breaks it down. • Hydrolysis- water reacts with minerals to produce new and softer compounds

34. The Soil Profile • Soil does change over time today Scientist have classified them into four areas • They are: • Addition • Losses • Translocations • Transformations

35. The Soil Profile • What is Additions? • It is materials such as fallen leaves windblown dust or chemicals from air pollution may be added to the soil

36. The Soil Profile • What is Losses? • It is materials that may be lost from the soil as a result of deep leaching or erosion from the surface.

37. The Soil Profile • What is Translocation? • It is materials that may be moved within the soil as with leaching deeper into the soil or being carried upward with evaporating water.

38. The Soil Profile • What is Transformation? • It is the materials that may be altered in the soil, for example organic matter decay weathering of the minerals to smaller particles or chemical reactions.

39. The Soil Profile • Each of these processes will occur at different depths of the soil. • For example: • Organic Matter will be at the top or the near the surface of the soil.

40. The Soil Profile • What is a soil profile? • It is the vertical section through the soil and extending into the unwreathered parent materials and exposing all the horizons.

41. Master Horizons • What is the Master Horizons? • The are A, B and C horizons are known as the master horizons. They are a part of a system for naming soil horizons in which each layer is identified by a code O, A, E, B, C and R

42. Horizons • The O Horizon- • Is the organic layer made of wholly or partially decayed plant material and animal debris . You can normally find this layer in a forest with fallen leaves, branches and other debris.

43. Horizons • The A Horizon- • It is usually called the topsoil by most farmers. This is where the organic matter accumulates over time. This layer is very prone to leaching and losing iron and other minerals. The A horizon provides the best environment for the growth of plant roots, microorganisms and other life.

44. Horizons • The E Horizon- • This is the zone of the greatest leaching of clay, chemicals and organic matter.

45. Horizons • The B Horizon- • This is also called the subsoil is often called the zone of accumulation where chemicals leached out of the A horizon

46. Horizons • The C Horizon- • lacks the properties of the A and B horizon. It is the soil layer that is less touched by soil forming processes and is usually the parent material soil

47. Horizons • The R Horizon- • is the underlying bedrock such as the limestone, sandstone, and or granite.

48. 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.