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The Dirt on Soil! An Introduction to Soil Chemistry

The Dirt on Soil! An Introduction to Soil Chemistry. Mrs. Long Horticulture I Fall 2013. What is soil?. Soil is the unconsolidated cover on the surface of the earth. Soil is made up of mineral particles, organic particles, air and water. Soil is capable of supporting plant growth.

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The Dirt on Soil! An Introduction to Soil Chemistry

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  1. The Dirt on Soil!An Introduction to Soil Chemistry Mrs. Long Horticulture I Fall 2013

  2. What is soil? • Soil is the unconsolidated cover on the surface of the earth. • Soil is made up of mineral particles, organic particles, air and water. • Soil is capable of supporting plant growth.

  3. About ½ of the soil volume is solid particles About ½ of the soil volume is pore space Soil ComponentsThe 4 parts of soil

  4. Functions of agricultural soils • Anchor plant roots • Supply water to plant roots • Provide air for plant roots • Furnish nutrients for plant growth • Release water with low levels of nutrients

  5. Soil StructureThe arrangement of sand, silt, and clay particles to form larger aggregates. How they fit together! • Organic matter is the glue that holds the aggregates together • Large pores (spaces) between aggregates are filled with air in a moist soil. • Small pores are filled with water in a moist soil. Even smaller pores inside the aggregates (not shown) are also filled with water. 1/10 inch

  6. Soil Structure • Sand • Loose • Silty • Granular • Clayey • Platy or Blocky

  7. 1/100 in Soil Texture • The mineral part of soil consists of sand, silt, and clay particles • Sand – Largest particles – low moisture holding capacity • Silt – Medium particles – good moisture holding • Clay – Smallest particles – Hold a lot of water • Loam – equal parts sand, silt, clay – ideal texture! Sand 0.1 – 0.002 in 2 – 0.05 mm Silt 0.002 – 0.0001 in 0.05 - 0.002 mm Clay Less than 0.0001 in Less than 0.002 mm

  8. Where does soil come from? • Parent Material • Mechanical weathering – breaks down rock into smaller pieces without changing soil chemistry • Chemical weathering – breaks down rocks into smaller pieces by chemical reaction • Biological weathering – results from activities of living organisms

  9. Mechanical Weathering

  10. Chemical Weathering

  11. Biological Weathering

  12. Homework for 04/ • Bring a small soil sample from your yard at home. • Make sure its clean. • Bring in a full quart-sized ziploc bag full of soil • YOUR NAME has to be on it!!

  13. Soil Sampling 5.02 Discuss the soil profile and soil sampling for surface and subsurface layers. 10/31/12

  14. Before we start today: • Soil Particle Size Lab (Part I) • Take your soil sample (1 per group) • Place a cup full of soil into a jar • Fill the jar to the top with water and tighten the lid. • Shake for 3 minutes. • Set to side (labeled) until tomorrow!

  15. Soil Layers • Soil layers are called horizons. • Layers parallel to earth’s surface • Defined usually by color, texture and physical features.

  16. O horizon • The O horizon contain Organic matter • Uppermost dark Colored • Most fertile • Made of leaves, twigs, waste, decaying matter

  17. A horizon • Topsoil • Porous mix of humus • Just below the O • Home to earthworms and microorganisms • Brown in color

  18. B horizon • Subsoil • Clayey with high mineral content • Brownish red • Receives a lot of leached material

  19. C horizon • Parent material • Clumps of unweathered rocks

  20. R horizon • Bedrock • Cannot be dug by hand • Very few roots can penetrate

  21. Purpose • Determines levels of fertility in soil • Use this information to make accurate fertilizer recommendations for growing plants • A soil test shows deficiencies, excesses and imbalances can be avoided.

  22. The Soil Testing Laboratory • Kits are available at local garden centers • Submit samples to NC Dept of Agriculture and Consumer Service Agronomic Division • https://www.youtube.com/watch?v=vb5wtgaKGUs

  23. Lime & Fertilizer Recommendations • Information from a soil test will help you select the proper liming and fertilization program to obtain optimal growth of lawn, garden and ornamental plants.

  24. Step 1 • Create a visual grid of the area to be planted. • 5-10 subsamples from the site • Sample before the growing season

  25. Step 2 • Use a stainless steel soil-sampling probe • Take the surface sample to tillage depth • 4 inches for lawns • 6-8 inches for crops

  26. Step 3 • Mix soil samples together.

  27. Step 4 • Remove any: • Grass • Rocks • Any other material • SOIL ONLY!!

  28. Step 5 • Place soil samples in a box • Get one from County Extension • Also need Soil Sample Information Sheet

  29. Step 6 • Send soil tests to Raleigh • Free for residents • NCDA&CS Agronomic Services DivisionMailing Address: 1040 Mail Service Center, Raleigh NC 27699-1040Physical Address: 4300 Reedy Creek Road, Raleigh NC 27607-6465Phone: (919) 733-2655; FAX: (919) 733-2837

  30. Classwork • Perform the: • Soil Testing Webquest (Activity 5.02.02)

  31. Today’s Lineup • Making “Dirt” • Bedrock at bottom - R • Parent material - C • Subsoil - B • Topsoil - A • Organic matter – O

  32. Types of Horticulture Soils

  33. Peat Moss • Organic • Partially decomposed material from Swamps • Holds moisture

  34. Perlite • Inorganic • Natural volcanic material • Helps with soil aeration and water holding capacity

  35. Organic Organic Matter Compost • Dead plant or animal tissue • Contains Carbon! • Decayed organic matter • Used for soil conditioning • Fertilizer

  36. Bark • Organic • Larger matter • Promotes drainage • Mainly for trees and shrubs

  37. Sphagnum Moss • Organic • Dehydrated bog plants • Holds moisture • Very acidic • Hanging baskets

  38. Horticulture Soils Advantages Disadvantages • Sterile • pH is neutral • Disease and weed free • Good for starting plants • Easy to mix • Improves plant uniformity • Expensive • Light weight

  39. Hydroponics • The process of growing plants without soil.

  40. Advantage of Hydroponics • No soil & problems associated with soil. • Easy to control nutrient content of plants.

  41. Disadvantages of Hydroponics • Plant support must be provided with strings, wires, or stakes. • Water quality must be high. • Diseases spread through water. • More moisture or humidity in air to cause favorable environment for disease organisms. • More expensive.

  42. Hydroponic Lettuce

  43. Background on Today’s Lab

  44. pH • Soil pH is a measure of the acidity or alkalinity of soils • pH ranges from 0-14, 7 being neutral • Ideal pH is 5.5-7.5

  45. pH Lime Calcium/Sulfur • Raises the soil pH • Lowers the soil pH

  46. Soil Texture Triangle • Give names to soils combos • Clay • Sandy Clay • Silty Clay • Clay Loam • Sandy Clay Loam • Silty Clay Loam • Loam • Sandy Loam • Silty Loam • Sand • Loamy Sand • Silt

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