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Soils

Learn about the composition and formation of soil, including its textures, horizons, and water relationship. Explore the chemical properties of soil, such as pH and cation exchange capacity. Discover soil classification and how it can help with soil management techniques to mitigate erosion and improve fertility.

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Soils

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  1. Soils Chapter 5

  2. SOIL • Is the soft material that covers the surface of the earth and provides a place for the growth of plant roots. • It also contains minerals, organic matter, air, and water.

  3. Parent Material Igneous rocks – heat created from deep in the earth. Granite, quartz Sedimentary rocks – formed by moving particles (wind water and glacial) and then recombining. Limestone, sandstone Metamorphic – rocks that have changed due to high pressure and or high heat. Marble and slate

  4. Formation of Soil(weathering) • Water • Movement • Freezing • Wind • Glacial • Chemical • Temperature • Mechanical • Roots, earthquakes, landslides

  5. Five factors control soil formation • Parent material • Time • Climate • Vegetation • Topography

  6. Composition of soil.

  7. Soil Textures is the amount of sand, silt and clay in the soil. Clay – fine and plate like, holds a tremendous amount of water and nutrients poor drainage. Smallest Silt – in between particle between clay and sand. Medium. Sand – excellent drainage, warms up quickly in the Spring, poor water retention and fertility. Largest.

  8. Texture Triangle

  9. Soil Profile • Refers to the arrangement and properties of the various soil layers. • Top soil • Sub soil • Parent Material

  10. Soil Horizons • O Horizon • A Horizon • B Horizon • C Horizon • Depth & Colors

  11. Soil Water Relationship • Why is water needed in the soil? • Movement of minerals into the plant • Movement of glucose • Photosynthesis • Cooling • Water types • Gravitational water • Capillary water • Hygroscopic water • Crystal lattice water

  12. Soil Water Relationship cont. 1) Hygroscopic Water is held so strongly by the soil particles (adhesion), that it is not available to the plants 2) Capillary Water is held by cohesive forces greater than gravity and is available to plants 3) Gravitational Water is that water which cannot be held against gravity • as water is pulled down through the soil, nutrients are "leached" out of the soil (nitrogen)

  13. Saturation Percentage • Immediately following an irrigation, the film of water is thick, and smaller pores are full of water. The soil particles can not hold the water. It is easily lost to the plant. • 1/10 Atmosphere (Near Saturation)

  14. What is Field Capacity? • when the soil contains the maximum amount of available water, the greatest amount of water it can hold against gravity. • 1/3 Atmosphere • ½ saturation %

  15. What is Permanent Wilting Point? • the soil has so little water, that plants can no longer recover from wilting. • roots can no longer take in water. • 15 Atmospheres. • ¼ Saturation %

  16. What is Available Water? • the amount of water between field capacity and wilting point

  17. Chemical Properties • Soil pH • The amount of hydrogen ions in the soil. • Soil pH range is 0 to 14. • Acid soil is soil with a pH below a 6.9 -Probably high rainfall and possibly high in organic matter. -Use lime to raise pH -Many fertilizers have an acid affect on the soil.

  18. pH cont. • Alkaline soil is that which is above a pH of 7.1 -Low rainfall areas -Use sulfur to lower pH • Neutral at a pH of 7 -Gypsum acts a buffering agent

  19. Cation Exchange Capacity Used to determine fertilization schedules

  20. Cation Exchange CapacityCEC • This gives you information of for fertile your soil is. • This will tell you how much nitrogen your soil can hold. • You will use this number to create your fertilizing schedule or program.

  21. CEC • The amount of clay and organic matter play a large role in the amount of nitrogen your soil can hold. • CEC # x 10 = Total Nitrogen the soil can hold

  22. Base Saturation • Calcium, Ca = 65-80% • Magnesium, Mg = 12-25% • Potassium, K = 4-8% • Hydrogen, H = less than 10% • Sodium, Na = less than 1%

  23. Sodic and Saline Soils – High amounts of sodium with a pH of 8.5 or above. • Saline-sodic Soils = same as Sodic but with a pH of 8.4 or below.

  24. Organic Matter • Improves physical condition & structure. • Increase water infiltration. • Decrease erosion losses. • Supply plant nutrients. • Micro-Organisms enrich the soil.

  25. Soil Classification • Why classify soil? • How can it help you?

  26. Soil Management • Erosion • Sheet & Rill • Gully • Conservation • Contour Cropping • Strip cropping • Terraces • Grass Waterways • Conservation Tillage • No-Till • Minimal Till • Ridge Planting System

  27. Contour Farming • practice of tilling sloped land along lines of consistent elevation in order to conserve rainwater and to reduce soil losses from surface erosion. These objectives are achieved by means of furrows, crop rows, and wheel tracks across slopes, all of which act as reservoirs to catch and retain rainwater, thus permitting increased infiltration and more uniform distribution of the water.

  28. Contour Cropping

  29. Strip Cropping • is a method of farming which involves cultivating a field partitioned into long, narrow strips which are alternated in a crop rotation system. It is used when a slope is too steep or when there is no alternative method of preventing soil erosion.

  30. Strip cropping

  31. Terrace Farming • is a piece of sloped plane that has been cut into a series of successively receding flat surfaces or platforms, which resemble steps, for the purposes of more effective farming. This type of landscaping, therefore, is called terracing. Graduated terrace steps are commonly used to farm on hilly or mountainous terrain.

  32. Terraces

  33. Grass Waterways

  34. Grass Waterway • consists in a 2-metre (6.6 ft) to 48-metre-wide (157 ft) native grassland strip of green belt. It is generally installed in the thalweg, the deepest continuous line along a valley or watercourse, of a cultivated dry valley in order to control erosion.

  35. Soil Compaction • What is soil compaction?

  36. Soil Compaction • How do we prevent soil compaction? • How do we repair soil that is compacted?

  37. Deep Tillage • 1. Can be 2-6 feet deep or even more • 2. Ripper (Fig. 9-12) • 3. Slip Plow (Fig 9-11) • 4. Used to break up restriction layers and hardpan.

  38. Ripping or Chiseling

  39. Ripper

  40. Minimum Tillage (No Till) • 1. The practice of almost no land prep. Just very little.

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