Soil Science
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Soil Science

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    Soil Science Soil Science Presentation Transcript

    • Soils Ag Science
    • Soil
      • Soil is a layer on the earth’s crust that provides a combination of resources. Allow for the growth of plants and animals.
        • Oxygen – needed for adequate root growth
        • Temperature – soil absorbs heat from the sun. Used for plant growth and seed germination
        • C. Water – used for plant growth
        • D. Carbon – utilized in the form of organic matter
        • E. Nutrients – provided as minerals. Broken down as nitrogen and recycled through decaying material.
    • II. Soil is composed of 4 different components.
      • Solid Portion (50%)
        • Mineral Matter – 45% of the soil. Partially decomposed rock, ie. sand, silt, clay
        • Organic Matter - ~5% of the soil. Partially decomposed plant & animal material. Gives soil its color
      • B. Pore spaces (50% of the soil)
      • 1. Air – accounts for 25% of the soil. When soils are wet, less air. When soils are dry, more air.
      • 2. Water – accounts for 25% of the soil. When it rains, water either enters the soil or runs off.
      • Water cont.
      • Infiltration – process of water soaking into the soil.
      • Once water is in the soil, the movement downward is called percolation .
      • A soil that allows for both is called permeable
      • Water in the soil my be one of three types
        • Gravitational water – water that drains through the pore spaces (leaching occurs)
        • Capillary water – water that is held between particles of soil against forces of gravity; may move upward or sideways
        • Hygroscopic water – water that forms a thin film around individual soil particles; unavailable to plants.
    • III. Abundant life can be found in soil.
      • Forms of life in the soil include:
        • Earthworms
        • Insects
        • Bacteria
        • Fungi
        • Other organisms
      • Bacteria & fungi have an important role in the soil. They breakdown o.m. and release nutrients
      • C. Earworms, ants, crawfish, moles, and other organisms improve the tilth, or ease at which soil can be worked.
      • These organisms create openings in the soil as they tunnel. This helps drainage and improves gas exchange.
    • IV. Plants depend on soil to provide 4 basic needs.
      • A. Anchorage – soil acts to provide a firm support as roots grow throughout the soil.
      • B. Water – soil provides nearly all of the water used by plants. Water is absorbed through the plants’ roots.
      • C. Oxygen – nearly all organisms need oxygen. Roots don’t have ample supplies, so they need good soil aeration to allow gas exchange.
      • D. Nutrients – of the 16 nutrients considered to be essential for plant growth, 13 are obtained from the soil. Root hairs absorb the nutrients dissolved in soil water.
    • V. Ag depends on soil to grow food, fiber, and other plants.
      • Cropland – land on which soil is worked
      • Grazing land – land used for grazing cattle and sheep; perennial forage.
      • Forests – land used for growing trees, which is later harvested
      • Water structures – ponds and other reservoirs are constructed out of soil.
    • Non-ag uses of soil
      • Recreation – playgrounds, sports fields, jogging paths, golf courses, parks, camp grounds,etc.
      • Foundations – buildings depend on a solid soil base upon which a building is to be built and remain sound.
      • Waste disposal – used for the treatment of human sanitary wastes.
      • Building materials – build underground, into hillsides, adobe
    • Five factors that affect soil formation
      • A. Parent Material – type of rock that soil is made from.
      Igneous sedimentary metamorphic
      • B. Climate – temperature & moisture
      • C. Living organisms – organisms (bugs & worms) and plants in the soil.
      • D. Topography – hills and valleys
      • E. Time or weathering – age of the soil and climate
    • THE MAIN KINDS OF SOIL PARENT MATERIALS Parent material is formed by the disintegration and decomposition of rock
      • A. Most soils in Illinois were formed by glaciers.
    • Newer and more productive Older and less productive
      • B. About 64% of the soil is formed from loess. Loess occurred from the
      • blowing of the soil after the
      • glaciers.
      • C. About 7% of the state soil is due to recent stream deposits. This is referred to as alluvium .
      • D. Bedrock – most of the shale, sandstone, or limestone bedrock in Illinois is buried by loess. Except in extreme NW and Southern Illinois.
      • Organic soils – less than 1% of the soils in Illinois are classified as organic. Occur where formerly shallow ponds or supported swamp vegetation. Wet conditions slow decay of organic materials.
        • Two types: muck and peat
      • Topography is the slope characteristics of land.
    • How do living organisms affect the soil?
      • Organisms living in the soil, like plants, insects and microbes actively affect soil formation.
      • Native Vegetation has
      • the greatest affect on
      • the development of
      • soil – plants that once
      • grew in it.
      • Two primary types
        • Tall grass prairie
        • Deciduous hard wood
        • forest
      • Prairie soils have a dark and deep surface layer. The roots of the prairie grass filled the top of the soil.
      • B. Timber soils tend to have a thin, moderately dark layer. Due to organic matter accumulating on the surface and decaying quickly.
    • Weathering
      • Physical weathering
        • The affects of climatic factors such as temperature, water, and wind. Freezing and thawing are a major contributor.
    • Weathing (cont.)
      • 2. Chemical weathering
      • a. changes the chemical makeup of rock and breaks it down. Rainwater can dissolve minerals.
      • b. Some minerals react with oxygen. Oxidation further decomposes rock.
    • Weathering (cont.)
      • B. Weathering causes soil to:
      • 1. Develop
      • 2. Mature
      • 3. Age
    • Climate
      • Refers to rainfall, freezing, thawing, wind, and sunlight.
    • Climate (cont)
      • B. The climate in Illinois is said to be of the continental type.
      • Hot Summers, Cold Winter
    • Climate (cont.)
      • C. Rainfall and Wind wear the rock away a little at a time.
    • Physical Features of soil
      • Soils have many features that are used to recognize the difference between them. They include:
      • A. Texture – coarseness of fineness of soil particles
      • B. Structure – the way in which soil particles are held together
      • C. Depth of horizons – depth of each soil
      • D. Color – darkness or lightness of soil color
    • Colors
      • Very Dark - ~5% O.M.
      • Dark - ~ 3.5% O.M.
      • Moderately Dark - ~ 2.5% O.M.
      • Light - ~2% O.M.
      • Very Light - ~1.5% O.M.
    • Soil Texture
      • Soil Texture is the fineness or coarseness of a soil.
        • Sand – largest particle
        • Silt – medium sized particle
        • Clay – small particle
      Sand Silt Clay
    •  
    • Texture (cont.)
      • B. Texture is important because it affects:
      • 1. Water holding capacity – the ability of a soil to retain water for use.
      • 2. Permeability – ease with which air & water my pass through the soil.
      • 3. Soil Workability – the ease with which soil may be tilled and amount of time after rain.
      • 4. Ability for plants to grow, ie carrots
    • Texture (cont.)
      • Soil texture may be determined in 2 ways
        • 1. Using a textural triangle. This is found be using the percentage of each type of soil particle.
    • Textural Triangle
    • Ribbon Method
      • Fine textured
      • Moderately fine textured
      • Medium textured
      • Moderately coarse
      • Coarse
    • Ribbon testing Ball of clay made in fist Starting to form a ribbon Clay Ribbon (>2&quot;) Starting to make a ribbon from sand Ribbons are hard to form with sand (<1&quot;)
    • Soil Structures
      • Granular
      • Crumb
      • Platy
      • Prismatic or Columnar
      • Blocky
      • Structureless
        • Single grain
        • Massive
    • Soil Structure
    • Soil Structure
    • Soil Structure
    • Soil Structure
    • Soil Structure
    • Soil Structure
    • Soil Structure
    •  
    • Soil Profile
      • A soil profile is a vertical cross section of soil.
        • Each layer may be different
        • A soil profile is usually studied to a depth of 3 to 5 feet.
    • Soil Profile
    • Changes in soil
      • II. Soils change over time in response to their environment.
      • A. The causes can be classified as:
      • 1. Additions
      • 2. Losses
      • 3. Translocation
      • 4. Transformation
    • Soil Degradation
      • Soil Degradation is lowering the quality of soil or loss of productivity. Occurs because people don’t understand the soil and consequences of its uses.
      • Results from:
        • Construction
        • Contamination
        • Erosion
    • Construction
      • Construction is altering land by building:
        • Roads
        • Houses
        • Offices
        • Factories
        • Other Structures
    •  
    • Contamination
      • Results when chemicals, oil, and other substances leak into the land.
      • D. Soil may be contaminated by Ag practices:
      • 1. Too much fertilizer
      • 2. Excess chemicals
      • 3. Irrigation water contains salt
    • Soil Erosion
      • IV. Soil erosion is the process by which soil is moved.
      • A. Natural causes (natural erosion)
      • 1. Round off mountains, fills in valleys
      • Ex. Mississippi Delta
      • B. Human actions
      • 1. Human activity, such as construction & plowing may cause accelerated erosion
      • a. removes topsoil at an excessive rate
    • Natural Erosion
    • Human actions accelerating
    • Soil Erosion
    • V. Other Sources
      • Improper irrigation practices
        • Salinization – accumulation of salts
        • Alkalinzation – accumulation of sodium
        • Waterlogging – supersaturation
      • Not replacing plant nutrients
      • Pollution
      • Overgrazing, deforestation, desertification
      • Compaction
    •  
    • Summary
      • Soil can be very fragile
      • Care must be taken to produce crops
      • Takes many, many years, to make new soil through weathering (1” > 1000 years)