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Soil Organic Matter

Unit: Soil Science Lesson 3

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Objectives

  • Define: soil organic matter
  • Explain the role of inherent factors affecting soil organic matter
  • Explain the five soil organic matter management practices
  • Explain how soil organic matter relates to soil function
  • Estimate organic material needed to increase soil organic matter
  • Measure soil organic matter

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Soil Organic Matter

  • Is the organic component of soil, consisting of three parts:
    • Plant residues and small living soil organisms
    • Actively decomposing matter
    • Humus: Stable organic matter

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Role of Inherent Factors Affecting Soil Organic Matter

  • Climate
    • Organic matter decomposes more quickly in warm and humid climates that cool dry climates
  • Soil Texture
    • Soil aeration: more oxygen in the soil speeds up the decomposition process
  • Vegetation
    • Prairie soils have more organic material added to the soil than forest soils because of vegetation.

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Soil Organic Matter Management

  • Use of cropping systems
  • Reducing or eliminating tillage
  • Reduce erosion
  • Soil-test and fertilize properly
  • Use of perennial forages

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Benefits of Soil Organic Matter

  • Nutrient Supply
  • Water-Holding Capacity
  • Soil Aggregation
  • Erosion Prevention