Organic Matter in the Soil

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Organic Matter in the Soil
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• Waste is a human concept. In nature nothing is
  wasted, for everything is part of a continuous
  cycle. Even the death of a creature provides
  nutrients that will eventually be reincorporated
  in the chain of life.
• Denis Hayes

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What is Organic Matter?

• all plant and animal residues in the soil

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What things make up soil organic matter?

• Plant animal residues
• Barnyard manure
• Green manure
• Dead roots
• Insect worm carcasses excrement
• Dead soil micro-organisms (bacteria, fungi,
  protozoa)

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What is Green Manure?

• a crop grown for its organic matter
• green manure crops are generally plowed under
  while they are still green
• Examples sweet clover, rye

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What two things have greatly lowered the Organic
Matter content of soil?

• soil erosion
• continuous cropping

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How can organic matter be increased?

• crop residues
• barnyard manure
• green manure

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What is the difference between organic matter
humus?

• Organic matter is dead plant animal life before
  it has been broken down
• Humus relative stable product of the
  decomposition of organic matter

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What is Mineralization?

• organic matter is broken down into simple mineral
  compounds
• Due to the action of bacteria fungi

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When organic matter breaks down, what is released
for the crop's use?

• Nutrients (sulfur, nitrogen, phosphorous,
  potassium, calcium, magnesium micronutrients)

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How does Organic Matter Improve Soil?

• 1) increase water holding capacity
• 2) nutrients attach to O.M.
• 3) O.M. improves tilth (aggregate)
• 4) The amount of humus in soil is directly
  proportional to the amount of nitrogen in soil

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How does Organic Matter Improve Soil?

• 5) Soils high in O.M. are easily worked and may
  be described as having good tilth.
• 6) Improves soil structure
• 7) Improves aeration

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Benefits of Organic Matter

• Organic Matter promotes granulation of soil by
  binding soil particles into granules.
• O.M. makes clay soils less sticky and improve
  tilth.
• Deeper root growth and water entry and storage
  are improved as well as aeration of the soil.

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Organic Matter Sandy Soils

• Sandy soils have good aeration but dry out
  quickly. Sandy soils increase water holding
  capacity and have less erosion as O.M. is added?

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What is the largest source of O.M. in the soil?

• plant roots

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Which is the most preferred green manure, legumes
or non-legumes?

• legumes- added nitrogen

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What is nitrogen tie-up?

• microorganisms in the soil use the nitrogen in
  the soil to break down organic matter, thus it is
  temporarily "tied up" (used as food)
• this is very important when considering
  re-cropping and not allowing the soil to have a
  year in fallow to allow for mineralization in
  order to reduce the nitrogen tie-up.

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Is organic matter a good mulch?

• Yes
• Reduces surface evaporation
• Equalizes soil temperature
• Increases soil animal life
• Reduces soil erosion

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Detrimental effects of soil organic matter

• Energy source for many disease organisms
  ensuring their survival in the soil
• Excessive amounts of plant residues are difficult
  to incorporate into the soil and hinder some
  planting operations
• Addition of organic matter into soil may
  temporarily increase the carbonnitrogen ratio
  thus limiting the available nitrogen to the
  current crop

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How many square feet are in an acre?

• 43,560

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What is an acre-six inches?

• six inches of soil over an acre

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An acre-six inches weighs how many pounds?

• 2 million

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Soil Conservation

• A typical farmer is doing a "good job" of soil
  conservation if he loses less than 1/16" of
  topsoil each year. How many pounds of soil does
  he/she lose each year if he/she loses 1/16"? How
  many tons? (extra credit)

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How long does it take to create soil?

• It takes 100 to 400 years to create 1" of topsoil.