PLSC204 Lecture 25: Soil organic matter
4 Feb 2019
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Document Summary
Soil holds double vegetation and atmosphere put together. Breakdown of large om into smaller simpler components. When organic tissue is added to aerobic soil , three reactions take place. Enzymatic oxidation of carbon compounds to produce carbon dioxide, water, energy, and decomposer biomass. Release and/or immobilization of the essential nutrient elements, such as nitrogen, phosphorus, and sulfur, by a series of specific reactions that are relatively unique for each element. Formation of compounds very resistant to microbial action, either through modification of compounds in the original tissue or by microbial synthesis. Added organic matter provides needed nutrients for biomax and energy production - nutrients vary with residue composition. Polymers (celluloses, proteins, starch, dna, ligins) -> monomeric units (sugars, amino acids, phenols) -> mineralization for carbon, energy and nutrients. Steps 1 and 2 happen outside of microbial cells via release of extracellular enzymes. Plant benefits from steps 2 going to step 3. Organic matter added to a soil creates a response.
