EESB05H3 Lecture Notes - Nitrogenase, Natural Abundance, Tillage
9 Dec 2013
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Document Summary
Organisms in the soil are highly abundant and diverse. Fauna is used to distinguish animals from flora (refers to the true plant and non-animal microorganisms) Macrofauna (>2mm) - all heterotrophs, largely herbivores and detritivores. Mesofauna (0. 1-2mm) - all heterotrophs, largely detritivores, and predators. Microfauna (<0. 1mm) - detritivores, predators, fungivores, and bacterivores. Controlled by supply of decomposable organic matter. Mostly heterotrophic, use organic matter and carbon as energy. Decomposition of plant residues is an oxidative process. Soil organic matter is a complex and varied mixture of organic substances; all organic readily decomposable substances breakdown first, leaving more resistant humus matter contains carbon rapid litter breakdown leads to rapid nutrient cycling. Organic matter decay contribute to net co2 atmospheric release. Soils play a central role in the global carbon cycle, both as a carbon repository, sink, and source. Plants take in carbon dioxide from the atmosphere through photosynthesis, the energy of sunlight is trapped in the carbon-carbon bonds of organic molecules.
