G nitrosomonas nitrobacter nitrogen xation by non

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Unformatted text preview: cation nitrifying bacteria, aerobes (e.g., Nitrosomonas, Nitrobacter) Nitrogen fixation by non-human processes: - terrestrial - marine - lightning by human processes: - crops (alfalfa, soybean, peanut) - industrial - fossil fuels shade-grown coffee: Erythrina trees & Rhizobium Phosphorus cycle in contrast with C & N, very small atmospheric reservoir weathering terrestrial sedimentary rock organisms: by aquatic plants & terrestrial plants (uptake by mycorrhizae) soils rivers & ocean marine sediments & sedimentary rock (largest reservoir) Mycorrhizae enhance plant’s ability to extract less soluble nutrients from soil Nutrient cycling: terrestrial vs aquatic ecosystems Terrestrial ecosystems Aquatic ecosystems decomposition rapid; mainly aerobic decomposition slower; often anaerobic “regeneration” takes place close to plant roots, where nutrients are assimilated “regeneration” takes place in sediment; assimilation takes place in photic zone => high productivity only... ... if sediment close to photic zone ... if transported to photic zone (lake mixing, upwellings) Human influence on nutrient cycles Carbon to: long-term reservoir atmosphere (air) long-term reservoir (rock) ➡ from: Nitrogen Phosphorus ➡ ➡ atmosphere organisms, soil, water organisms, soil, water...
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