UIUC NRES 201 - Soil Organisms and Ecology II (3 pages)

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Soil Organisms and Ecology II

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Soil Organisms and Ecology II


Lecture number:
Lecture Note
University of Illinois at Urbana, Champaign
Nres 201 - Introductory Soils
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NRES 201 Lecture 31 Outline of Last Lecture I The diversity of soil organisms II The food web III Organism abundance and metabolic activity Outline of Current Lecture IV Earthworms V Ants VI Termites VII Nematodes VIII Protozoa Current Lecture Earthworms The most important member of the soil micro fauna and the most beneficial for plant growth Known as nature s tillers because their burrowing actions loosen the soil They eat their way through the soil Bacteria are their main food Their manure improves soil fertility Soil and Environmental effects Burrows o Earthworms annually ingest 20 400 tons of soil per acre o Their burrows can be extensive particularly in the absence of tillage o Their burrows become channels for root growth Casts o Earthworm waste in the form of soil globules o These globules Are often deposited on the soil surface Consist of a mixture of organic and mineral matter Occur as stabilized aggregates Have a high content of nutrients and CaCO3 Other beneficial effects o Residue Incorporation Nearly eliminates thatch in turfgrass Helps conserve nutrients These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o Earthworm burrows reduce soil compaction and increase water infiltration aeration and drainage Deleterious effects o Exposure of surface soil nightcrawlers can increase erosion by leaving more than half the soil bare o Stimulation of nutrient cycling invading nightcrawlers have depleted the O horizon in boreal forests o Promotion of macropore leaching Vertical earthworm burrows can serve as a pathway for chemical transport to tile lines but absorption is increased by the organic lining in these burrows Factors affecting earthworm activity o Activity favored by Moist well aerated soils well supplied with organic residues or surface mulch Cool soil temperature in the spring or fall A good supply of soil Ca at pH 5 5 8 5 o Activity is depressed by

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