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The Threshold Moisture Content for Active Decomposition of Some Mature Plant Materials
Author(s) -
Bartholomew W. V.,
Norman A. G.
Publication year - 1947
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1947.036159950011000c0052x
Subject(s) - soil water , agriculture , citation , library science , agricultural experiment station , water content , political science , engineering , environmental science , archaeology , geography , computer science , soil science , geotechnical engineering
'"Tp HE range of moisture and temperature within 1 which aerobic soil microorganisms are capable of activity is rather wide. The rate of activity, however, within this range is not uniform. Each species has an optimum range of moisture and temperature in which its activities are most rapid. As either the moisture or the temperature deviates from this optimum, the activities of the organisms are reduced. As the temperature rises above the optimum the organisms are first reduced in activity and then ultimately killed. Because the activities of microorganisms are carried on within a water film, increase in moisture content -above the optimum has little effect until anaerobic conditions have developed. On the other hand, reducing the moisture content ot substrates below the optimum tends to reduce the extent and rate of decomposition accomplished by the microorganisms and at low moisture contents, the organisms are reduced to inactivity and may even die. Reduced temperature has a similar effect in that the organisms are rendered incapable of normal activity. This principle' of arrested microbiological activity at low moisture and temperature is important in regulating or influencing a number of natural biological processes and has found application in the solution of many practical problems of storage and preservation of plant and animal products. The rate of decomposition of crop residues, manures, and soil organic matter is chiefly influenced by the moisture and temperature factors. The low organic matter content of soils in climates characterized by moderately high mean annual temperatures and high, well-distributed rainfall is evidence of this fact.