Soil microbial activity as an indicator of soil fertility : the long-term effects of municipal sewage sludge on an arid soil (MS)
AuthorBrendecke, Jeffrey Walter.
Soil microbial ecology.
Committee ChairPepper, Ian L.
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PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractThis study measured the effects of four years of municipal, anaerobically digested sewage sludge application on long-term soil microbial activity in a Pima clay loam (Typic Torrifluvent) growing Upland cotton (Gossypium hirsutum L.). Treatments were one unfertilized control, sludge applied at optimum rates for plant growth (based on N requirements), and sludge applied at three times the optimum rates (a total of 8.01 and 24.2 Mg ha⁻¹ (dry weight over four years)). Soil microbial activity was measured by viable heterotrophic plate counts for bacteria, actinomycetes and fungi; acridine orange direct counts for bacteria; the dehydrogenase assay; and carbon dioxide evolution analysis. As the high sludge treatment significantly reduced cotton plant stand and significantly stimulated some parameters of microbial activity (dehydrogenase activity and CO₂ evolution), soil microbial activity may not serve as a reliable predictive index of plant response to sludge-applied pollutants.
Degree ProgramSoil and Water Science