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AEROBIC AND ANAEROBIC SOIL MICROBIAL ACTIVITY AS INFLUENCED BY TILLAGE AND SOIL PHYSICAL PROPERTIES
Abstract
Numbers and activities of microorganisms in no-till and conventionally tilled (plowed) soils were strongly influenced by the percentage of soil pore space filled with water (WFP). Under laboratory conditions, soil water contents equivalent to 60% WFP provided conditions favorable for optimum aerobic microbial activity, however, percent WFP greater than 60% favored anaerobic microbial activity. Under field conditions, greater soil bulk densities (lower total soil porosity) combined with the greater soil water contents of surface (0-75 mm) no-till soils at several U.S. locations resulted in greater WFP values than those of adjacent plowed soils. Average WFP of these surface soils (0-75 mm) were 54.4% with no tillage compared to 42.9% with plowing. Carbon dioxide (CO(,2)) and nitrous oxide (N(,2)O) production from surface 0-75 mm no-till soils reflected the greater WFP of these soils with 24-h CO(,2) and N(,2)O values averaging 3.7 and 9.4 times greater, respectively, than from plowed soils. Numbers of aerobic and anaerobic microorganisms, N(,2)O production following acetylene blockage (denitrification potential), and dehydrogenase activity were also greater from surface 0-75 mm no-till soils in comparison to plowed soils. Below 75 mm, WFP in plowed soils averaged close to 60% whereas in no-till soils this value was often exceeded. Accordingly, CO(,2) production and aerobic microbial numbers at 75-150 mm in plowed soils increased with respect to surface values. Under no tillage, CO(,2) production and aerobic microbial numbers at 75-150 mm decreased from the surface values. Numbers of anaerobic microorganisms in plowed soils also increased at 75-150 mm, however, numbers of these organisms under no tillage remained close to those in the surface 0-75 mm. As a result, no significant difference in anaerobic microbial numbers occurred between tillage treatments at 75-150 mm, as was also the case for denitrification and dehydrogenase activity. These observations indicate the presence of a less-oxidative environment in no-till surface soils and a greater potential for denitrification and biological immobilization of plant available nitrogen compared with plowed surface soils. Development to techniques designed to improve the efficient use of nitrogen fertilizer with the no-till system appear justified.
Subject Area
Agronomy
Recommended Citation
LINN, DANIEL MYRON, "AEROBIC AND ANAEROBIC SOIL MICROBIAL ACTIVITY AS INFLUENCED BY TILLAGE AND SOIL PHYSICAL PROPERTIES" (1982). ETD collection for University of Nebraska-Lincoln. AAI8306490.
https://digitalcommons.unl.edu/dissertations/AAI8306490