The effects of Fe- and Mn-oxides and imogolite in the presence of kaolinite on organic nitrogen mineralization and soil enzyme activities
Journal Publication ResearchOnline@JCUAbstract
An incubation experiment was conducted to study the effect of clay content and composition on organic nitrogen mineralization. The experiment measured the mineralization of organic nitrogen from alfalfa residues, enzyme activities, and microbial biomass nitrogen in mixtures of sand, kaolinite, and non-layered colloids (NLCs) with sand as a control. The study found that as the contents of kaolinite and NLCs increased, the mineralization of organic nitrogen and enzyme activity decreased, but microbial biomass nitrogen increased. The maximum decrease in organic nitrogen mineralization was 88.6%, and microbial biomass nitrogen increased from 4.7 to 15.5%. The acid and alkaline phosphatase activities also decreased by 86.0 and 93.6%, respectively, with an increase in clay content. The specific surface area (SSA) of the mixtures showed an inverse relationship with enzyme activity and mineralization of organic nitrogen. Inactivation of extracellular enzymes by adsorption on the surfaces of kaolinite and NLCs, and decreased accessibility of organic nitrogen substrate molecules due to adsorption, reduced the mineralization of organic nitrogen. Microbial biomass nitrogen increased as the water holding capacity of the mixtures increased, indicating the importance of waterfilled pores in accommodating active microbial biomass and protecting it from desiccation and predators.
Journal
Archives of Agronomy and Soil Science
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N/A
Volume
69
ISBN/ISSN
1476-3567
Edition
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Issue
14
Pages Count
19
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N/A
Publisher
Taylor and Francis
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EISSN
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DOI
10.1080/03650340.2023.2210057