Biochemical changes in a yellow-brown loam and a central gley soil converted from pasture to maize in the Waikato area

Cairns, Annetie

doi:10.1080/00288233.1982.10423370

Cited by 22 publications

(1 citation statement)

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“…In allophanic soils, organic matter reacts slowly with allophane, and the formation of organicallophane complexes causes organic matter to decompose more slowly than in other soils. In allophanic soils enzymatic activities per unit of organic carbon are less than in other soils (Ross et al, 1982). Mulder et al (2001) showed that increasing the concentration of Al in the forest oor caused a 30-40% decrease in the decomposition rate of soil organic matter.…”

Section: Introductionmentioning

confidence: 99%

The effects of Fe- and Mn-oxides and imogolite in the presence of kaolinite on organic nitrogen mineralization and soil enzyme activities

Rakhsh

Golchin

Nelson

et al. 2023

Archives of Agronomy and Soil Science

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Clay minerals and metal oxides play an important role in controlling the decomposition of soil organic matter and the mineralization of organic nitrogen. To study the effects of clay content and composition on mineralization of organic nitrogen, an incubation experiment was carried out. In the experiment, mineralization of organic nitrogen from alfalfa residues, activities of acid and alkaline phosphatase and CM-cellulase, and microbial biomass nitrogen were measured in mixtures of sand, kaolinite (0, 15, 30 or 45%) and non-layered colloids (NLCs, being goethite, manganese oxide or imogolite at a kaolinite:NLC ratio of 1:0, 5:1 or 10:1), with pure sand as the control, which were inoculated with microbes from natural soil and incubated at 23°C in the dark at 60% of water holding capacity for 180 days. Mineralization of organic nitrogen and enzyme activity decreased, but microbial biomass nitrogen increased as the contents of kaolinite and NLCs increased. There was an inverse relationship between the speci c surface area of the mixtures and the enzyme activity and mineralization of organic nitrogen. Thus, the decreased mineralization of organic nitrogen, despite an increase in microbial biomass, appears to have been due to inactivation of extracellular enzymes by adsorption to the surfaces of kaolinite and NLCs, and perhaps also decreased accessibility of organic nitrogen substrate molecules due to adsorption. The microbial biomass nitrogen increased as the water holding capacity of the mixtures increased, indicating the importance of water-lled pores for accommodating an active microbial biomass and protecting it from desiccation and predators.

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Section: Introductionmentioning

confidence: 99%