Soil microbial activity in relation to dissolved organic matter properties under different tree species

• Published in: Plant and soil 2014-04, Vol.377 (1-2), p.169-177
• Main Authors: Kiikkilä, Oili, Kanerva, Sanna, Kitunen, Veikko, Smolander, Aino
• Format: Article
• Language: English
• Subjects: Acid soils; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Betula; Biochemistry and biology; Biological and medical sciences; Biomass; Biomedical and Life Sciences; Chemical properties; Chemical, physicochemical, biochemical and biological properties; data collection; Decomposition; Dissolved organic carbon; Dissolved organic matter; Ecology; Forest soils; Fractionation; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Humus; Life Sciences; Microbial activity; microbial biomass; microbial growth; Microbiology; microorganisms; Mineral soils; Mineralization; molecular weight; multivariate analysis; Organic matter; Organic soils; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plant Physiology; Plant Sciences; Plant species; Plant-soil relationships; Regular Article; Slope stability; soil; Soil biochemistry; Soil microbiology; Soil microorganisms; Soil organic carbon; Soil organic matter; Soil research; Soil science; Soil Science & Conservation; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Soils; Trees
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-013-1988-2

BACKGROUND AND AIMS: The total concentration of dissolved organic carbon (DOC) has often been observed to correlate positively with soil microbial respiration. The aim was to explain the correlation with the properties of dissolved organic matter (DOM). METHODS: A dataset from previously published papers was gathered together and subjected to multivariate analyses. Samples were collected from five tree species experiments in Finland. The degradability of DOM was assessed by measuring bacterial and fungal growth in DOM. The chemical properties of DOM were assessed by XAD resin fractionation and molecular weight. Soil microbial activity was assessed as C and N mineralization and microbial biomass. RESULTS: Both low and high molecular weight compounds, as well as hydrophilic neutral compounds, seemed to be relatively easily degradable. In contrast to our presupposition, easily degradable DOM seemed to be less abundant in soil where variables describing microbial activity were higher. Birch soil with higher microbial biomass N seemed to contain less easily degradable DOM than spruce soil. CONCLUSION: We suggest that DOM collected and characterized at a certain point reflects more the accumulation of refractory compounds following high microbial activity than the easily degradable compounds that microbes would be using when measured.