Composition of organic solutes and respiration in soils derived from alkaline and non-alkaline parent materials

• Published in: Geoderma Vol. 144; no. 3; pp. 468 - 477
• Main Authors: Nambu, K., van Hees, P.A.W., Jones, D.L., Vinogradoff, S., Lundström, U.S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.04.2008; Elsevier
• Subjects: Acidity; Agronomy. Soil science and plant productions; Biological and medical sciences; Calcium; Chemistry; DOC; Earth sciences; Earth, ocean, space; Environmental chemistry; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Geochemistry; Kemi; Microbial activity; Miljökemi; NATURAL SCIENCES; NATURVETENSKAP; Organic acids; Soil and rock geochemistry; Soils; Surficial geology; pH; Microbial activity; DOC; Acidity; Calcium; Organic acids; minerals; oxalates; soil parent materials; Available nutrient; Citrate; calcite; respiration; Glucose; Inorganic element; organic acids; Dissolved organic carbon; Soil solution; solutes; calcium; Radiolabelling; concentration; organic minerals; Nutrient uptake; carbonates; Rhizosphere; Alkaline soil; acidity; microorganisms; pedogenesis; Phenols
• ISSN: 0016-7061; 1872-6259; 1872-6259
• DOI: 10.1016/j.geoderma.2007.12.014

Parent material greatly influences pedogenesis and soil nutrient availability and consequently we hypothesized that it would significantly affect the amount of organic solutes in soil, many of which have been implicated in rhizosphere processes linked to plant nutrient uptake. Consequently, we investigated the influence of two contrasting parent materials in which calcite was present or absent (alkaline and non-alkaline soils) on the concentrations of dissolved organic carbon (DOC), low-molecular weight organic acids (LMWOA) and glucose in soil solution. Both soils were under Norway spruce. The dynamics of LMWOAs in soil were also investigated using 14C-labelled citrate and oxalate. Some of the mineral horizons of the alkaline soils showed significantly higher concentrations of DOC, phenolics, and fumarate in soil solution and also a higher basal respiration. No major differences were seen in organic solute status in the organic horizons of the two soil types. LMWOAs were present at low concentrations in soil solution (< 1 to 25 µM). Their mineralization rate significantly decreased with soil depth, however, overall neither their concentration or half-life in soil was markedly affected by parent material. The alkaline soils had significantly higher CO 2-to-soil organic C (SOC) ratios, and consequently SOC in the alkaline soils did not seem more chemically stable against mineralization. Considering possible DOC and CO 2 efflux rates it was suggested that the equal or larger SOC stocks in alkaline mineral soils were most likely linked to a higher net primary productivity. In conclusion, our study found that parent material exerted only a small effect on the concentration and dynamics of organic solutes in soil solution. This suggests that in comparison to other factors (e.g. vegetation cover, climate etc) parent material may not be a major regulator of the organic solute pool in soil.