Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2006
Abstract
No abstract has been registered
2005
Abstract
Considerable knowledge exists about the effect of aluminium (Al) on root vitality, but whether elevated levels of Al affect soil microorganisms is largely unknown. We thus compared soils from Al-treated and control plots of a field experiment with respect to microbial and chemical parameters, as well as root growth and vitality. Soil from a field experiment established in a 50 year old Norway spruce (Picea abies L.) stand where low concentrations of aluminum (0.5 mM AlCl3) had been added weekly or bi-weekly during the growth season for seven years was compared to a control treatment with respect to microbial and chemical parameters, as well as root growth and vitality. Analysis of soil solutions collected using zero tension lysimeters and porous suction cups showed that Al treatment lead to increased concentrations of Al, Ca and Mg and lower pH and [Ca+Mg]/[Al] molar ratio. Corresponding soil analyses showed that soil pH remained unaffected (pH 3.8), that Al increased, while extractable Ca and Mg decreased due to the Al treatment. Root ingrowth into cores placed in the upper 20 cm of the soil during 28 months was not affected by Al additions, neither was the mortality of these roots. The biomass of some taxonomical groups of soil microorganisms in the humus layer, analyzed using specific membrane components (phospholipid fatty acids; PLFAs), was clearly affected by the imposed Al treatment, but less so in the underlying mineral soil. Microbial community structure in the humus layer was also clearly modified by the Al treatment, whereas differences in the mineral horizon were less clear. Shifts in PLFA trans/cis ratios indicative of short term physiological stress were not observed. Yet, aluminium stress was indicated both by changes in community structure and in ratios of single PLFAs for treated/untreated plots. Thus, soil microorganisms were more sensitive indicators of subtle chemical changes in soil than chemical composition and vitality of roots.