Steam-distilled volatile oil from Artemisia ajira Jacq. (family Compositae), indigenous to the mountainous regions in southern Africa and used in popular medicine, was analysed by gas chromatography and tested for antimicrobial and antioxidative properties. The main components of the volatile oil were a-and /I-thujone (52%), 1,8-cineole (13 "/,), camphor (15 %) and a-pinene (2 %). Twenty-five bacterial species and three filamentous fungi were used to assess the antimicrobial properties. Fifteen test bacteria and one fungus showed high degree of inhibition of growth caused by the volatile oil. The most susceptible organisms were Acinetobacter calcoaceficus, Beneckea nafriegens, Breuibacferium linens, Brochothrix fhermosphacta, Citrobacter jiieundii, Klebsiella pneumoniae and Serratia marcescens. The oil exerted considerable antioxidative effect.

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Incubation and greenhouse studies showed that regardless of soil pH, flooding increased the content of exchangeable Mn and the Mn content of alfalfa (Medicago sativa L.) grown in a Kellner loamy sand. In the absence of a source of easily decomposable organic matter, Mn mobilization by flooding was considerably slower at a soil pH of 4.7 than at 7.3. Where alfalfa was grown in the soil or where finely milled oat straw was added, flooding mobilized more Mn in the acid than in the neutral soils. Liming promoted immobilization of Mn on the resumption of normal soil moisture relations after flooding. Seventy-two hours of flooding increased the Mn content of the alfalfa on the unlimed soil from 426 ppm to more than 6,000 ppm. Excess Mn tended to accumulate in the leaves and growing points of the plants. The results suggest that the well-known susceptibility of alfalfa to Mn toxicity may also account for its sensitivity to poorly aerated soils.

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