Ammonia evolution and urease, phosphatase and protease activities were measured after field incubations of soil from 5 sites, differently influenced by penguin guano, from Cape Bird, Antarctica. Rates of NH3production were low considering the large amounts of free NH3in these soils. Enzyme activities were higher than expected and, under optimum conditions of temperature, moisture and substrate availability, were sufficient to degrade rapidly the accumulated organic matter in these soils. Laboratory incubations confirmed these high levels of activity; they also showed high dehydrogenase, but not sulphatase, activity. The surface horizon from the site that received continuous additions of fresh penguin excreta had considerably more enzyme activity than the other samples. The optimum activity of phosphatase in this sample was at pH 9.5-10. These enzyme activities are compared with those of New Zealand topsoils, and considered in relation to activities likely to occur under field conditions. Recommendations are made for further biochemical studies at Cape Bird.
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