Enzymatic Activity of a Mine Soil Varies According to Vegetation Cover and Level of Compost Applied

We applied three doses of compost from mixed municipal solid waste (0, 15, and 30 g kg-1 of soil) to a soil developed on pyrite mine wastes. Part of the soil was planted with young Erica australis L. collected at the mine; part was fertilized with N-P-K-Mg and sown with Dactylis glomerata L. Bare soil without mineral fertilization was included in the experiment, as well. Compost application to bare soil increased pH, provided plant nutrients, and enhanced the activity of the six soil enzymes tested. Growth of D.glomerata, and E. australis was stimulated in compost-amended soil compared with unamended controls. The presence of D.glomerata led to the greatest activities of soil acid phosphatase, -glucosidase, and cellulase compared with bare soil or with soil with E. australis. The presence of E. australis increased the activities of protease and cellulase in amended soil, compared with control, but it impaired dehydrogenase, -glucosidase, and acid phosphatase activities. These negative impacts probably derived from phenolic compounds known to be released from roots of this species. The survival strategy of this species seems to include a small need for P in the shoots, and the release of exudates that impair microbial activity and P cycling.