BIOMASS CARBON MEASUREMENTS AND SUBSTRATE UTILIZATION PATTERNS OF MICROBIAL-POPULATIONS FROM SOILS AMENDED WITH CADMIUM, COPPER, OR ZINC

Samples of a sandy loam soil taken from a long-term liming experiment in southeast England were amended with solutions of metal sulfate salt s, Soils with a range of pHs were amended to contain Cu, Cd, or Zn at concentrations around the maximum permissible values for these metals in agricultural land receiving sewage sludge, After a 3-year equilibra tion period, the microbial biomass was determined by the fumigation-ex traction technique, These results were compared with data from substra te utilization patterns of microbial populations extracted by using a weak salt solution, There was no reduction in microbial biomass due to pH or metal treatment in any of the soils except the Cu treatment, Pr incipal-component analysis of the respiration patterns in Biolog plate s demonstrated effects of both pH and metal treatment on the extracted microbial population which were independent of gross biomass size, pH and soil amendments with Cu and Zn were found to reduce the metabolic potential of the extracted soil microbial population.