Response of Eisenia fetida to the application of different organic wastes in an aluminium-contaminated soil.

Abstract

The effects of amending Al-contaminated soils with municipal solid waste compost (MSW), poultry manure (PM) and cow manure (CM) on Al toxicity and morphological alterations and biochemical enzymes of the earthworm Eisenia fetida were investigated in an incubation spiking experiment. Al(NO(3))(3) was added to a soil at rates equivalent to 0, 50 and 100 mg Al kg(-1). In order to apply the same amount of organic matter (OM), soil samples were mixed with MSW, PM and CM at a rate of 10%, 7.6% and 5.8%, respectively. Earthworm cocoon number, average weight of cocoon and number of juveniles per cocoon were measured after 30 days of incubation, whereas weight, Al concentration and available Al, as well cellulase and glutathione-S-transferase activities of earthworms were measured after 3, 15, 30, 60, 90 and 120 days. Reproductive and enzymatic activities of earthworms decreased with increasing the rate of Al applied. The inhibition of weight, enzyme activities and Al concentration of earthworm was lower in organically amended soils than in unamended soils. At the end of the incubation, earthworm weight and enzymatic activities in highly contaminated soils increased and Al concentration in earthworm tissues decreased as the relative amount of humic acids applied to soil increased, following the order unamended soil<CM-amended soil<PM-amended soil<MSW-amended soil. These results suggest that the application of organic amendments with higher content of humic acids may be more beneficial for remediation of Al-polluted soils.