EFFECT OF TANNERY SLUDGE ON THE CELLULOSE DECOMPOSITION IN THE SOIL

Abstract

The effect of tannery sludge on the cellulose decomposition was studied in the laboratory as a dose-response experiment. Cellulose decomposition rates were determined by the weight loss from cellulose filter disks buried in soil samples. The amount of tannery sludge used were 0, 11, 22, 44, 88 and 172 Mg ha-1, and, corresponded, respectively, to incorporation of 250, 500, 1,000, 2,000 and 4,000 mg Cr3+ kg-1 of soil. The cellulose filter disks presented different degrees of decomposition with application of tannery sludge. After 30 days of incubation the cellulose decomposition rate, corresponding to application of 11, 22 and 44 Mg ha-1 were higher than soil untreated (control), respectively 5%, 20% and 10%, but the difference was only significant for the 22 Mg ha-1. There was a significant decrease of 50% in the cellulose decomposition, compared to untreated soil (control), with application of 172 Mg ha-1 of tannery sludge. This study has demonstrated that cellulolytic activities are susceptible to be inhibited by high rates of tannery sludge. When applied to low amounts, tannery sludge did not affect cellulose decomposition by the soil microflora.