Abstract |
Tannery sludge was compared with commercial nitrogen fertiliser to investigate its potential use as an alternative to commercial fertiliser. Soils containing 38% and 7% organic carbon and with nitrogen contents of 1-3% and 0-2%, respectively, were amended with either commercial N fertiliser or tannery sludge which contained 1-6% chromium. Part of the tannery waste was supplemented with additional chromium (Cr(+3)) salt before being added to the soils. Tall fescue, bush bean, and maize were grown in the sludge-treated soils and their tops harvested. First harvest yields of dry matter increased when tannery sludge was added to the soil, although less than with commercial N addition. Yields from subsequent harvests were larger from soils amended with tannery sludge. Yields of bush beans, maize, and tall fescue will increase when tannery sludge is added to soils; however, benefits of the sludge will depend upon: (1) nitrogen status of the soil; (2) organic content of the soil; (3) salt and Cr content of the tannery waste; (4) plant species; and (5) soil pH reaction. |