title: Soil microbial properties after 5 years of consecutive amendment with composted tannery sludge.
abstract: Composting has been recognised an alternative method to tannery sludge recycling and afterwards to be used in agriculture. As the tannery sludge contains salts and chromium, the application of composted tannery sludge (CTS) should be performed carefully to minimise negative effects on soil microbial properties. Therefore, this study evaluated the effects of 5-year repeated CTS amendment on soil microbial biomass (SMB) and enzyme activities in a tropical soil. CTS was applied during 5 years at 0, 2.5, 5, 10 and 20 Mg ha(-1), and at the fifth year, the microbial biomass C (MBC) and N (MBN), basal and substrate-induced respiration (SIR), metabolic quotient (qCO₂) and dehydrogenase (DHA) and fluorescein diacetate (FDA) hydrolysis were determined in the soil samples. Soil MBC and MBN showed the highest values with the amendment of 5 Mg ha(-1) CTS. Soil respiration increased with the increase in CTS rates, while SIR showed the highest values with the amendment of 0, 2.5 and 5 Mg ha(-1) CTS. DHA activity showed the highest values with the amendment up to 2.5 Mg ha(-1), while FDA hydrolysis increased up to the rate of 5 Mg ha(-1) CTS. The results show that after 5 years of permanent amendment of CTS, soils amended with 2.5 Mg ha(-1) have SMB and enzymatic activities similar to those in unamended soil.
authors.affiliation: Soil Quality Lab., Agricultural Science Center, Federal University of Piauí, Teresina, PI, Brazil, asfaruaj@yahoo.com.br.
authors.forename: Ademir Sérgio Ferreira
authors.initials: AS
authors.lastname: Araujo
authors.forename: Ana Roberta Lima
authors.initials: AR
authors.lastname: Miranda
authors.forename: Mara Lucia Jacinto
authors.initials: ML
authors.lastname: Oliveira
authors.forename: Vilma Maria
authors.initials: VM
authors.lastname: Santos
authors.forename: Luís Alfredo Pinheiro Leal
authors.initials: LA
authors.lastname: Nunes
authors.forename: Wanderley José
authors.initials: WJ
authors.lastname: Melo
mesh_terms: D000383:Agriculture; D018533:Biomass; D004784:Environmental Monitoring; D012722:Sewage / Q000382:microbiology*; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis*; D013633:Tanning; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D012722:Sewage; D012987:Soil; D012989:Soil Pollutants