International Journal of Recycling of Organic Waste in Agriculture (IJROWA) Changes on microbial C and enzyme activities in soil with amendment of composted tannery sludge after 9 years Volume 8 (2019) Issue 4, December 2019- Supplements 2024 01 18 Changes on microbial C and enzyme activities in soil with amendment of composted tannery sludge after 9 years 10.1007/s40093-019-00296-6 EN Antonio Victor Cavalcante Rocha Silva Soil Quality Lab., Agricultural Science Center, Federal University of Piauí, Teresina, PI, 64049-550, Brazil Francisco Barbosa De Macedo Junior Soil Quality Lab., Agricultural Science Center, Federal University of Piauí, Teresina, PI, 64049-550, Brazil Jadson Emanuel Lopes Antunes Soil Quality Lab., Agricultural Science Center, Federal University of Piauí, Teresina, PI, 64049-550, Brazil João Pedro Alves De Aquino Soil Quality Lab., Agricultural Science Center, Federal University of Piauí, Teresina, PI, 64049-550, Brazil Regina Maria Silva Sousa Soil Quality Lab., Agricultural Science Center, Federal University of Piauí, Teresina, PI, 64049-550, Brazil Louise Melo De Souza Oliveira Soil Quality Lab., Agricultural Science Center, Federal University of Piauí, Teresina, PI, 64049-550, Brazil Ademir Sérgio Ferreira De Araujo Soil Quality Lab., Agricultural Science Center, Federal University of Piauí, Teresina, PI, 64049-550, Brazil Journal Article 2024 01 18 Purpose The consecutive amendment of composted tannery sludge (CTS) could promote changes in the status of soil microorganisms. Thus, this study evaluated the changes on microbial C and enzyme activities in soil after 9 years of CTS amendment. Methods CTS was amended from 2009 to 2018 at five rates: 0, 2.5, 5, 10, and 20 ton ha−1. In 2018, the soil chemical properties (pH, electric conductivity, P, K, Cr, and total organic C), microbial C and enzyme activities were evaluated after 30 days from the amendment. Results The values of chemical properties increased after nine years of CTS application. The content of microbial C and the enzyme activities increased with the amendment of 2.5 and 5 ton ha−1, and decreased with the amendment of10 and 20 ton ha−1. Conclusion This study showed that the amendment of10 and 20 ton ha−1 of CTS increased soil pH and Cr concentration and promoted a decreasing on soil microbial C and enzyme activities.