Federal University of Piauí
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 fve 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.