Repeated application of composted tannery sludge affects differently soil microbial biomass, enzymes activity, and ammonia-oxidizing organisms

Abstract

Repeated application of composted tannery sludge (CTS) changes the soil chemical properties and, consequently, can affect the soil microbial properties. The aim of this study was to evaluate the responses of soil microbial biomass and ammonia-oxidizing organisms to repeated application of CTS. CTS was applied repeatedly during 6 years, and, at the sixth year, the soil microbial biomass, enzymes activity, and ammonia-oxidizing organisms were determined in the soil. The treatments consisted of 0 (without CTS application), 2.5, 5, 10, and 20 t ha(-1) of CTS (dry basis). Soil pH, EC, SOC, total N, and Cr concentration increased with the increase in CTS rate. Soil microbial biomass did not change significantly with the amendment of 2.5 Mg ha(-1), while it decreased at the higher rates. Total and specific enzymes activity responded differently after CTS application. The abundance of bacteria did not change with the 2.5-Mg ha(-1) CTS treatment and decreased after this rate, while the abundance of archaea increased significantly with the 2.5-Mg ha(-1) CTS treatment. Repeated application of different CTS rates for 6 years had different effects on the soil microbial biomass and ammonia-oxidizing organisms as a response to changes in soil chemical properties.

Less abundant bacterial groups are more affected than the most abundant groups in composted tannery sludge-treated soil

“…As expected, previous studies have found a significant influence of the CTS on the chemical properties of soil 5 , and these changes have affected the soil microbial biomass and enzyme activities 1 . However, it is unclear how the CTS affects the bacterial community over time, i.e., what the time-dependent effects of CTS are on the bacterial community and structure.…”

“…Specifically, tannery industries have released annually high amounts of tannery sludge (TS), a type of solid waste that contains large amounts of chromium (Cr), salts, carbonates, and hydroxides 1 . Although it is well-known that TS transfers these chemical elements, this has not precluded its use as a soil conditioner in agriculture 2 , 3 .…”

“…Currently, new methods to detoxify TS before its use have been proposed, and composting has been reported to be an efficient method 1 . The use of composted tannery sludge (CTS) has improved the soil organic matter content and concentrations of plant nutrients, such as P, K, and Ca 1 , 5 . However, the permanent amendment of CTS has promoted the accumulation of Cr and can cause soil pollution 5 .…”

Dynamics of archaeal community in soil with application of composted tannery sludge

“…The overall significance of the CTS treatment regime on the variation in OTU (p ≤ 0.05) was tested by performing 999 Monte Carlo permutations 53 . The NOECs of the tannery sludge treatment per sampling date was calculated by applying the Williams test 54 to the sample scores of the first principal component of each sampling date 53 , using the Community Analysis computer program, version 4.3.05 55 using a significance level of 0.05 56 .…”

<b>Chromium accumulation in maize and cowpea after successive applications of composted tannery sludge

“…Some studies have proposed the agricultural use of composted tannery sludge as an alternative treatment method like that of other similar solid waste (Singh et al, 2015;Singh, Singh, Ibrahim, & Hashim, 2011;Silva et al, 2010). Previous studies have shown that the use of composted tannery sludge has improved the soil fertility and crop yield (Miranda, Nunes, Oliveira, Melo, & Araújo, 2014;Araújo, Lima, Santos, & Schmidt, 2016). On the other hand, the application of composted tannery sludge has been reported to increase the Cr concentrations in the soil (Santos, Araújo, Nunes, Oliveira, & Melo, 2014), which could limit its use for agricultural purposes, since this element can be easily absorbed by the plants (Gondek, 2008).…”