Soil Application of Tannery Land Plaster: Effects on Nitrogen Mineralization and Soil Biochemical Properties

Abstract

Tannery land plaster (TLP) is a byproduct of lime hydrolysis of leather shavings. Its use in agriculture (organic C ≈ 17%, N ≈ 6% dm) could represent an alternative to landfill or incineration, but the high Cr(III) content (≈5% dm) makes it necessary to evaluate the effect on soil biochemical properties. TLP was therefore added at the rates of 220 and 440 kg of N ha −1 to 2 agricultural soils and incubated for 56 days under controlled conditions. Extractable NH 4 + -N and NO 3 − -N, CO 2 -C evolution, microbial biomass-N, protease activity, and extractable Cr were monitored. The organic N was readily mineralized (>50% in the first week) and a significant increase in microbial activity was measured, regardless of soil type and addition rate. Extractable Cr(III) quickly decreased during the incubation. The absence of a negative impact on soil biochemical properties seems to support the use of TLP in agriculture, although further investigations in long-term field experiments are suggested.

Soil microbial properties after 5 years of consecutive amendment with composted tannery sludge

“…Additionally, SIR may indicate active microbial biomass (Svensson and Friberg 2007) and both microbial biomass and toxicity in soils (Martí et al 2007). The increases in SMB and SIR with the addition of 5 Mg ha −1 CTS after 5 years most likely occurred due to the permanent addition of C sources that favoured the soil microorganisms, as reported previously (Ros et al 2006;Santos et al 2011;Giacometti et al 2012). In addition, our results show that soil microorganisms remained active after CTS amendment.…”

“…Previous short-term studies were completed under controlled laboratory conditions and evaluated the effects of different composted industrial wastes on soil microbial properties (Araújo and Monteiro 2006;Araújo et al 2007;Santos et al 2011;Giacometti et al 2012). Usually, the results showed positive effects of composted waste on soil microbial properties, suggesting no toxic or detrimental effects of the waste application on soil.…”

“…Usually, the results showed positive effects of composted waste on soil microbial properties, suggesting no toxic or detrimental effects of the waste application on soil. However, the effects of repeated applications of composted wastes, mainly under field conditions, should be evaluated to define the long-term effects of the waste on soil microbial properties (Giacometti et al 2012;Silva et al 2014). Additionally, studies employing the repeated application of composted wastes such as composted tannery sludge (CTS) under field conditions are scarce, and the limited information from earlier studies does not provide a clear picture.…”

Chromium-Containing Organic Fertilizers from Tanned Hides and Skins: A Review on Chemical, Environmental, Agronomical and Legislative Aspects

“…Increasing amounts of solid fertilizers applied to soil lead to a negligible rise in soil soluble Cr [2,[45][46][47]. Moreover it was demonstrated that the amount of Cr leached from soil is insignificant [45,48]. Chromium is generally insoluble in soil even when it is released during the mineralization of the organic matter [2,47,48].…”

“…Moreover it was demonstrated that the amount of Cr leached from soil is insignificant [45,48]. Chromium is generally insoluble in soil even when it is released during the mineralization of the organic matter [2,47,48]. The organic constituents of the solid fertilizers play an important role in reducing the amount of Cr available to plants [49].…”