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

Abstract

<p align="justify"> <span style="font-size:12px;">A category of chromium (Cr)-containing fertilizers is represented by the fertilizers deriving from byproducts of tanning process. Their use is widespread because of their good agronomic response due to the high content of slow release or- ganic nitrogen (N) and carbon (C). They do not represent an environmental hazard because only the non-toxic form of Cr(III) is present. Productive processes may involve chemical, enzymatic or thermal hydrolysis. The final product is characterized by different contents of peptides and free amino acids depending on the type of hydrolysis. Legislation concerning Cr-containing fertilizers is controversial because often do not consider any scientific evidences; nevertheless, the European Union, the United States and countries as Italy, do not set the restriction to Cr(III) and generally only the presence of the toxic form, Cr(VI), is limited. Depending on its two main oxidation forms, Cr issue has been studied for many years. Several authors confirmed that Cr(VI) is carcinogenic, while Cr(III) is an essential trace element in human and animal diet. In soil Cr(III) has low mobility, whereas Cr(VI) is highly water soluble. However Cr(VI) in soil is quickly reduced to Cr(III); on the contrary oxidation of Cr(III) to Cr(VI) is rarely possible because particular conditions must occur. Only a very small fraction of Cr in soil is available to plant uptake and its translocation in edible parts is limited because it is immobilized in roots as Cr(III). Therefore risks of environmental pollution using these fertilizers are negligible; on the contrary they have positive environmental and agronomical effects. The aim of this review is to deal with the category of the organic fertilizers containing Cr derived from tannery processes focusing on its chemical, productive, legislative, environmental and agronomical aspects. Special attention is given to the ambiguous issue of Cr briefly summarizing the most important studies of the last forty years.</span> </p> <p> <span style="font-size:12px;"> </span> </p

Heavy Metals in Soils Associated with Fertilizers in Trinidad

“…This farm used several types of organic fertilizers. No testing was done on these fertilizers but according to Ciavatta et al (Ciavatta et al, 2012), Cr can be present in organic fertilizers derived from tannery industries. Other commonly used fertilizers with levels of Cr included N-P-K (R), potash, and N-P-K (YM).…”

Heavy Metals in Soils Associated with Fertilizers in Trinidad

“…This farm used several types of organic fertilizers. No testing was done on these fertilizers but according to Ciavatta et al (2012), Cr can be present in organic fertilizers derived from tannery industries. Other commonly used fertilizers with levels of Cr included N-P-K (R), potash, and N-P-K (YM).…”

Inactivation of indicator microorganisms and biological hazards by standard and/or alternative processing methods in Category 2 and 3 animal by‐products and derived products to be used as organic fertilisers and/or soil improvers

“…The processing of hides and skins generates by‐products such as hide offcuts and shavings, or soft material from fleshing, which find applications in several industry sectors such as pet and animal food production, fine chemicals including photography and cosmetics, and fertilisers (European Commisssion, online; JRC, 2013 ). For use as organic fertilisers, different end products can be obtained, depending on the transformation process: enzymatic hydrolysis (liquid fertiliser) and thermal hydrolysis (solid fertiliser) (Ciavatta et al., 2012 ).…”