Use of Poultry Litter as Fertilizer: Can an Agroecological Practice Pose a Risk to the Environment?

FACUNDO L. CORTÉS; JULIETA GRIBOFF; NATALIA ALMADA; JUAN MARTÍN GANGE; CARLOS A. HARGUINTEGUY; MAGDALENA V. MONFERRAN

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

SETAC Latin America

During chicken meat production, rice and peanut husks or wood shavings are spread on the breeding shed floor to absorb the excrement of the birds and maintain an appropriate and dry environment for them. Once the growing period has finished, this material, which consists of a mixture of feces and bedding material known as poultry litter (PL), is removed from the sheds and used as fertilizer since it is rich in nutrients and organic matter. Although this practice is widespread in Argentina, where more than 5 million tons of PL are generated each year, it is carried out without knowing the physical-chemical composition of this residue. This study aimed to: i) perform an elemental analysis on PL samples from 3 farms located in Entre Ríos, Argentina; and ii) perform an elemental analysis on clean bedding material (BM) and chicken feed (CF) samples. The content of 30 elements was assessed: Li, Be, B, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sb, Ba, Hg, Tl, Pb, Bi, and U. The samples were digested in a mixture of H2O2, HCl, and HNO3 and analyzed through Inductively Coupled Plasma Mass Spectrometry. The metal content in PL samples presented the following trend: Ca > K > Mg > Na > Al > Fe > Mn > Zn > Sr > B > Cu > Ba > Rb > V > Ni > Mo > Pb > Cr > As > Li > Se > Co > Ag > Hg > U > Sb > Cd. The metal content in BM and CF samples followed the same trend for most elements analyzed. Be, Bi, and Tl were not detected in any of the evaluated matrices. The metal content determined in BM samples was significantly lower than the metal content found in PL samples for all the analyzed elements, except for Cr, which showed no significant differences (LSD Fisher, p > 0.05). On the other hand, the metal content in CF samples presented intermediate values to those found for BM and PL samples. Given these results, we can affirm that the use of PL as fertilizer or soil amendment represents a potential source for the entry of inorganic contaminants to terrestrial ecosystems, from where they can be transferred to the food produced there or reach surface or underground water bodies. In addition, the results obtained for the CF samples would indicate that they are one of the possible sources by which the metals reach the PL through the chicken manure