Poultry Litter Land Application: Does This Practice Represent a Threat to Hydric Resources? A Preliminary Study on Poultry Litter Leachate

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, a residue known as poultry litter (PL), composed of bedding material (rice and peanut husks, wood shavings) and bird dejections, is generated. After the animal’s growing period has finished, this material is piled outside the breeding sheds until it is removed by agricultural producers, who use it as fertilizer since it is rich in nutrients and organic matter. These residues contain inorganic pollutants, and their land application can lead to the accumulation of these elements in the soil. In addition, due to the action of rain, leachate could be generated that would allow the entry of these pollutants into different water resources. This work aimed to: i) generate PL leachates at a laboratory scale, testing different pH and time extraction; ii) evaluate the levels of 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 in these leachates; and iii) compare the content of elements in the residues before (PL) and after (EPL) aqueous extraction. Leachates (L) were generated from anaqueous extraction using 1 g of PL, 10 mL of H2O, and stirring at room temperature. Two pH (4.5 and 6.5) and 4 extraction times (1, 2, 4, and 24 h) were evaluated. PL and EPL samples were digested with a mixture of H2O2, HCl, and HNO3. All the determinations were made through Inductively Coupled Plasma Mass Spectrometry. Be, Bi, and Tl were not detected in any of the evaluated matrices. Although the content of all the elements analyzed in the L samples was significantly higher than the content present in the control water, no significant differences were observed at the different pH values evaluated (p > 0.05). However, differences were observed due to the extraction time. The metal content in the L samples increased as the extraction time increased for most elements analyzed. The contents of B, Na, Mg, K, Ni, Rb, and Mo presented significant differences between PL and EPL samples, being higher in PL samples (p > 0.05). These results show that water is an agent capable of extracting these contaminants from the PL matrix. Thus, the pile-up or application of PL as fertilizer represents a potential source for the entry of inorganic pollutants not only into terrestrial ecosystems but also into underground or surface water resources. Therefore, further studies about the behavior of these pollutants in these complex matrices are needed to propose safer disposal methods for these residues.