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Animal manure is an important source of nutrients for crop production, but environmental issues can restrict its direct use. Thermochemical processing these manures may be an alternative to concentrate nutrients and reduce the final volume for agriculture application. We aimed here to evaluate the viability of extracting nutrients from chicken manure using a thermochemical process which reduces the volume of transported nutrients, targeting phosphorus (P) recovery as precipitated struvite, without add external source of P. The extraction of nutrients from poultry manure was performed in water, followed by a thermochemical treatment of the solid phase by incineration and acidulation of the resulting ash. Struvite was produced from the acidified ash extract after supplementation with Mg and regulating the pH (~8.5) by KOH addition. The recovery efficiency of P from the poultry manure and incorporation into struvite was 90%. The final product was a multi-nutrient fertilizer with high macronutrient levels (P, K, Mg and S) and low micronutrient content when compared to fresh manure, as well as lower levels of heavy metals, potentially harmful for the environment. The precipitated product obtained here is composed of struvite-NH 4 and struvite-K, alongside appreciable quantities of potassium sulphate and hydroxyapatite carbonate. Overall, we conclude that poultry manure represents a viable source of P and N for struvite production resulting in a nutrient-rich, pathogen-free inorganic fertiliser suitable for widespread use in agriculture., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Whereas soil test information on the fertility and chemistry of soils has been important to elaborate safe and sound agricultural practices, micro-scale information can give a whole extra dimension to understand the chemical processes occurring in soils. The objective of this study was to evaluate the effects that the consecutive application of untreated poultry litter, alum-treated litter or ammonium nitrate (NH 4 NO 3 ) had on P solubility in soils over 20 years. For this, we used soil test data, sequential chemical fractionation (SCF) of P, and P K-edge XANES and μ-fluorescence spectroscopies. Water extractable P data indicated that application of alum to poultry litter was a very effective treatment for reducing P solubility. On the basis of our SCF of P data, P was primarily found within the 0.1 M NaOH pool across the applied rates and regardless of the treatment, where application of alum-treated litter accounted for as much as 59 ± 2% of the total, followed by NH 4 NO 3 , 49 ± 4%, and untreated litter, 40 ± 2%. It was also shown that in soils where alum-treated litter was applied, the Resin pool accounted for 10 ± 1% of the total, followed by NH 4 NO 3 , 13 ± 4%, and untreated litter, 18 ± 2%, indicating that P was less readily available in soils where alum-treated litter was applied. Phosphorus XANES indicated that P was predominantly associated to Fe > Al > Ca > organic molecules, regardless of the treatment or applied rates, though the formation of PoAl complexes was only found in soils that received application of alum-treated litter and was positively related to the applied rates. The combination of P-XANES with SCF or μ-fluorescence data was shown to provide valuable information about P reactivity and distribution in soils and should thus be used to address the fate of applied P amendments in soils., (Copyright © 2018 Elsevier Ltd. All rights reserved.)