Characterization of Maturity Level in Laying Hen Manure by Chemical and Thermogravimetric Analysis

Abstract

This study aims at investigating maturity levels in manure from laying hens in order to encourage its agronomic re-utilization. In fact the use of unstable/insufficiently mature manure could potentially damage both soils and crops. Effective, easy to reproduce methods are needed in order to assess bio-stabilisation and maturity levels, particularly for biomass that has not undergone conventional composting. This study compares samples of caged laying hen manure, an organic matter rich in nutrients, N and P and devoid of litter or bulking agents, at different levels of maturation. Both chemical (dry matter, ashes, carbon and its fractioning, total and ammoniacal nitrogen) and physical methods, such as thermogravimetry, were used to characterize them. Such physical methods do introduce any sample modification and shorten the analysis time. From a statistical point of view, chemical methods are effective only in distinguishing among different drying methods connected with manure management systems. Only thermogravimetric analysis can identify mature samples by means of total mass loss in the range RT-900°C, mass loss in the range 350-425°C and energy release at 500°C. In addition, thermogravimetric profiles could be used to define a fingerprint for this kind of biomass.