Influence of pine and miscanthus biochar on the water activity and moisture sorption isotherms of used broiler litter

Abstract

The effect of various inclusion rates of pine biochar (PBC), miscanthus biochar (MCB) and starting moisture contents on the water activity (Aw) of broiler litter/biochar mixtures was examined. Suitable models for the resulting moisture sorption isotherms were also evaluated. For poultry mixed with PBC and MBC, higher starting moisture contents led to increased Aw. Aw generally increased at high inclusion rates of PBC and MBC, which may be explained by the porous nature and general hydrophobicity of BC. Of the five models examined, the exponential rise to maximum was considered to be the most useful due to its accuracy at moisture contents similar to those commonly found in commercial poultry houses (10–30 % wet basis). Accuracy of models was determined using R2, mean squared prediction error (MSPE), and mean absolute percent error (MAPE). In general, higher inclusion rates of biochar resulted in less overall prediction accuracy. Results from this paper indicate that several moisture isotherm models can be used to effectively model the relationship between moisture content and Aw in broiler litter and biochar mixtures.