Lignite reduces odour from broiler farms without reducing production performance.

An unavoidable consequence of chicken meat production is the generation of substantial quantities of spent litter. This poses several environmental and social challenges, as broiler farms become hotspots for odour emissions. The main source of odour from broiler litter is the microbial decomposition of organic material. Thus, lignite's previously shown capacity to reduce microbial activity in broiler litter was expected to reduce odour emissions from broiler housing. The effect of lignite on odour emission rate (OER) (ou/s) was investigated using dynamic olfactometry over two consecutive summer broiler grow-out cycles in Victoria, Australia, with lignite applied at 3.5 kg/m2. The air quality dispersion model, AERMOD, was used to investigate how lignite's effect on OER influenced the predicted odour dispersion distances and concentrations in the context of various Australian regulatory requirements. Additionally, the effect of lignite on bird production performance was also determined. This study showed that lignite reduced the OER from commercial broiler housing by an average of 56% over both grow-outs. This effect was observed for the duration of the trial. The observed reduction in OER reduced the required separation distances by 44-53% according to the state odour criteria for Victoria, New South Wales, Queensland and South Australia. There were no observed differences in feed conversion ratio, bird live weight or mortality throughout either grow-out. This study demonstrated the capacity of lignite to reduce odour emissions from commercial broiler housing without reducing bird production performance.

Lignite reduces carbon and nitrogen loss from litter in commercial broiler housing.

The loss of carbon and nitrogen from broiler litter limits nutrient recycling and is damaging to the environment. This study investigated lignite, a low-rank brown coal, as an amendment to reduce the loss of carbon and nitrogen from broiler litter over 3 consecutive grow-out cycles, November 2021 to May 2022, at a commercially operated farm in Victoria, Australia. Lignite-treated litter contained significantly more carbon and nitrogen, with an increase of 70.1 g/bird and 12.6 g/bird for carbon and nitrogen, respectively. Lignite also reduced aerobic microbial respiration, with a 46.0% reduction in CO2 flux recorded in week 7 of the study, resulting in reduced mass loss. It is expected that this is a key mechanism responsible for nutrient retention in litter following treatment with lignite. Furthermore, lignite treatment lowered litter moisture content by 7, 6 and 3 percentage points for grow-out 1, 2 and 3, respectively. These findings present lignite as a beneficial litter amendment for increasing the nutrient value of waste and reducing carbon dioxide emissions. The study highlights the potential of lignite to reduce the environmental impact of poultry production and presents an alternative use for lignite as an existing resource.

Lignite, dewatered lignite and modified subbituminous coal reduce nitrogen loss from broiler litter.

Broiler litter is generated in large quantities as a waste by-product of chicken meat production. N may be lost from the litter and emitted from bird housing as gaseous NH3, which can be damaging to the environment and limit the recycling of a valuable nutrient. This study investigated the effect of lignite application rate (0, 5, 10, 15, 20%) on N loss from broiler litter in a static chamber laboratory incubation. Lignite was subsequently dewatered and subbituminous coal modified by aerobic thermal oxidation and their ammoniacal N adsorption potentials were characterised. In a second static chamber incubation, the capacity of these materials (applied at 20%) to reduce N loss from litter was investigated. Finally, their potential to directly reduce NH3 emissions was examined using a chamber acid trap system. This study showed that lignite reduced N loss when applied to litter at a rate ≥ 5%, with the amount of N retained increasing with increasing lignite application rate. Litter treated with 20% lignite retained 24% more N than untreated litter. Following aerobic thermal treatment, maximum ammoniacal N adsorption capacities of the materials were as follows: lignite > dewatered lignite > modified subbituminous coal > subbituminous coal. Despite inequalities in adsorption capacity, lignite, dewatered lignite and modified subbituminous coal reduced total N loss by 17.3, 18.2 and 18.4% and NH3 emissions by 41.6, 49.1 and 29.8%, respectively. This study demonstrates the potential of coal-based materials to reduce NH3 emissions from broiler litter and increase the nutrient value of waste by reducing N loss.