Dr Brian Kelleher

Soil microbes are central to many soil processes, but due to the structural complexity of soil organic matter, the accurate quantification of microbial biomass contributions continues to pose a significant analytical challenge. In this study, microbes from a range of soils were cultured such that their molecular profile could be compared to that of soil organic matter and native vegetation. With the use of modern NMR spectroscopy, the contributions from microbial species can be discerned in soil organic matter and quantified. On the basis of these studies, the contributions of microbial biomass to soil organic matter appear to be much higher than the 1–5% reported by other researchers. In some soils, microbial biomass was found to contribute >50% of the extractable soil organic matter fractions and ∼45% of the humin fraction and accounted for >80% of the soil nitrogen. These findings are significant because organic matter is intimately linked to nutrient release and transport in soils, nitrogen turnover rates, contaminant fate, soil quality, and fertility. Therefore, if in some cases soil organic matter and soil organic nitrogen are predominately of microbial origin, it is likely that this fraction, whether in the form of preserved material or living cells, plays an underestimated role in several soil processes.

Biomass gasification is a possible alternative to the direct use of fossil fuel energy. Biomass, a CO₂ neutral source of renewable fuel, can contribute to the demand for heat, electricity and synthesis gas. However, there are inefficiencies in the technology, which at present render biomass gasification economically unviable. The presence of condensable organic compounds and methane in the product gas renders the gas unsuitable for specific applications. Elimination of the condensable organic compounds and methane by a suitably cheap technology will enhance the economic viability of biomass gasification. This paper contains an extensive literature review of the three main groups of catalysts, which have been evaluated for the elimination of these hydrocarbons. These three groups of catalysts are dolomite, alkali metals and nickel.

The land disposal of waste from the poultry industry and subsequent environmental implications has stimulated interest into cleaner and more useful disposal options. The review presented here details advances in the three main alternative disposal routes for poultry litter, specifically in the last decade. Results of experimental investigations into the optimisation of composting, anaerobic digestion and direct combustion are summarised. These technologies open up increased opportunities to market the energy and nutrients in poultry litter to agricultural and non-agricultural uses. Common problems experienced by the current technologies are the existence and fate of nitrogen as ammonia, pH and temperature levels, moisture content and the economics of alternative disposal methods. Further advancement of these technologies is currently receiving increased interest, both academically and commercially. However, significant financial incentives are required to attract the agricultural industry.