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Centre for Plant & Water Science 2008 Annual Report STUDIES ON WOODLANDS INVADED BY Allocasuarina littoralis SUMMARY Woodland thickening is a worldwide phenomenon which is caused in part by changed land management regimes. To assess the effectiveness of fire and chemicals as agents capable of restoring woodland structure, field experiments were designed aimed at thinning a dense midstory of Allocasuarina littoralis in a long unburnt woodland site. Experimental design and initial observations Un-invaded woodlands were characterised by a tree basal area of around 15 to 17 m 2 /ha. The Allocasuarina invaded sites possessed around 3000 stems of Allocasuarina per hectare, contributing an additional 10 m 2 /ha. However, the ground layers of these sites were composed of a similar species richness of native grasses and legumes as un-invaded woodland nearby, but with a much reduced biomass. It was therefore hypothesised that the ecosystem would have a seed bank of remnant species that would support restoration if the Allocasuarina could be successfully removed from the system. Four replicates of three treatments (fire, chemical and fire + chemical) and controls were placed in a random block design on the experimental site which has a total area of 8.6 hectares. Fire experiments are notoriously difficult to conduct successfully and safely in the field and this experiment proved to be no different. Fig 1. The block on the left had a deep litter layer but low grass height and biomass resulting in no foliage scorch, compared to the block on the right with scorch heights to 6 meters. The latter block is adjacent to an open area which facilitated the growth of a large body of unpalatable native grass to 1 meter. PROJECT STAFF Principal Investigators: Co-Principal Investigator: Others: FUNDING CQUniversity INCOME $0 Dixie Nott, Prof Kerry Walsh Dr Alistair Melzer (CEM) Dr Bill Burrows 29
Centre for Plant & Water Science 2008 Annual Report COMPOST TEA AS A MICROBIAL ENHANCER IN CROP PRODUCTION SUMMARY Compost tea is a microbially enhanced extract after incubating compost in water with microbial food sources (Ingham, 2005) for which many claims have been made. This research sets and tests hypotheses in the context of these claims. The following hypotheses have been established as to the efficacy of compost tea in terms of: (a) ability to directly improve plant nutrition via the nutrient content of the compost tea; (b) ability to improve plant nutrition through an indirect action, via microbial action in mineralising or solubilising of organic and inorganic components of the soil; (c) ability to offer bio-protection against a fungal pathogen (e.g. Fusarium oxysporum f. sp. lycopersici); (d) ability to accelerate litter decomposition; and (e) ability to provide protection to root growth against high levels of aluminium (Al) ions, via chelation of Al ions by humic acids or uptake by microbes. Using the experimental pots containing a previously grown tomato root systems in two soil types, the effect of addition of non-sterilised and sterilised aerated compost tea (ACT) on growth of a sorghum crop was assessed (addressing hypotheses ‘a’ and ‘b’). There was no significant difference either between the two treatments or amongst the prior fertiliser treatments in the average weight of aboveground sorghum biomass, harvested 50 days after sowing (DAS) although a significant difference was observed between the two soil types. Statistical analysis also revealed an interaction between four prior (tomato crop) treatments (control, ACT, non-aerated compost tea or NCT and chemical) and soil types (P
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Centre for Plant & Water Science - Central Queensland University

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