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Vermicomposting is an established process to convert organic wastes into vermicastings suitable for plant growth. This research investigated the vermicomposting of anaerobic digestate with four different ratios of sawdust as a bulking material, for 75 days. The optimum proportion of anaerobic digestate to sawdust was identified as 70:30 based on worm growth and reproduction. Vermicomposting process increased the conversion of ammonium into nitrate when compared with control (p = 0.05). Vermicastings produced at the end of this experiment had significantly high N, NO3-N, P and K than the control (p = 0.05). There was significant reduction in pathogen levels by the worms (99%), and also a germination test undertaken showed an 83% increase in radish seed germination after vermicomposting when compared to raw digestate. The results indicated that vermicomposting with Eisenia fetida is a sustainable technology to convert the anaerobic digestate into nutrient-rich, safe to handle vermicastings, which otherwise is a secondary pollutant.

The Republic of South Africa (RSA) is the first developing country to plant genetically modified staple food - Bt white maize. The following paper describes the development and spread of Bt maize in RSA that started in 1998. After that, based on surveys of 33 large commercial Bt maize farmers and 368 smallholders in 2001/2, it shows that Bt maize gives higher yields for both groups and reduces pesticide use particularly for the large commercial farmers. The paper concludes with a discussion of policy options which would make the Bt maize more accessible to more small holders.

The whole of landscape regenerative processes are being studied to determine their effect upon carbon bio-sequestration in agricultural soils. The Mulwaree Ponds drainage system, south of Sydney, shows the effects of overgrazing by fine wool sheep over the past 160 years and the resultant loss of perennial groundcover causing nutrient leaching into Sydney's drinking water catchment. Natural Sequence Farming methods, in combination with the strategic application of composted, recycled, organic waste, will be trialled to measure: a) the increase in stable soil carbon content; b) the improvement in water infiltration and retention in agricultural soils; c) the increase in biodiversity and suppression of undesirable vegetation; d) the sustainability and profitability of low input farming practices. Land owned and managed by conventional farmers will be subjected to this innovative agricultural regime in the belief that former 'doubters' make the best 'believers'. This paper details the methodology involved in the demonstration site which will assist in arguments linking increased soil carbon levels to mitigation of the effects of climate change.

Bidens pilosa L. (commonly known as cobbler's peg) is an annual broad leaf weed widely distributed in tropical and subtropical regions of the world and is reported to be a weed of 31 crops, including wheat. Automatic detection of Bidens in wheat farms is a non-trivial problem due to their similarity in colour and presence of occlusions. This paper proposes a methodology which could be used to discriminate Bidens from wheat to be used in operations such as autonomous weed destruction. A spectrometer is used to analyse the optical properties of Bidens and wheat leaves while achieving high classification results. However, due to the practical constraints of using spectrometers, a colour camera-based technique is proposed. It is shown that the colour-based segmentation followed by shape-based validation algorithm gives rise to high detection rates with lower false detections. We have experimentally evaluated the algorithm with Bidens detection rate of 80% and a false alarm rate of 10%.