Organic Matter Dynamics in the Wet Tropics Under Different Sugarcane Residue Management Regimes

Retention of sugarcane leaves and tops on the soil surface after harvesting has almost completely replaced pre- and post-harvest burning of crop residues in the Australian sugar industry. Since its introduction around 25 years ago, residue retention has increased soil organic matter to improve soil fertility as well as improve harvest flexibility and reduce erosion. However, in the wet tropics residue retention also poses potential problems of prolonged waterlogging, and late-season release of nitrogen which can reduce sugar content of the crop. The objective of this project is to examine the management of sugarcane residues in the wet tropics using a systems approach. Subsidiary objectives are (a) to improve understanding of nitrogen cycling in Australian sugarcane soils in the wet tropics, and (b) to identify ways to manage crop residues to retain their advantages and limit their disadvantages. Project objectives will be addressed using several approaches. Historic farm production data recorded by sugar mills in the wet tropics will be analysed to determine the effect of residue burning or retention on crop yield and sugar content. The impact of climate on soil processes will be highlighed by development of an index of nitrogen mineralisation using the Agricultural Production Systems Simulator (APSIM) model. Increased understanding of nitrogen cycling in Australian sugarcane soils and management of crop residues will be gained through a field experiment recently established in the Australian wet tropics. From this experiment the decomposition and nitrogen dynamics of residues placed on the soil surface and incorporated will be compared. The effect of differences in temperature, soil water content and pH will be further examined on these soils under glasshouse conditions. Preliminary results show a high ammonium to nitrate ratio in tropics soils, which may be due to low rates of nitrification that increase the retention of nitrogen in a form (ammonium) that is less subject to leaching. Further results will be presented at Congress.

The International Consortium on Mental Health Policy and Services: objectives, design and project implementation

The concept of the burden of disease, introduced and estimated for a broad range of diseases in the World Bank report of 1993 illustrated that mental and neurological disorders not only entail a higher burden than cancer, but are responsible, in developed and developing countries, for more than 15% of the total burden of all diseases. As a consequence, over the past decade, mental disorders have ranked increasingly highly on the international agenda for health. However, the fact that mental health and nervous system disorders are now high on the international health agenda is by no means a guarantee that the fate of patients suffering from these disorders in developing countries will improve. In most developing countries the treatment gap for mental and neurological disorders is still unacceptably high. To address this problem, an international network of collaborating institutions in low-income countries has been set up. The establishment and the achievements of this network-the International Consortium on Mental Health Policy and Services-are reported. Sixteen institutions in developing countries collaborate (supported by a small number of scientific resource centres in industrialized nations) in projects on applied mental health systems research. Over a two-year period, the network produced the key elements of a national mental health policy; provided tools and methods for assessing a country's current mental health status (context, needs and demands, programmes, services and care and outcomes); established a global network of expertise, i.e., institutions and experts, for use by countries wishing to reform their mental health policy, services and care; and generated guidelines and examples for upgrading mental health policy with due regard to the existing mental health delivery system and demographic, cultural and economic factors.