1. ACIAR Project FST/2004/058 - Realising genetic gains in Indonesia and Australia plantations through water and nutrient management Eko B. Hardiyanto

2. Background Acacia plantations (now more than 700,000 ha) are already a major contributor to the Indonesian economy and will increasingly supply wood demand for pulpmill and furniture industriesAcacia plantations (now more than 700,000 ha) are already a major contributor to the Indonesian economy and will increasingly supply wood demand for pulpmill and furniture industries Outgrower scheme of acacia plantation has also been developedOutgrower scheme of acacia plantation has also been developed In Australia an acacia plantation has been set up with a potential size of 75,000 ha in Tiwi IslandIn Australia an acacia plantation has been set up with a potential size of 75,000 ha in Tiwi Island Substantial genetic improvements in growth and form of Acacia mangium have been achieved through tree breeding.Substantial genetic improvements in growth and form of Acacia mangium have been achieved through tree breeding.

3. Background (continued) Among the key factors affecting the realisation of genetic gain are water and nutrient managementAmong the key factors affecting the realisation of genetic gain are water and nutrient management The project aims to improve the profitability and sustainability of acacia plantation in Indonesia and Australia, expanding the involvement of and benefits to small-holder farmers.The project aims to improve the profitability and sustainability of acacia plantation in Indonesia and Australia, expanding the involvement of and benefits to small-holder farmers.

4. Objectives To quantify the role of site edaphic properties and phosphorus in realising gains from deployment of genetic gain across sites, and to develop appropriate management strategies for maximising productivity and economic valueTo quantify the role of site edaphic properties and phosphorus in realising gains from deployment of genetic gain across sites, and to develop appropriate management strategies for maximising productivity and economic value To develop a capacity to predict potential productivity of Acacia mangium in relation to site factors in Indonesia and AustraliaTo develop a capacity to predict potential productivity of Acacia mangium in relation to site factors in Indonesia and Australia To evaluate economic benefits of improved management in outgrower schemesTo evaluate economic benefits of improved management in outgrower schemes To develop practical tools to support improved management.To develop practical tools to support improved management.

5. Project findings The project was started in September 2006The project was started in September 2006 11 sites ranging from low to high productivity have been identified and are used for establishing experimental plots11 sites ranging from low to high productivity have been identified and are used for establishing experimental plots Acacia productivity has significant correlation with soil phosphorus (phosphate retention index and total phosphorus); these will be used for development of phosphorus indices of availabilityAcacia productivity has significant correlation with soil phosphorus (phosphate retention index and total phosphorus); these will be used for development of phosphorus indices of availability

6. Priorities for further research Continuation of genetic improvement, putting more attention on wood quality, not only focusing on growth and formContinuation of genetic improvement, putting more attention on wood quality, not only focusing on growth and form Site management and productivity studies to identify impact of management on the long-term productivity of plantationSite management and productivity studies to identify impact of management on the long-term productivity of plantation Quantification of key physiological and morphological traits of improved genetic material as the basis for modelling potential and real gains under a number of climatic and management scenariosQuantification of key physiological and morphological traits of improved genetic material as the basis for modelling potential and real gains under a number of climatic and management scenarios Quantification of nitrogen fixation and cycling in Acacia mangium plantation, and the impacts of external factors such as soil phosphorus availability on the nitrogen cycling.Quantification of nitrogen fixation and cycling in Acacia mangium plantation, and the impacts of external factors such as soil phosphorus availability on the nitrogen cycling.

7. Priorities for further research (continued) Identification of the possibility of nitrogen fixation is a limiting factor for genetically improved material, which may start to place heavier demands on the nitrogen supply capacity of the systemIdentification of the possibility of nitrogen fixation is a limiting factor for genetically improved material, which may start to place heavier demands on the nitrogen supply capacity of the system Development model for nitrogen demand and supplyDevelopment model for nitrogen demand and supply Identification and quantification of other potential limiting factors for plantation productivity such as availability of potassiumIdentification and quantification of other potential limiting factors for plantation productivity such as availability of potassium Silvicultural and economic studies on sawlog plantation of acacia.Silvicultural and economic studies on sawlog plantation of acacia.