Realising genetic gains in Indonesian and Australian plantations through water and nutrient management

A total of approximately 23 sites with a range of productivities were initially screened (13 in Indonesia and 10 in Australia) for their suitability for experimental establishment. Surface soil analyses were conducted on the 13 Indonesian sites, and they showed a weak relationship between measured productivity and soil phosphorus characteristics, but there were few other correlative factors. Investigations are continuing into the causes of site to site variation.

Eight experiments are being established in Indonesia (2 core sites and 6 satellite sites), and 4 in Australia. Sites were selected to cover a range in contrasting water and nutrient availability to explore the impacts that these factors have on productivity and response. The core sites in Indonesia compare a range of genetic material (best genetics, intermediate, unimproved, and 'common' which is material that is sourced from Oriomo province of Papua New Guinea, similar to that which is deployed in Australian plantings) at 2 levels of phosphorus supply (zero and 100 kg P/ha). In both countries, performance of the best available genetic material is assessed in a range of phosphorus supply treatments (which also include basal nutrients), and in a high P treatment without basal nutrients. The 6 satellite sites in Indonesia each have 4 rates of P application, replicated 3 times. These sites were planted in both countries in February-April, 2007. Treatment installation and maintenance is ongoing, but initial establishment has been successfully completed.

In addition to the field activities, a review of available physiological information on Acacia mangium has been completed, and the numerous apparent gaps are being filled through targeted field campaigns. An end-of-wet-season campaign has been completed on Melville Island (April 16-27, 2007), and plans are in place to follow up with an end-of-dry-season campaign in September 2007. Amongst other things, the physiological responses of A. mangium and A. crassicarpa to light, CO2, temperature and P supply have been quantified. Acacia crassicarpa was included as a comparison species because of field observations that it tends to grow slower during the wet season, but continues growing for longer into the dry season compared to A. mangium. Mr Daryono Prehaten (who will soon take up a John Allwright fellowship within this project) will follow up on some of the more promising research opportunities in relation to physiological responses to environment and genotype.

In both countries, only limited information exists on soils, and outcomes from this project will contribute knowledge on soil chemistry in the focus areas of both countries. A significant amount of 'synthetic' (i.e. interpolated surface) climatic information is available for both countries (e.g. SILO in Australia and University of Norwich Climate Research Unit data in Indonesia), but this information has been found to be inaccurate on Melville Island, and it is probably only useful in both countries for indicative climate and historical patterns. Investigations are continuing into more detailed soils and climatic information for the 2 target areas. A second John Allwright fellow, Mr Gunawan Wibisono, will be starting in July 2007, and he will be exploring the relationships between soil and nutrient supply in A. mangium plantations.

On the socio-economic sub-project, a survey of small farmers has been conducted by Dr Fachrurozzie Sjarkowi and colleagues to explore the limiting factors to adoption of A. mangium plantations. Two scientific papers from these studies have been prepared in Bahasa Indonesia, and are currently being translated into English.

In summary, the project is generally proceeding according to plan, and is on track to deliver the planned outcomes.

This year we made significant progress on several fronts. We established the remaining field sites, developed an understanding of key physiological responses and incorporated these into a draft parameter set for CABALATM, improved our understanding of the socio-economic basis for decision making by small farmers, hosted training visits by four Indonesian scientists to Australia, including commencement of 2 postgraduate candidates. We also developed a simple methodology for site classification to assist with predicting potential productivity based on soil characteristics.

This year we established 6 new field experiments in each of Sumatra and Australia bringing the total number of sites to 12 in each location and 24 in total. Initial productivity measurements at the sites established in 2007 showed significant growth responses to application of P at all satellite sites. At all sites there was a growth response to at least 10 kg P/ha, and some sites responded further to 50 and 150 kg P/ha. The shape of the response curves indicate that higher rates may yield even higher productivities. Application of basal fertilisers (micronutrients and cations) did not increase early growth in Sumatra, but a response was observed at most sites in Australia. The Australian sites also responded to application of phosphorus at rates up to 100 kg P/ha. Early results from the core experiment have shown that responses to phosphorous are genotype specific , with the best genetic material more responsive to higher rate of phosphorus than the unimproved and moderately improved material. These results will be important in building decision support tools, and for validating the upper productivity envelope for model predictions.

We have been exploring simple measures of potential productivity to allow growers to objectively characterise their sites to assist in making decisions about suitability and profitability of acacias. In this regard, Mr Makruf Nurudin completed a UNESCO international research course in August 2007, for which he studied soil physical and chemical characteristics in relation to productivity across the 12 sites which were part of the initial screening of prospective experimental sites. His report, entitled "Application of soil colour to assess productivity of Acacia mangium plantation in Indonesia," demonstrated that low productivity sites were characterised by soil profiles with shallow plinthite layers, indicating tendency for waterlogging, and conversely, that soils with deep haematite were generally better drained and were more productive. These minerals can potentially be identified via soil colour, thus allowing for the development of a simple tool to allow farmers to characterise site productive potential.

Physiological characterisation of A. mangium continued, with an end-of-dry season campaign completed in September 2007 on Melville Island, and 2 shorter measurement campaigns in Sumatra studying photosynthesis rates, stomatal response, and water potential under different phosphorus treatments. Based on the results of these studies and a literature review, we developed a draft CABALA parameter set for A. mangium. This parameter set will be tested against A. mangium growth data over the next 12 months.

Socio-economic studies have continued, with a national paper being published arising from the first survey of small holder farmers and the factors that are important in their decision making about establishment of Acacia mangium or alternative land use. Activities this year have included an analysis of the economics of previous Acacia rotations, and comparison with alternative land uses, the results of which are currently being written up.

Another key progress point during the year was commencement of 2 new John Allwright fellows, both of whom started in July 2007 at the University of Western Australia. Mr Gunawan Wibisono is studying for his PhD, and Mr Daryono Prehaten has enrolled in a Masters degree. Both of these student projects are tightly aligned to the overall ACIAR project, with Wibisono studying nitrogen cycling in A. mangium plantations, and Prehaten is exploring the impact of genotype and nutrition on photosynthesis, water relations and physiological response to drought. Both of these studies are contributing to the overall understanding and capacity to model A. mangium.

In summary, the project is proceeding according to plan, and is additionally achieving a deeper understanding of the system than originally envisaged through the activities of the 2 John Allwright fellows.