(LEFT) Researchers in Western Australia are investigating the interaction of water and fertiliser inputs in oil mallee production to deliver a sustainable level of biomass supply in the long run for commercial purposes. (Photo: Richard Bennett, CSIRO)
Timely research
Intensive sites set to monitor mallees
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orking out how to maximise mallee biomass production through better water and nutrient utilisation is the focus of two new Future Farm Industries CRC experimental sites near Narrogin and Wickepin, Western Australia. As part of the larger Water and Nutrients for Woody Crop project, with 17 sites investigating oil mallees, project leader Dr Daniel Mendham (CSIRO) and his team are focussing their attention on the interaction of water, nutrients and management options to maximise returns to farmers. This project is part of the Future Farm Industries CRC’s New Woody Crop Industries program, which aims to develop woody perennial systems for southern Australia. The program is also investigating how to provide new farm income sources, sinks for carbon and surplus water, and better environmental protection for farmland. “Through our intensive research sites at Narrogin and Wickepin we aim to answer several key questions,” Dr Mendham said. “We want to know if we can intercept short-slope run-off to fill the ‘dry soil dam’
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that develops under mallee belts and to determine how effectively mallees use available water and nutrients throughout the year to produce biomass.”
Drying effect Prior studies have revealed a large ‘dry dam’ underneath belts of planted mallees. “The trees are extracting soil water to a depth of at least 10 metres,” Dr Mendham said.
• The Water and Nutrients for
Woody Crops project is funded through the Second Generation Biofuels Development Program.
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“We have several soil moisture probes at different depths and can measure infiltration. As the trees use the water we can measure as it transpires through the tree using sap flow meters,” Dr Mendham explained.
Practical applications
Earlier during the year one of the sites received about 90 millimetres of rain over a couple of hours and Dr Mendham is keen to capitalise on this type of rainfall event. “We want to try and trap run-off using some engineered contour banks and direct it into the soil so the trees can use it at will,” Dr Mendham said.
Nutrition comes next
• Researchers are intercepting •
One project goal is to track the value of water applied at different times of the year. Researchers will irrigate the trees across a selection of treatments and measure tree response.
“The trick is to see if we can capture surface run-off to water the trees.”
“Because we plan to harvest whole tops from the mallees there is potential for significant quantities of nutrients to be exported with the biomass,” Dr Mendham explained.
Results will be used to develop input models to boost biomass ready for an increasing demand by the biofuel industry
Existing information in other tree crops suggests that 5–6 cubic metres of wood is produced per megalitre. But as humidity drops and temperatures increase trees produce less wood per megalitre.
“There is some lateral movement but not much, although the soil is drying at least 20 m either side of the belt.”
• Two intensive experimental sites
rainfall run-off using engineered contour banks for demand-driven use by mallees
“In order to know what value that water has we need to measure how much biomass (tonnes of material) is produced per millimetre of available water,” Dr Mendham said.
“The aim is to better understand any interaction between water availability, nutrient uptake and biomass production to enable better strategic management of mallee belts to allow sustainable levels of biomass production.”
Water is not the only input under investigation. Dr Mendham and his team are also monitoring the role of nutrients in biomass production.
are investigating the interaction of water and nutrients on oil mallee biomass production
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By Catriona Nicholls
Researchers also are keen to find out whether there are strategic times throughout the year where water is more valuable for biomass production.
“Part of this project will be to quantify nutrient export under a range of conditions, including different rotation lengths and types.” The final piece of the jigsaw is to determine whether there is an interaction between water and nutrient availability. “It follows there is probably a level of interdependency between the two,” Dr Mendham said.
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Former Future Farm Industries CRC PhD student Richard Bennett is charged with running the two sites. “Being native, mallees are adapted to the environment, but when planted intensively in belts there is increased competition for water and nutrients. After a couple of years growth the competition limits the water and nutrients,” Richard explained. “The idea is that if we can give them more of what they need they can grow faster and be more sustainable in the long run for commercial purposes.” “By measuring sap flow we can tell how much water each tree is using. By having instruments on the trunk we can also determine how much they expand and contract throughout the year and over longer periods as they grow,” Richard said. This information will allow the team to calculate water use efficiency, which can be extended to calculations of additional water application and potentially greater biomass. “By studying the interactions intensively at one site we want to gain a physical understanding of how the process works. This information can be put in a model to allow broader application further down the track,” Richard said.
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RIGHT: Dry dam belts are developing under belts of mallees (TOP RIGHT) and researchers are hoping to trap rainfall run-off using engineered contour banks (BOTTOM RIGHT) to water the trees. (Photos: Richard Bennett, CSIRO)
“We also will be able to extend these outcomes to other sites.”
The bigger picture To be sustainable, mallee-based processing industries need confidence that feedstock will be sustainably produced well into the future. As with all crop production, key factors affecting potential productivity are; water, nutrients and crop physiology. “As mallee managers, we have the ability to influence each and every one of these factors,” Dr Mendham said. “While only in the start-up phase, the project will develop our knowledge, understanding and tools to underpin sustained productivity of mallees.” Acknowledgements: The Australian Department of Resources, Energy and Tourism’s Second Generation Biofuels Research and Development Program is a key project supporter.
More information Dr Daniel Mendham, CSIRO T: (08) 9333 6663 E: daniel.mendham@csiro.au
Mallee biomass ready for biofuel boom
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esearchers at Curtin University’s Centre for Advanced Energy Science and Engineering’s are turning up the heat on investigations into the utilisation of mallee biomass in Western Australia. Their efforts are currently focussed on the following mallee utilisation technologies: • Production of liquid fuels and chemicals by pyrolysis and biorefinery. The Centre leads a large collaborative project involving some key WA mallee researchers, funded by the Australian Federal Government as a part of its Second Generation Biofuels Research and Development Grant Program along with State Government and participating organisations. The Centre also collaborates with its United States partner at the Washington State University, which is funded under the Australian Government’s International Science Linkage program • Bio-char. As an essential part of the above project researchers also are investigating the production and use of bio-char as a soil
conditioner and for carbon sequestration, including life cycle analysis. This is in close collaboration with the researchers in the WA Department of Environment and Conservation (DEC), CSIRO, the Future Farm Industries CRC and Centre for Research into Energy for Sustainable Transport • Novel mallee gasification technology. Following intensive fundamental research on the gasification behaviour of mallee biomass, researchers have built a laboratory-scale pilot plant to demonstrate the key features of their innovative technology. If successful, the technology can be used to generate electricity for use by regional and rural WA with locally-grown mallee. It is predicted the technology could meet the energy demand of the booming regional economy. This project is funded by the Australian Government as a part of the Asia-Pacific Partnership on Clean Development and Climate in collaboration with researchers in China, Korea and Japan
• Hydrolysis of mallee biomass. Researchers aim to hydrolyse mallee biomass to produce sugars that may be further utilised, such as through fermentation to produce bio-ethanol • Other technologies. Centre researchers are investigating other possible ways to use the mallee biomass, such as co-firing mallee (or mallee-derived fuels) in the existing coal-fired power plants or fuel cell technologies. Co-firing mallee in existing power plants may encourage uptake of mallee biomass as a renewable energy source. On the other hand, fuel cell technologies will give high efficiency for mallee utilisation.
More information Professor Chun-Zhu Li, Curtin Centre for Advanced Energy Science and Engineering T: (08) 9266 1131 E: chun-zhu.li@curtin.edu.au
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