Date & Time: 
Tuesday 10 July 2018

University of Queensland scientists are launching a new monthly series of seminars focussing on nutrient stewardship and the development of next generation fertilisers.

Coordinated by UQ’s Professor Susanne Schmidt, this interdisciplinary group will include input from industry and government stakeholders.

This seminar series explores Nutrient Stewardship with interdisciplinary research and development across agriculture and biology, process and material engineering, social and economic contexts.

The overall aim is to avoid waste and pollution and achieve a circular nutrient economy:

  1. Nutrient efficient plants and crop systems
  2. Technology and material innovation to prevent nutrient losses
  3. Nutrient recycling technology to efficiently repurpose nutrients from (in)organic wastes
  4. Reducing the greenhouse footprint of fertilisers
  5. Functional fertilisers: crop probiotics, bio-stimulants, bio-hydrogels
  6. Technologies to synchronise nutrient release from fertilisers and crop nutrient demand
  7. Next-generation fertilisers that improve soil function and carbon sequestration
  8. Nutrient stewardship in social and techno-economic contexts and future bio-economies

Planning the Nutrient Stewardship Initiative 2018

Seminar schedule in 2018

Due to a teaching committment in first semeseter 2018, Professor Susanne Schmidt is only available on the second Tuesday of each month.

For more information, please contact Professor Susanne Schmidt.

Next scheduled meeting: Tuesday, 10 July 2018 (midday – 1.00 pm)

Room 275
Global Change Institute (Blg 20)
The University of Queensland, St Lucia

10 July

The microdialysis perspective of N availability, and the implications for future soil N research

Scott Buckley, PhD Candidate
BMus BSc (Hons)
Ecophysiology and Plant Nutrition Group
UQ Faculty of Science, School of Agriculture and Food Sciences

Phone: (07) 3365 2732

Nitrogen (N) availability is an important factor in ecosystem function and reflects the proportion of total N which is immediately accessible by plants and soil microbes. However, the soil N cycle is a complex system in constant change – affected by many physical, chemical and biological factors of the soil environment – making estimations of plant-available N difficult. In addition to this, soil researchers often use destructive extraction techniques to sample soil N, which lead to artefacts that bias our findings. There is a desire to find new sampling methods which minimise soil disturbances and provide a plant-relevant perspective of soil N availability.

Our work explores the development of microdialysis – a novel sampling method initially developed for low-disturbance biomedical research. Using small probes (0.5 mm x 10 mm) that act like an artificial plant root, the technique samples compounds through passive diffusion, and can be deployed in situ into intact soil with minimal disturbance. We have found the technique often offers a different view of N availability in soil to that of conventional extractions; most notably, a greater dominance of organic N, in contrast to inorganic N (particularly NH4+) in extracted samples. The method also provides a measurements of N flux relevant to many soil processes, such as plant uptake.

My PhD research seeks to explore further the microdialysis perspective of N availability, and the implications for future soil N research. This talk will act as an introduction to the technique, highlighting our work investigating the apparent differences between sampling methods in more detail, and how these measures may relate to plant-available N. We explore extensions of the technique to sample larger molecular-weight N such as protein and discuss ways to optimise the technique for better sensitivity in complex soil environments.

Scott Buckley
Scott is a final-year PhD student, investigating nitrogen availability in soil, and the implications of the assumptions we make when measuring it. Scott received a Bachelor of Science (Honours) in 2014, and a Bachelor of Music (2005), and has a parallel career as a music composer and arranger.   

Previous speakers

12 June 2018nutrient stewardship - Johannes Biala

Reducing Greenhouse Gas Emissions and Improving Nutrient Use Efficiency in the Manure Supply Chain

Johannes Biala - Centre for Recycling of Organic Waste and Nutrients UQ School of Agricultural and Food Sciences, Gatton


A three-year federally funded project followed the greenhouse gas (GHG) balance and nutrient supply capability of stockpiled and composted manure from the intensive dairy, feedlot (beef), pork and layer chicken industries both during stockpiling / composting, and following repeat application in an intensive horticultural production system. Nitrous oxide was the largest contributor to the overall GHG processing budget, accounting for up to 90% of total emissions. Composting of manures did not consistently reduce GHG emissions and was therefore not considered suitable for development of an ERF methodology.

Nitrous oxide emissions increased following repeated applications to a horticultural rotation with highest losses (2 kg N2O-N ha-1 yr-1) after two annual applications of raw chicken manure. Composted manure reduced N2O emissions by up to 45% when applied at rates designed to match plant demand. Furthermore, by accounting for the nitrogen supplied through mineralisation of the manure products, the application of synthetic fertiliser could be reduced by up to 38% without a yield penalty. Overall the supply chain reduction in GHG emissions associated with composted manure was 68-97%. The application of composted instead of raw manures to the field would be an effective ERF methodology.

Johannes Biala

Equipped with degrees in Agriculture and Environmental Science, Johannes Biala has worked in organics recycling, composting and the use of recycled organics products for 30 years. He has extensive experience as consultant and researcher in all key areas of the organics recycling supply chain, including collection and processing of urban organic residues and the use of recycled organic products in agriculture & horticulture. Late last year he managed to establish the Centre for Recycling of Organic Waste and Nutrients as part of UQ’s School of Agricultural and Food Sciences.

27 March 2018

Cameron Jackson & Matthew Mulliss – Queensland Urban Utilities

QUU’s nutrient management approach, and nutrient recovery opportunities/challenges


Queensland Urban Utilities provides water and wastewater services to 1.4 million people in south-east Queensland. As the region grows, Queensland Urban Utilities faces the long-term challenge of improving environmental outcomes from wastewater discharges into the region's waterways and Moreton Bay, while maintaining downward pressure on its cost to serve. Concurrently, Queensland Urban Utilities is exploring the potential of sewage as a source of valuable resources to produce saleable products to offset operational costs. In this session, Queensland Urban Utilities’ long-term nutrient management plan will be discussed together with current opportunities, potential benefits and challenges of nutrient recovery and beneficial use. Queensland Urban Utilities’ nutrient management plan comprises a set of traditional, green infrastructure and market-based responses to efficiently improve the ecological health of waterways in south-east Queensland. Nutrient recovery opportunities such as biosolids, struvite, electrodialysis and source separated urine, will play an increasingly important role in delivering this plan.

15 May 2018

Ian Levitt

Fabrication of a Slow Release Nitrification Inhibitor through Extrusion Processing

Ian Levitt is a PhD student looking into the development of novel controlled release agrichemical formulations using biodegradable polymers, predominantly using polyhydroxyalkanoates (PHAs). He attained his integrated Bachelor and Masters of Chemical and Biological Engineering degree at The University of Queensland in 2014.


Nitrogen (N) loss from agricultural land represents inefficiencies for the farmer and significant environmental impacts through N pollution of fresh and coastal waters, potent greenhouse gas emissions, and volatilisation of other reactive N compounds. In Queensland, protecting our Great Barrier Reef (GBR) from nutrient dumping has environmental, social and economic benefits. More than 80,000 tonnes of N enters the GBR lagoon annually.

Only 30-50% of N applied to sugarcane land in QLD is accounted for in crop biomass, with the balance lost to the environment. N stabilising agents are commonly used in conjunction with N fertilisers to slow the biological oxidation of ammonium to nitrate in the soil. However, efficacy has only been proven for temperate climates. The persistence of nitrification inhibitors in agricultural soils diminishes rapidly with increasing temperature. Consequently, their use in tropical agriculture is limited. Dicyandiamide (DCD) has been studied as a fertiliser stabiliser for more than 50 years for temperate and sub-tropical regions, however, efficacy is limited at elevated temperatures. The encapsulation and controlled release of DCD may prevent exposure of the molecule to degradation mechanisms until it is in the soil profile.

Here, poly(3 hydroxybutyrate co 3 hydroxyvalerate) (PHBV) has been investigated as a biodegradable matrix for the encapsulation of DCD. Industrially relevant extrusion processing was used to fabricate DCD-PHBV pellets at a loading of 25 wt% DCD. Release profiles were monitored in water, sand and soil at 30 oC. Release curves show significant surface wash (30-45%) within the first week, with a sustained release rate of 2 10 μg from 3 weeks out to 20 weeks. After 20 weeks ~40-57% of the DCD was mobilised.

We have demonstrated the ability to initially load the soil with a significant proportion of the encapsulated DCD, followed by a very gradual mobilisation of the DCD into the soil.


Global Change Institute (Blg 20) The University of Qld St Lucia

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