|Urea-coal blends and plant trial for P-humate blends|
|By Azita Kargosha and Biplob Saha, PhD Candidates, Monash University; Supervised by Assoc. Prof. Tony Patti, Monash University, School of Chemistry|
|Global use of chemical fertiliser, specifically nitrogen, phosphorus and potassium (N, P and K), is rising steadily, driven largely by China, the United States and India. By 2030 fertiliser applications in these regions are expected to increase by about 50%. However, much of the fertiliser applied to crops is not utilised by the plants and is wasted. For example, during the period 1950–1990, the application of nitrogen fertiliser increased by 15 times, whereas the amount of N utilised by plants increased by only three times. The remaining fertiliser was lost through a variety of mechanisms, including leaching, volatilisation, and breakdown by microorganisms, as well as chemical processes such as hydrolysis and precipitation.|
The excess fertiliser entering the environment leads to problems such as algal blooms, contamination of groundwater and release of ammonia and nitrous oxide into the atmosphere. Nitrous oxide is a potent greenhouse gas and causes acid rain and the destruction of atmospheric ozone. Repeated applications of chemical fertilisers can alter the soil composition, increasing the salinity and the concentration of heavy metals.
The most widely used nitrogen fertiliser, urea, is synthesised from ammonia which, in turn, is produced from hydrogen (from natural gas) and nitrogen (from the air). Phosphorus fertilisers, on the other hand, cannot be economically synthesised from chemical precursors but must be mined. Phosphorus is thus a non-renewable resource and is in short supply. Globally, it is expected that peak phosphorus production from mining will occur at around 2030. It is therefore important to find more efficient ways to use chemical fertilisers, to make the most of vital but increasingly scarce resources, and to minimise their harmful impacts on the environment.
Two BCIA-funded PhD students at Monash University, Mrs Azita Kargosha (Figure 1) and Mr Biplob Saha (Figure 2), are investigating the potential of brown coal to increase the efficiency and availability of N and P fertilisers.
|These two projects build on the observation that the charged ionic groups within brown coal, or on coal-derived humates, can bind with N and P fertilisers, making them available in slow-release form. |
Biplob Saha is investigating combination products containing N fertilisers, while Azita Kargosha is evaluating the performance of superphosphate-based blends. Both students are part of the Soil Carbon Group within the School of Chemistry at Monash University, under the supervision of Associate Professor Tony Patti. Azita Kargosha is nearing the completion of her PhD project, while Biplob Saha (Figure 2) has completed the first year of his project.
The students have been assisted in their work by two local companies, Torreco and Feeco Australia. Torreco uses a torrefaction process to heat the brown coal briefly in an oxygen-deficient atmosphere, which makes the coal very dry and brittle, and thus easier to grind and granulate. Feeco has expertise in granulation technology, and has produced small batches of granules containing blends of brown coal / humates and chemical fertilisers, for testing at Monash University.
The two complementary projects have a focus on understanding how brown coal influences the fundamental interactions between the fertiliser, soil and plant. This fundamental understanding is essential for optimisation of the performance of coal-based fertilisers, but has not previously been studied in any detailed.
By supporting the training of these two PhD students, BCIA is helping to create opportunities for new, environmentally-friendly products from Victorian brown coal. The specialised skills that are being developed will underpin the development of the new commercial fertiliser products described elsewhere in this newsletter.
|Figure 1: Azita Kargosha analysing soil samples.|
|Figure 2: Biplob Saha with the columns used to monitor fertiliser behaviour in soil.|