GAINS in fertiliser technology, both in application and in manufacturing will be critical in allowing Australian grain growers to lower their carbon emissions according to a report commissioned by the Grains Research and Development Corporation.
The Australian Grains Baseline and Mitigation Assessment report, compiled by CSIRO, found that in the longer term, green hydrogen and ammonia, which has the scope for markedly lower emissions, would be a big winner in allowing Aussie grain growers to cut emissions.
However, the report found the technologies were still in their infancy, with most planned production of green hydrogen and ammonia in Australia not expected to become fully operational until around 2030.
The report said estimates suggest that globally green ammonia could become cost-competitive in niche markets around 2030, but more general cost competitiveness may take as long as 2050 to achieve.
It will be worthwhile, with reductions of emissions of up to 50 per cent found in some of the report's modelling, but it is not something that will be a big help in any 2030 carbon emission reduction targets.
In the short-term, CSIRO research Maartje Sevenster said a key finding of this study is that improved fertiliser application can result in a decrease in greenhouse gas (GHG) intensity per tonne grain of up to 20pc while increasing production.
Based on estimated uptake by 2030, an overall reduction in GHG intensity of around 15pc may be feasible, while at the same time increasing production by 30-40pc, Dr Sevenster said.
However, while she said there could be a drop in emissions intensity, an overall drop in absolute emissions while increasing production would be difficult, with a significant reduction of embedded emissions of fertilisers and other inputs needed.
Nitrogen application will be a big area for growers to try and cut emissions.
Dr Sevenster said in the report several different nitrogen application strategies were used, from industry standard right up to a "MaxN" standard where all fertiliser decisions were made in perfect harmony to maximise yield.
"It can be slightly difficult with some crops to match between biomass and grain yield but this is the theoretical goal we wanted to model."
"It avoids under and over application, not limiting N for crop growth but not allow surplus levels of N to build up in the soil and be prone to losses into the atmosphere."
Dr Sevenster said there were a number of ways farmers could move towards peak N efficiency, including variable rate fertiliser applications, improved N budgeting and timings and the use slow or controlled release products.
She said in all regions, improved N management is seen to bring about lower emissions intensity because the increases in grain production exceed the increases in the associated GHG emissions.
Looking forward to the availability of economically affordable fertiliser inputs such as ammonia and hydrogen, Dr Sevenster said the report modelling replaced natural gas as a feedstock and used renewably-fuelled electricity instead, which saw falls of up to 90pc in production emissions.
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