Nitrification inhibitors (enhanced fertiliser)
Enhanced efficiency fertilisers (EEFs) incorporating inhibitors have been shown to reduce nitrous oxide emissions by up to 80 per cent. Their potential can be easily accommodated in estimating emissions reduction by using a lower emissions factor compared to urea or other traditional fertilisers1.
Nitrification inhibitors are used to stabilise Nitrogen (N) in soil, avoiding nitrate leaching and reducing denitrification. Common nitrification inhibitors include DMPP (3,4 dimethylpyrazole-phosphate) and DCD (Dicycandiamide) and are effective in irrigated and non-irrigated cropping and pasture systems, particularly when applied in wet soil conditions2.
For improved nutrient use efficiency and emissions reduction benefit, Fertiliser Australia encourage combined considerations of best nutrient stewardship and precision agriculture tools3. The agronomic benefits are often small and dependent on soil type and seasonal conditions. However, the environmental benefits from reducing GHG emissions can be significant.
Out of Scope:
Enhanced efficiency fertilisers also include products with urease inhibitors and polymer-coated urea (PCU). Both aim to improve N use in environments with high risks of leaching or volatilisation. Although they can have an indirect impact on emissions reduction, there is currently less quantitative evidence available. Their impact on N use efficiency and emissions reduction are variable and depend on design chemistry and environment. These products may be reconsidered as the evidence base and use guidelines improve.
Activity requirements:
- Nitrification-inhibitor-based EEFs must be purchased from manufacturers that are registered members of Fertiliser Australia.
- Fertilisers must have been treated in Australia with the inhibitor, and not imported as a treated product due to limited shelf life.
- Use must comply with Fertiliser Australia Code of practice, including attention to crop and livestock withholding periods.
- Current examples of nitrification-inhibitor based EEFs can be found in a recent Fertiliser Australia publication. In a rapidly changing market, up-to-date information should be sought from your agronomic advisor.
Primary emissions benefit:
- Avoided emissions from lower emissions product
- Reduced emissions from improved fertiliser use
Co-benefits:
- Off-site environmental impact reduced
- Possible increased crop production
Potential barriers:
- Inconsistent production benefit depending on condition
Implementation
When considering a transition from traditional fertilisers to enhanced efficiency fertilisers, there are several key considerations and steps to ensure successful adoption. These include:
- Understand EEF options including whether nitrification inhibitors are suited to your production system. The EEF market is rapidly changing, including regulation and application guidance. Seek up-to-date industry advise from registered advisors.
- Understand soil types amd crop needs to develop a plan based on nutrient budgeting and stewardship principles, alongside understanding of your local risks of leaching, denitrification, and volatilisation.
- Consult with agronomists with EEF experience to gain appropriate advice into the benefits and challenges of EEFs in your farming operation, and insight into how to optimise your strategy.
- Evaluate the cost-benefit ratio considering factors such as up-front costs, application rates, potential yield gains, and performance under regional climate variations.
- Continuous monitoring, evaluation, and learning based on common indicators of nitrogen use efficiency (NUE) to inform, adjust, and optimise application strategies.
Activities:
- Agronomic services and soil testing – to define application appropriate to crop needs
- Purchase of fertiliser treated with nitrification inhibitor (DMPP, DCD based chemistry) from a manufacturer registered with Fertiliser Australia.
Monitoring:
- Proof of eligible purchases (invoices)
- Annual enterprise emissions baseline and estimation of emissions reduction
Stacking compatibility:
- Variable Rate (VR) fertiliser
- Pasture regeneration – with attention to livestock withholding periods
1 Nitrogen Fertiliser Use & Greenhouse Gases. An Australian Assessment: Challenges and Opportunities. Fertiliser Australia, November 2023.
2 Nitrogen Fertiliser Use & Greenhouse Gases. An Australian Assessment: Challenges and Opportunities. Fertiliser Australia, November 2023.
3 Nitrogen Fertiliser Use & Greenhouse Gases. An Australian Assessment: Challenges and Opportunities. Fertiliser Australia, November 2023.