Greenhouse gas emissions

Gases produced by human activity are affecting the global climate. Agriculture plays a role in this. But with the rising global human population, how can farmers increase food production to meet demands while simultaneously cutting back on greenhouse gas emissions?

Efficient and responsible use of fertiliser and related products can help ensure food security and economic wellbeing while contributing to reducing New Zealand's overall greenhouse gas emissions.

New Zealand's emissions profile

As part of ratifying the Paris agreement on climate change, New Zealand has set a target of reducing our emissions by 30% below 2005 levels by 2030.

New Zealand's emissions profile is unique amongst OECD countries. In 2016, 85% of New Zealand's electricity was produced from renewable sources, while just 11% of New Zealand's greenhouse gas emissions were from fossil fuels used for manufacturing processes. In contrast, primary industry generates almost half of New Zealand's total greenhouse gas emissions. It also generates more than half of New Zealand's export income.

There is no silver bullet for reducing agricultural emissions, which presents some real challenges for meeting New Zealand's emissions reduction target while maintaining a strong, vibrant economy.

Where does fertiliser fit in?

The contribution of fertiliser to greenhouse gases comes mainly from nitrogen. Applying nitrogen fertiliser to land results in nitrous oxide emissions, because of the natural biological soil processes.

In New Zealand, more than 5% of agricultural emissions are from nitrogen fertilisers while the application of lime to soils results in another 1.4% of agricultural emissions.

Greenhouse gas emissions from the manufacture of urea fertiliser in New Zealand is accounted for under existing Emissions Trading Scheme commitments for industrial processors.

Solutions

We need new technologies that increase productivity while using less fertiliser, to reduce greenhouse gas emissions from fertiliser. Precision agriculture technologies have an important role to play. There are also products that help reduce nitrous oxide emissions from soil. These products affect the transformation pathways for nitrogen in the soil by reducing the release of ammonia gas or by reducing the conversion of ammonia to nitrate.

Urease inhibitors are increasingly used in New Zealand to reduce the volatilisation of nitrogen. These have a minor overall impact on greenhouse gas emissions. Nitrification inhibitors have wider applications than just fertiliser emissions. They have the potential to significantly reduce nitrous oxide emissions from livestock urine patches. These are not currently used in this context in New Zealand but could be in future if applications can be appropriately targeted and are cost effective.

The Fertiliser Association was represented on the Biological Emissions Reference Group in 2018. This Group brought together a wide range of agricultural, horticultural and farming stakeholders to collaborate with Government and build a solid evidence base. The Group commissioned several research reports to fill information gaps.

Other practical measures include:

• Overseer: This nutrient budgeting tool examines nutrient use and movements within a farm. Understanding the nutrient cycle and the impact of different farm management practices on the nutrient losses can help farmers to manage greenhouse gas emissions.
• Nutrient Management Adviser Certification Programme: This programme is about ensuring farmers get consistent nutrient management advice of the highest standard. NMACP has also introduced a certification endorsement for greenhouse gases. This will be available to Certified Nutrient Management Advisers who complete Massey University's three-day course 'An introduction to New Zealand's Agricultural Green House Gas Emissions and Management'. Course content includes the latest in greenhouse gas mitigation policy and research for pastoral and arable farming.
• Research: The fertiliser industry invests in research aimed at efficient and responsible use of nutrients, including reducing greenhouse gas emissions.