Carbon Footprint – Australia

Reducing greenhouse gas emissions through sustainable clothing

A significant body of research and extension work has been invested in tackling greenhouse gas emissions in the Australian production system. Best practice and technical support has been developed across a number of areas that contribute to greenhouse gas emissions, including carbon farming, energy efficiency, nitrogen efficiency, measuring energy usage and water use efficiency.

Australian cotton farmers continue to reduce greenhouse gas emissions and improve the land’s ability to store more carbon through practices and innovations including:

• Maximising the efficiency of major inputs used in cotton growing, such as energy and nitrogen, by optimising irrigation pump performance and using fuel-efficient farm machinery
• Using alternative sources of nitrogen, i.e., the use of legume rotation crops which fix nitrogen in the soil
• Implementing other practices to improve soil health including using controlled traffic and minimum-tillage systems
• Further minimising machinery operations (and therefore fuel use) of spraying (through industry-wide use of herbicide-tolerant cotton), and during harvest (through broad scale changes in machinery to replace multiple machines with one)
• Using renewable and alternative energy sources and fuels such as solar panels to power irrigation pumps, and biofuels
• Conserving and managing areas of native vegetation and riparian areas on farm, which are valuable carbon stores

On-farm case studies have indicated that adoption of conservation tillage has reduced energy costs and greenhouse emissions by 12 percent since 2000. Improved water use efficiency, as well as improving yield, also reduces greenhouse gas emissions per unit of production through reduced pumping (lower energy use) and waterlogging (which can lead to methane emissions).

Focus on nitrogen efficiency

The principal types of greenhouse gas emissions on mixed cotton farming enterprises include carbon dioxide, methane and nitrous oxide. Nitrogen fertilisers are a major source of greenhouse gas emissions, particularly nitrous oxide, and the Australian cotton industry continues to invest in research, demonstration trials and decision support tools focused on improving nitrogen use efficiency.

Greenhouse gas inventory tools for cotton and mixed farming properties are available online, including carbon calculators and management tools.

Nitrous oxide emissions are being measured on irrigated cotton farms, and emissions can be reduced through modifying farming practices such as reducing tillage, minimising use of groundwater (which requires more pumping), improving rainfall soil-moisture storage, rotation crops, optimising irrigation design and scheduling, and adjusting fertiliser placement deeper in the soil.

To improve nitrogen use, a number of industry-wide strategies are being implemented, including:

• Crop nutrition research
• Training for advisors and farmers
• An industry-wide project to monitor and demonstrate best practice

The industry’s myBMP (Best Management Practices) program includes specific strategies for improving nitrogen use efficiency, including:

• Soil testing is undertaken at an appropriate time to assess nitrogen levels and fertiliser requirements
• A Nitrogen Fertiliser Management Plan has been developed and implemented
• Plant monitoring is undertaken during the season to assess crop nitrogen status and used to adjust crop nutrient program
• Nitrogen Use Efficiency (NUE) is determined for each field using Nitrogen Fertiliser Use Efficiency (NFUE) calculation; this is recorded each year and monitored over time
• Crop rotation systems that include legumes to fix nitrogen effectively are adopted when practical
• Nitrogen Use Efficiency (NUE) is calculated and field performance is assessed against long-term farm performance

Preparing for climate change

Not only is the cotton industry trying to mitigate its contribution and further develop sustainable clothing, but researchers are also determined to help the industry adapt to climate change. So that appropriate adaptation strategies can be developed, they’re investigating the impact on soil health and function from extreme events like extended droughts and intense rain, which are predicted to occur more frequently.

Future climates for cotton growing regions are being modeled to better understand the potential impact on the key growth phases of the cotton crop, and to again identify appropriate adaptation strategies. Other researchers are growing cotton in large climate-controlled tents under elevated temperature and carbon dioxide levels, to understand how they affect crop growth and test irrigation strategies that maximize water use efficiency.