Quick questions on Carbon farming and emissions reduction explained: HSC Agriculture Climate Challenge

Agriculture is a major source of Australia's greenhouse gases, dominated by two non-carbon-dioxide gases. Methane comes mainly from enteric fermentation, the digestion of fibre by microbes in the rumen of cattle and sheep, plus methane from manure and from rice paddies. Nitrous oxide, a very potent gas, comes from nitrogen fertiliser and from nitrogen cycling in soils, especially when soils are wet and waterlogged. Carbon dioxide comes from fuel use, from clearing vegetation, and from the loss of soil organic carbon under continuous cultivation.

Emissions can be cut on the source side. For methane, feed additives such as the seaweed-derived compound and other inhibitors suppress rumen methane production, while improving herd efficiency (faster growth, better fertility, fewer unproductive animals) lowers methane per kilogram of product. For nitrous oxide, matching nitrogen fertiliser to crop demand using the four Rs, using nitrification inhibitors, and avoiding waterlogged soils all reduce losses. For carbon dioxide, fuel-efficient and reduced-tillage practices and avoiding land clearing help.

Australia rewards verified abatement and sequestration through carbon credits. Under the Australian Carbon Credit Unit scheme, farmers who adopt approved methods, such as soil carbon, environmental plantings, avoided clearing or herd-efficiency methods, can earn tradeable credits sold to government or to companies offsetting their emissions. This creates a new income stream, but it requires measurement, verification, long-term commitment to maintain the stored carbon (permanence), and careful judgement of whether the carbon income exceeds the cost and the production trade-offs.