Carbon is the buzzword at the minute – from carbon emissions to storage and sequestration, everyone seems to have something to say on it. It’s time we got the figures.
Soil carbon samples taken on Tullamore Farm in March revealed how much carbon is stored in the farm’s soil.
Farms sequester and store carbon every day. We regularly hear about agricultural emissions, but we do not hear about the emissions that agriculture is accounting for by taking in carbon through hedgerows, trees and crops and storing carbon in the soil.
In the coming years, this carbon will hopefully play an important role in the calculation of farm emissions, but at present, regulations prevent this carbon sequestration from being used to offset agricultural emissions – a major flaw.
However, it is important that we begin to measure this carbon and gather data on how much carbon farms are sequestering.
Farms which are sequestering more carbon than they are producing could then trade their carbon credits and gain recognition for farming in an environmentally friendly way.
In time, these credits could be traded with other farms or with the wider industry. Ag Climatise – the Department of Agriculture’s roadmap to climate-neutral farming – outlines carbon trading as a possibility in the future.
Preparing for the future
The agricultural sector needs to be ready for when credits can be traded and emissions can be offset.
Tullamore Farm is preparing for the future of farming. These carbon samples are the start of the farm’s journey into carbon measurement and are part of a wider project being undertaken by the Irish Farmers Journal, which will be revealed in the coming weeks.
Taking the carbon samples
We first outlined three different areas on the farm that we would test for carbon storage. These areas were chosen based on soil types and previous management. All fields are in grassland and most has been reseeded within the past 10 years.
We picked a field beside the farmyard which would receive regular applications of animal manures.
The second sample area was taken in Cloona, which is away from the farmyard. This land was previously in tillage and is some of the drier land on the farm.
The final sample was across the road from the farmyard on a different soil type again. This soil is known as a ‘Moorey’ soil. It is dark in colour and again is not as free draining as some of the other land on the farm.
The samples were taken as any other sample would be taken – in a ‘W’ pattern, giving a representative sample and avoiding unusual areas where farmyard manure was tipped, for example.
The samples were taken from the top 30cm of the soil. This is the recommended depth from the IPCC (Intergovernmental Panel on Climate Change) for soil carbon sampling.
As was expected, the field beside the farmyard had the highest carbon stocks, with 144t C/ha. The field across the road from the farmyard on wetter land had a carbon stock of 101t C/ha in the 0-30cm soil horizon.
The field out of tillage was significantly lower than both samples taken from the land near the farmyard, with 63t C/ha. High-yielding, continuous cereal crops grown with little being returned to the soil can lead to low stocks.
All soils have room for improvement, but there is a huge opportunity to increase carbon stocks on the land out of tillage.
Improving soil carbon levels
Soil carbon levels would need to be monitored on an ongoing basis and improvement will be essential. Building up soil carbon is a slow process.
Measures like straw incorporation, the application of farmyard manure or slurry and the growing of cover crops can all help to build carbon levels, as well as animals cycling nutrients.
However, there is huge potential in our soils to store more carbon and this carbon can be stored deep in the soil horizon, depending on the soil type.
Research from Teagasc on heavy soils showed that soil carbon levels were higher than first thought and that there was potential to store significantly more carbon than was currently being stored in the soil.