Eight Footprint Farms, totalling approximately 900ha, are currently being tested for soil carbon. It’s an exciting time and the farmers are eager to see the results.

Soil carbon samples had been taken last year in different areas of the farms, but as we learn more about soil carbon sampling, we have decided to take detailed samples.

It is unclear if and how farmers will be paid for carbon in the future and if the samples will actually result in farmers being rewarded for that carbon if an increase occurs.

However, if we don’t have the information, we cannot prove anything and this is why it is important to invest in programmes and projects like the Footprint Farmers.

The information gathered will also be provided to the Signpost Programme to increase the level of data in the national project.

There is still a lot to learn about soil carbon sampling for carbon trading or payments and, looking at reports, there is a lot of conflicting information out there.

The basics say that the sample should be taken to at least 30cm and Teagasc is currently taking samples every 4ha.

We have divided farms into sampling areas of 4ha or less. Some samples might be 1ha and some might be the maximum area of 4ha. This is because we will not join one field with another when it could be managed differently.

For example, one field may have had farmyard manure or slurry applied and the other field may not have received it.

Sampling is quite intense and all sampling points are tracked via GPS

Once the maps were divided up appropriately, it was time to hand over the task of sampling.

Sampling to 30cm is much more laborious than sampling to the usual 10cm, so a hydraulic sampler is used, where possible.

Sampling is quite intense and all sampling points are tracked via GPS.

Over the past few weeks and into the coming week or so, Mark Connolly from Farmteam Precision Agriculture, along with his colleagues, are busy using both an automated sampler and a hand sampler on farms across the country taking these samples.

Lab

The samples are then sent to the lab for analysis. Many labs that carry out regular soil sampling are now carrying out soil carbon testing. Samples generally cost in the region of €32/sample (excluding VAT) so testing is expensive.

It is essential that farmers also get the lab to test for bulk density. This tells you the density of the soil and allows you to calculate the amount of carbon in the soil as a result. For example, if there were 3,000t of soil in 1ha to a depth of 30cm and the soil carbon percentage was 3%, then there would be 90t of carbon/ha in the soil.

We previously published soil carbon results from three different soil types on Tullamore Farm sampled to a depth of 30cm. This showed that there was 144kg of carbon/ha in a field in permanent pasture adjoining the farmyard, which would have stock on it regularly and would receive farmyard manure.

On land converted from tillage to grass in 2017, there was just 63kg/ha of carbon and, in some of the wetter land across the road from the farmyard in permanent pasture, there was 101kg/ha of carbon.

It is important to note that soil carbon sampling can be carried out at any time of the year, provided you can travel on the ground.

Soil carbon levels change slowly over time. If you were sampling for phosphorus and potassium, you would sample before fertiliser is applied as if fertiliser was applied it would not give a correct reading.

• Total hectares on farms: 899ha.
• Farms: eight.
• Farm types: Dairy, beef, sheep and tillage.
• Sampling depth: 30cm.
• Maximum sampling area: 4ha.
• Plants can take in carbon from the atmosphere and that carbon can then be stored in the soil.