Many farmers are now looking to better understand their soil health – and a newly launched practical guide to assessing soil carbon could be a good place to start.

Produced by Duchy College, Plymouth University, Rothamsted Research and the Farm Carbon Toolkit, the online guide lists and answers key questions for on-farm monitoring of soil carbon and associated indicators of soil health.

Carbon sequestration plays a key part in climate change mitigation, but soil carbon’s importance goes beyond sequestering as much as possible, explained Rothamsted research scientist Andy Neal: “What’s much more important are the co-benefits of getting organic matter into soil – organic matter affects how much water and nutrients the soil can store, and can limit the carbon footprint."

Read more: Soil variations could undermine carbon scheme

The guide includes tips on the timing of soil sampling – the important thing is to avoid sampling after cultivation, particularly if the ground has been ploughed. Fields should be left to settle after cultivation for at least three months.

Farmers should also sample at the same time each year because seasonality can affect results

When it comes to sample location, it’s best to select fields which represent the variation across the farm, including differences in soil texture, cropping and management. The guide recommends at least five sample points although 15 is preferable. Samples can be aggregated but only on a field or zone basis and they must be well mixed before bagging.

In terms of equipment, a soil auger is the best implement for the job – but digging a hole and removing soil by hand is fine. Clean buckets and sandwich bags are also necessary for collecting the samples.

Farmers should send the samples off as soon as possible, although up to two weeks’ delay is acceptable if they are refrigerated – as this slows the organic matter breakdown.

• The practical guide is now available on the Farm Carbon Toolkit website: Launch of Guide on Monitoring Soil Carbon - Farm Carbon Toolkit