ARE YOU GETTING THE MOST FROM YOUR SOIL? Recent interest in carbon trading and the Government’s Net Zero by 2050 target has led to an increase in enquiries at NRM laboratories relating to Soil Carbon, Organic Matter and the link between them. Agriculture can play a significant role in carbon sequestration, with soil providing a huge carbon sink. Understanding the soil and what percentage is made up of carbon plays a key part in being able to effectively manage and increase the carbon stock percentage. The launch of the Environment Land Management Scheme (ELMS) is likely to create more reasons for landowners and farmers to understand their carbon stock. Although the details are not confirmed, it is expected that Soil Health and Carbon stocks will form part of the scheme.
In response to the increased interest, NRM laboratories have developed a comprehensive package which provides an accurate assessment of the carbon stored in soils, applicable to both grassland and arable systems. CarbonCheck provides not just an organic carbon stock figure but also a range of other useful parameters. It uses a combination of individually tested parameters and calculations to determine carbon figures and provides users with a report to enable action to be taken and comparisons to be made. It is recommended that sampling should be carried out regularly to monitor changes in soil carbon stock levels, ideally at the same time of year to reduce sampling variation. The Bulk Density of a soil gives a good indication of how well plant roots can
grow and explore the soil for nutrients, and how easily air and water can move within the soil profile. The Bulk Density of the soil is used to calculate the Organic Carbon Stock. This is carried out using the ‘disturbed scoop’ method. This is different to the undisturbed core method. The scoop method was chosen over alternative methods due to the positive supporting evidence regarding this method. Sampling Depth and Stone Content details are provided by the sampler on the sample paperwork. This allows the laboratory to determine the soil coverage per square meter. Providing this background data ensures a more accurate assessment of the carbon stock in the soil.
Inorganic Carbon also known as Soil Inorganic Carbon (SIC) comprises of carbonates and bicarbonates which are abundant in chalky soils. The calcium carbonate content of the soil is determined from the SIC and means we can assess how calcareous the soil is. Total Carbon % is determined using the combustion method, which is comparable with the Dumas method. Total carbon measures both inorganic and organic carbon forms in the soil. Organic Carbon is then calculated by removing the Inorganic Carbon figure from the total Carbon figure. Also known as Soil Organic Carbon (SOC), it is the carbon component of soil organic matter. This diverse group of carbonbased compounds originates from the
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94 DIRECT DRILLER MAGAZINE
ISSUE 13 | APRIL 2021
