Soil Carbon Check

The intensity of soil sampling needed to find a significant increase in SOC includes, but is not limited to:

1. Area (field/plot- or farm- or district/region/group-level).
2. Land use (arable or grassland).
3. Current soil organic carbon content.
4. Anticipated increase.
5. Single or double soil sampling.

Soil Carbon Check is a soil test that provides unique insight into the actual amount of CO₂ stored in the soil, and the development of CO₂ capture over time. Soil Carbon Check is based on an organic matter determination with NIRS. Soil Carbon Check adds depth to the existing C-determination on Fertilizer Manager.

The report of Soil Carbon Check is supported by the Carbon Calculator. This handy calculator makes it possible to determine the effect on carbon capture of a crop, green manure crop or animal manure or compost. The advice that follows makes possible to optimize the carbon management for the own situation.

More information

Empower Innovations in Routine Soil Testing. Reijneveld, J.A. et al. Agronomy 2022, 12, 191. https://doi.org/10.3390

Eurofins Agro does not produce carbon credits; we provide reliable tests that can be used by certifying parties.

The build-up of organic matter in soil takes time and requires the continuous attention of the farmer/grower. Soil management and mineralization by soil life have a great effect on carbon capture. Climatic conditions, temperature and precipitation are also very influential. Annual monitoring provides insight into the actual state of the soil; measuring and re-measuring the soil carbon status should lead to a significant increase in CO₂ storage. When a Soil Carbon Check is performed yearly, improvement can be proved much sooner. Moreover, chain partners in the agri-food sector require up-to-date figures on the condition of the soil. Only with up-to-date data is it possible to claim and prove sustainable land use.

Carbon enters the soil via degrading organic matter from root exudates (substances in the rhizosphere that are secreted by the roots of living plants and microbially modified products of these substances). It is therefore best to sample the soil layer in which most roots are located, or the plough layer (as this is mixed with organic matter). We advise a depth of 30 cm, if possible.

Yes, this is possible. However, it is hard to see an increase when organic matter is already high.

Grasslands are very apt for storing soil organic carbon; permanent grasslands sequester carbon particularly easily. However, arable land is also suitable for storing carbon and although in arable farming systems sequestering carbon can be challenging, there is very high potential.

CO₂ is captured in the soil organic material as carbon. Plants capture CO₂ from the air through photosynthesis into organic matter; therefore, leaves, wood and roots form an endless storage vessel for CO₂. Micro-organisms are also a major source of soil organic material; however, soil life (fungi, bacteria, small insects etc.) also breaks down organic material. This causes CO₂ to be released again. This is known as the carbon cycle.

Soil organic matter is the collective term for all the material found in the soil that comes from microorganisms, plants and animals. Organic matter consists largely of complex molecules of carbon (C), oxygen (O) and hydrogen (H). It also contains other organic substances (e.g. proteins and amino acids) which include nitrogen (N), phosphorus (P) and sulfur (S).

As a guideline, soil organic carbon makes up about 50% of the organic matter, however, this percentage varies widely (between 30 and 70%). The actual soil organic carbon content depends on factors such as the origin of the organic matter and the type of soil.

There are several ways to capture CO₂ in soil. The best method is dependent on the type of farm. A few suggestions are:

• Improve/adapt crop rotation. Crops such as maize, potatoes and onions take up a lot of nutrients from the soil and leave little crop residue. Crops like wheat, barley, and grasses form a lot of organic matter and thus contribute to organic matter accumulation.
• Provide additional organic matter with animal manure or compost. In the circular economy, the use of compost will become increasingly important.
• Sow a green manure/cover crop to ensure a growing crop is on the field as much as possible. There are several types of green manure and their contribution to organic matter varies. The choice of green manure depends on the land, soil health and climate. 
• Leave crop residues (roots, stubble etc.) on the land as much as possible after cultivation. This contributes to soil health and the build-up of organic matter and prevents erosion.
• Ensure optimal crop growth. Fertilization that is tailored to the crop and the soil, as well as sufficient water, are needed. Soil and crop analyses will give you indispensable insight into optimize fertilization and ensure that the crop receives exactly the right amount of nutrients during cultivation.

Organic matter affects biological, chemical and physical soil fertility. Organic matter provides nitrogen (N), sulphur (S) and other nutrients to crops by being released during the decomposition of organic matter. Nutrients like potassium (K), magnesium (Mg) and calcium (Ca) are loosely bound to organic molecules, which are weakly negatively electrically charged. They can thus hold positively charged ions such as ammonium (NH4+) or potassium (K+) to the CEC.

Organic matter retains moisture. Plots with higher organic matter content are therefore less susceptible to drought and can more effectively ‘capture’ water from rainfall. It is food for soil organisms, therefore not only important for mineralization, but also for the resilience of the soil. Finally, organic matter improves the workability of the soil.

Most organic matter is stable, however, organic matter can disappear through decomposition by soil life and it is re-supplemented by the input of manure, compost and crop residues for example. The difference between supply and degradation determines whether the content is in balance. If the decomposition is higher than the supply, the organic matter content decreases and vice versa. 

Effective organic matter is the part of the organic matter that remains in the soil one year after application of crop residues, manure or compost. In the first year after application a large part of the organic matter disappears because it is easily degradable. The contribution of this fraction to the content in the soil is therefore quite small. The contribution of the more stable fraction is greater.

The report of Soil Carbon Check is supported by the Carbon Calculator. This handy calculator makes it possible to determine the effect that a crop, green manure/cover crop, animal manure or compost has on carbon capture. The advice that follows allows you to optimize carbon management in accordance with the specifics of an individual farm.

Use the link or QR-code on your report to open the Carbon Calculator. The Carbon Calculator will then take your latest personal soil carbon data. Use this data to optimize your choice of crop or which manure/green manure/compost to apply on your fields.

The Carbon Calculator also shows the amount of additional carbon you have stored, in tonnes per hectare, and therefore how many carbon credits you may be able to claim.

Carbon Calculator

CO₂ is captured in the soil organic material as carbon. Plants capture CO₂ from the air through photosynthesis into organic matter, therefore, leaves, wood and roots form an endless storage vessel for CO₂. Micro-organisms are also a major source of soil organic material, however, soil life (fungi, bacteria, small insects etc.) also breaks down organic material. This causes CO₂ to be released again and this is known as the carbon cycle.

CO₂ capture in organic matter therefore depends on the type of organic matter: stable organic matter contains more carbon than fresh organic matter. The activity of the soil life is important for the degree of degradation. Carbon Check provides insight into the amount of carbon captured.

At the COP21 (Paris) a 4 per 1000 increase was anticipated; so an annual increase of 0.4% per year.  On average an increase of 2 ton CO2 can be expected (depending on among others weather conditions and management). 

To calculate climate impact, soil carbon capture is converted to CO₂. To do this, a factor of 44/12 = 3.67 is used (mole mass CO₂/mole mass C). This means that 1 ton of soil carbon (as part of soil organic matter) matter corresponds to 3.67 tons of CO₂ capture.

Organic matter has several important functions in the soil. It is one of the most important indicators of soil health. Organic matter is food for all soil organisms. Because no light penetrates into the soil, soil organisms cannot use sunlight for photosynthesis as an energy source. This means all soil organisms depend on organic matter for their energy and food supply. Organic matter contributes to nutrient delivery, moisture and air management and soil structure.

One crop is not the other when it comes to the contribution to effective organic matter. More about green manures.

As it gets warmer on earth, the breakdown of organic matter in the soil will increase. It is therefore important to keep a finger on the pulse and perform regular Soil Carbon Check.