Soil Health Solutions

Soil Crop Monitor

I just applied fertiliser, can I perform a Soil Crop Monitor?

For foliar feeding, this is not a problem. The plant material is washed before analysis, so only nutrients taken up by the plant are measured. If you have applied a fertiliser to the soil, we suggest waiting at least 2 weeks. In the soil analysis, all plant available nutrients are measured. This means that the nutrients from the fertiliser are also accounted for. If the fertiliser has not been completely dissolved, it is possible that high nutrient values will be found.

Why do you advise to sample less than 1 ha for Soil Crop Monitor?

When samples are taken on a larger area, the heterogeneity of the field can influence the results, and make them less reliable. By sampling a small area, this problem is much smaller. It is best to sample on a representative location, which is secured by GPS. The next sample can then be taken at the exact same location. Another option is to perform a Soil Crop Monitor in higher and lower performance areas of the field. The results can then give insight into the reason behind the differences.

I applied plenty of nitrogen (N) fertiliser, but I don’t see high mineral N values in the soil on my report. How is that possible?

It is possible that the crop has taken up the nitrogen (N) very efficiently. You can check this by looking at the N uptake by the crop, which is also shown on the report. If this is not the case, the N can be leached. If there has been a very wet period, the N can also be volatilized. Another possibility is that the N has been immobilized (taken up) by the soil life. It will then become available at a laterstage.

Why are my mineral N values so high?

Sometimes mineral N values in the soil can be higher than expected during the season. In a long period without precipitation, plants have difficulty taking up nutrients from the soil because there is not enough moisture in the soil. However, there can be enough moisture in the soil to sustain mineralisation by the soil life. Another possibility is recent fertilisation, or rain after a long period of drought (then mineralisation will increase).

Why is it important to know the emergence date?

After the emergence date, the crop will grow and take up nutrients. By combining the sampling date with the emergence date and linking this with the total nutrient need of the crop, the advice is calculated.

Why is it important to report the expected yield?

For the advice, we assume a standard yield for the crop. However, if you know your yield will deviate from that (higher or lower), we can adjust the advice. This will result in an optimal fertilisation for your crop.

Soil Life Monitor

What is the 'PLFA method'?

The biological parameters of Soil Life Monitor are analyzed using the PLFA method. PLFA stands for phospholipid fatty acids. These fatty acids occur in the cell membranes of living organisms. Different groups of organisms have unique compositions of PLFAs. By measuring and quantifying PLFAs, it is possible to obtain a fingerprint of the soil food web. For example, the cell membranes of fungi consist of different PLFAs than those found in bacteria. The PLFAs present are measured and quantified using gas chromatography-mass spectrometry (GC-MS).

How does the NIR analysis work?

Eurofins Agro measures PLFAs using near-infrared spectroscopy (NIRS): a quick, innovative, and reliable method. NIRS analysis uses PLFA GC-MS as the wet chemistry reference method. By analyzing many samples – both with wet chemistry and with NIRS – the NIRS analysis is calibrated to optimally measure PLFAs in soil samples.

What is the Soil Life Monitor used for?

Soil Life Monitor responds to the widespread demand for a better understanding of soil life and biological soil quality. As the number of permitted crop protection products declines and awareness of the importance of soil life grows, many sectors are paying more attention to soil life.

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When is the best time to take sample for Soil Life Monitor?

The best time to take a sample for Soil Life Monitor depends on the purpose of the analysis. For plots being monitored over time, the best time to take samples is at roughly the same time every year and under similar conditions each time. Soil life is generally more active in the growing season under warm, moist conditions. In winter, soil life activity slows down. In addition, very dry conditions can kill off or largely inactivate soil life.

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What is the sampling protocol for Soil Life Monitor?

The best way to take a Soil Life Monitor sample depends on the substrate.

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How rapidly do phospholipid fatty acids (PLFAs) degrade once an organism dies?

PLFAs are known to degrade rapidly and are therefore indicative of living microorganisms. However, the rate at which the fatty acids degrade depends on environmental factors, particularly temperature. 

Soil Life Monitor

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Can the PLFA method also identify soil life at species level?

No, the PLFA method can only distinguish between groups of microorganisms such as actinomycetes and arbuscular mycorrhizae. PLFA analysis provides a fingerprint of the soil food web. Plating methods and DNA techniques are more suitable for identifying specific species.

Soil Life Monitor

What are the target values based on?

The target values indicate how the sample scores compare with similar soils or matrices and are based on percentiles of samples taken in practice. The target values of outdoor and greenhouse soil samples are furthermore corrected based on their organic matter content. The target values of soils that are poor in organic matter are lower and lie closer together than soils that are rich in organic matter.

Soil Life Monitor

What are actinomycetes?

Actinomycetes are a special type of bacteria. They form thread-like filaments similar to hyphae, but are not fungi, as they have no cell nucleus and their cell walls contain no cellulose or chitin.

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What are arbuscular mycorrhizae?

Arbuscular mycorrhizae (AM) are fungi which can establish a symbiotic association with around 80% of all plant species. The fungi grow in and around the roots and deliver nutrients and water to the crop in exchange for sugars. The larger the mycelium (the network of fungal threads, or hyphae) around the roots of a crop, the more nutrients, such as nitrate and phosphate, the plant can absorb.

Crops that establish very little or no symbiotic association with AM are plants from the Cruciferae (e.g. brassicas) and Chenopodiaceae (e.g. spinach and beetroot) families.

What types of mycorrhizae are measured with the Soil Life Monitor?

The PLFA analysis provides insights into the biomass of the active mycelium (network of fungal threads or hyphae) of arbuscular mycorrhizae in the soil. The fatty acid 16:1ω5 is used for this purpose. 

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What are protozoa?

Protozoa are single-celled microorganisms which contain a nucleus (eukaryotes). The most important function of protozoa is to make nutrients available to the crop by 'grazing' on micro-organisms (particularly bacteria). Protozoan activity is highly dependent on the presence of moisture in the soil. The action radius of protozoa is limited to water films and water-filled pores. Small pores can protect bacteria against protozoan grazing.

What does the gram+/gram- ratio indicate?

Bacteria can be divided into two different groups: gram-negative (gram-) and gram-positive (gram+). Gram-positive bacteria are generally larger than gram-negative bacteria and can form spores. This makes them more resistant to drought and water stress. Gram-positive dominant populations (>1) are more common at the beginning of the growing season and balance out again when the soil conditions become more favorable. Gram-negative dominant populations (<1) are often associated with other forms of stress, such as ploughing and the use of pesticides. Gram-negative bacteria can tolerate these types of disturbance better because they have an outer membrane.

What does the fungal-to-bacterial ratio indicate, and how is it calculated?

The fungal-to-bacterial ratio indicates the ratio between the total fungal biomass and the total bacterial biomass (expressed in g C/kg soil). The ratio can also be used as an indicator for the extent of disturbance. In general, undisturbed ecosystems have a higher fungal-to-bacterial ratio than disturbed systems. Biological and low-input systems have a higher fungal-to-bacterial ratio than conventional, enriched systems. Forms of disturbance such as tillage, removal of crop residues and grazing cause this ratio to drop.

What is the Shannon-Wiener index?

The Shannon-Wiener index (SWI) is a measurement of the ecological diversity of the groups of organisms that occur in the soil. The index uses the number of species and their abundance as input. The lowest value of the SWI is 0 (only 1 species present), and the maximum is dependent on the number of species when they are all present in the same abundance. The index is based on the six groups that are measured with Soil Life Monitor analysis: gram +, gram -, actinomycetes, saprophytes, mycorrhizae and protozoa.

Why is the total number of fungi and bacteria in the soil not the same as the total microbial biomass?

Microbial biomass is a quantified total of a large number of fatty acids. Fungi and bacteria make up the largest proportion of this but do not contain the entire microbial biomass. The unit of the parameters measured is mg PLFA/kg soil. The biomass of fungi, bacteria and microbial biomass in mg C/kg soil is calculated using a conversion factor known from literature.

How long does a Soil Life Monitor analysis take?

The maximum duration of an SoilMonitor analysis is three weeks after arrival of the sample at the Eurofins Agro lab in Wageningen.

Soil Carbon Check

What is the recommended sampling intensity?

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.
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What is new in Soil Carbon Check?

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.

How can I get carbon credits?

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

Why should you perform Soil Carbon Check annually?

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.

What is the best sampling depth for a Soil Carbon Check?

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.

Can you still perform a Soil Carbon Check when organic matter levels are high, like on peat soils?

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

Can a Soil Carbon Check be used on both arable land and grassland?

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.

How does the soil store CO2?

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 (fungibacteria, small insects etc.) also breaks down organic material. This causes CO2 to be released again. This is known as the carbon cycle.

What is the relation between soil organic matter and soil organic carbon?

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.

How can I increase CO2 capture in the 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.

How does organic matter contribute to soil health?

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.

What is a soil organic matter balance?

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. 

What is effective organic matter?

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.

What is the Carbon Calculator?

The report of Soil Carbon Check is supported by the Carbon CalculatorThis 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

How much CO2 can the soil capture?

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 (fungibacteria, 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). 

How do you calculate how much CO2 is captured in organic matter?

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.

What role does organic matter play in the soil?

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.

Which crops should I sow to improve soil organic matter?

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

What is the effect of global warming on soil carbon capture?

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.

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