Soil sampling technology
We adapt the type of sampling as well as the tools used exactly to your problem. This is because the examination of soil samples allows statements to be made regarding soil quality, soil contamination, soil life, the expected behavior of a soil and its suitability for a particular purpose. We would be happy to help you find the right strategy and sampling technology for your application.
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Things to know
Challenges in soil sampling
For every type of soil investigation it is true that the result of the investigation can only be as good as the quality of the samples. However, the different questions and investigation possibilities place different demands on a soil sample. The quality can therefore not be evaluated in general, but depends on how well the necessary requirements are met. In general, however, the sample must be representative. This means that it should reflect the property to be investigated in a way that is typical for the location.
For this, the "site" must first be defined more precisely. For which scale should the obtained results be representative? From single measuring points, soil profiles and pits over fields or forest areas up to entire regions, planned investigation areas can have quite different dimensions. Inhomogeneities within this investigation area have to be considered during sampling. Especially sample size, number of samples and the distribution of sample sites over the investigation area depend on this.
Furthermore, the property to be investigated must be preserved during sampling. In the case of pure mass observations and chemical analyses, only the constituent to be examined must remain unaffected in the soil. The structure of the soil is not decisive here. The samples can be taken disturbed.
However, interactions between the materials of the sampling equipment (drills, storage vessels, etc.) and the substance to be analyzed must be taken into account and avoided. For soil physical investigations and questions concerning water and air balance, the chemical properties of the material can be largely disregarded. Here, however, it is crucial to preserve the soil structure during sampling and until analysis. The soil sample must be obtained undisturbed.
Typical aims for Soil sampling
- Receiving information about soil structure / the soil stratification
- Information on nutrient and humus content of a soil
- Information on occurrence, frequency, and activity of soil organisms including pests
- pH-value determination of the soil
- Determination of the particle size distribution for the basic characterization of a soil
- Determination of parameters of the water and air balance (for example pore volume, hydraulic and pneumatic conductivity, retention curve)
- Determination of mechanical soil parameters to evaluate the stability of the soil (e.g. pressure sensitivity or shearing resistance)
- Chemical analysis for the detection of harmful and hazardous substances in soil
The possibilities for the analysis of soil samples are very diverse. Accordingly diverse is the application range for soil sampling within the scientific and economical sector.
- Soil science incl. soil ecology
- Monitoring, evaluation and remediation of legacies of pollution
- Building sector
Things to know about soil sampling
Disturbed soil samples
The original stratification and structure of the soil is destroyed during removal. The representativeness of the material is the leading quality criterion.
This type of sampling is generally sufficient for chemical investigations, to determine the current water content and to determine the grain size distribution.
Soil material is retrieved with a shovel, a chisel or an auger (drill) and transferred into a transport vessel or a bag without taking into account the soil structure. Mixed samples can be taken over different depths or over larger areas in order to take account of the influence of inhomogeneities.
Undisturbed soil samples
The original stratification and structure of the soil is retained in the sample. The lowest possible influence on the soil structure during extraction is a decisive quality criterion.
This is particularly necessary for soil-physical investigations, as well as for investigations concerning the water and nutrient budget.
Removal of soil samples with drills while maintaining the stratification. Depending on the technology, the scale and quality of a soil drilling core sample can be very different. The soil structure can be influenced to some extent by the compaction, wall rubbing, shearing forces, etc., during sampling, so that the sample is no longer undisturbed. Material transfer can also lead to disturbances in the original layer sequence.
Sampling of soil samples of specific volume with a substantial preservation of the soil structure. The soil samples are separated from the surrounding soil by means of a soil core sample ring driven into the soil and subsequently transported in the closed puncture cylinders as gently as possible. The volume of the driven ring leads to the compaction of the soil in the edge region. The lower the wall thickness of the sample ring and the greater the volume of the soil sample, the lower the influence of the compression. The rings are usually driven by a hammer into the ground. The resulting vibrations can lead to changes in the sample structure. For very dry, hard grounds, it is not possible to retrieve samples since the sampling ring can not be driven in.
Removal of soil columns of specific diameter and specific length with minimal influence on the soil structure. Unlike sampling cylinders, the sampling vessel is not hammered into the ground. The soil column is cut free and the vessel takes it in without deformation. This way the compaction on the edges as well as the influence of the vibration caused by the driving impact on the structure is prevented. Further soil columns can be obtained in significantly larger scales than sample ring samples. It is also possible to take samples of very dry, hard soils.