Soil ring sampLER & Soil Rings

VSI Soil Sample Rings. Soil rings are manufactured from stainless steel to minimise impact on the sample, other materials are available on request. One side of the rings can be tapered (outwards) to facilitate insertion into the soil (when using the 'direct' type 1 sampler and soil rings longer than the sampler head). High density polyethylene lids (top and bottom) are available for many standard ring diameters to provide secure sample storage during transport. Soil core sample rings are available in various diameters and height (see Soil Ring Calculator below), and with or without bevelling. Soil sample rings sets are sold in sets of 10 ring; sets can include a transport container. Request a custom quote for soil ring sets today. 

Images for illustration purposes only, design subject to change without notice

To help you select the appropriate soil ring dimensions for your application, a brief overview of soil ring inner diameters and heights, as well as the corresponding sample area (cm2) and volume (cm3) is given in the table below. Custom soil ring diameter and height effects on samples soil volumes etc. can be determined with the Soil Ring Configurator. Actual soil ring dimensions' availability depends on source materials -  please inquire.

SOIL RING Configurator

Soil ring samplers are commonly used to collect soil samples for bulk density determination and other physiochemical soil analyses requiring known sample volumes and uncompressed samples. 

Equipment needed: 

• (Sharp-edged) ring (stainless steel) of known volume, e.g 100-200 cm3 (ca. 5 cm diameter, 5 or 10 cm height; see above for table/calculator). 
• Soil ring sampler to gently push / hammer the sample rings into the soil.
• Soil knife, putty knife or similar to remove the ring and any excess soil adhering to it.
• Either 2 lids for the soil ring or plastic bags, pot. rubber bands to secure the lids or bag, and marker pen for labeling sample numbers (alternatively, metal soil rings may be numbered permanently).
• Transport box or backpack for equipment and soil samples.

Example sampling procedure:

1. Sample (in the vicinity of) your research plots, but avoid any area where soil compaction may have occurred from other sampling activities or where future research is planned. See also brief overview on soil sampling techniques and key references.
2. i) Remove the coarse litter layer and possibly any organic layer and gently insert the first ring directly from the soil surface to sample the 0-5 or 0-10 cm depth layer; if the sampler could not be inserted smoothly (e.g. due to woody roots or stones), try again nearby. ii) Alternatively, excavate a small soil pit with a preferably smooth profile wall and then gently insert the soil ring from the side to sample either at defined horizons or depths. For depth profiles larger than the diameter of your soil ring sampler (e.g. 10-20 and 20-30 cm depth layers), consider placing the centre of the soil rings at 15 and 25 cm depth respectively. For thinner layers, consider coring from the top after removing overlying horizons. In any case, it is key to avoid compaction of soil samples during sampling.
3. Excavate the soil from around the ring and cut the soil below the base of the ring from the side, e.g. using a pallet knife. Cutting a straight surface at the base of the soil ring is particularly important when using the direct soil ring sampler (type 1) to sample the correct volume, while the cutting shoe of the type 2-soil ring corer holds some 'extra soil' which can be removed once the soil ring is removed from the corer 'sleeve'.
4. Remove excess soil from above the ring using a knife: first remove excess soil from above the sample, then place a cover/lid over the ring and turn it upside down to remove soil adhering to the ring and cut a smooth surface at the bottom of the ring. Either transport the cleaned ring to the laboratory (using lids) or remove all soil from the ring into a plastic bag and seal immediately. To stay at field moisture, rings should be additionally wrapped in bags, avoiding too much headspace for moisture to condensate on. 

Here are some best practices to consider when planning your soil ring sampling campaign:

• Appropriate soil ring size: The size of the soil ring sampler should be selected based on the soil texture and depth of the sampling site. If the soil has a high rock skeleton content, a larger ring sampler may be required to ensure that the sample is collected intact. Smaller rings may be better suited to sample narrower soil horizons or more detailed depth increments (e.g. 5 cm steps). In general, larger diameter samplers may reduce the degree of sample compression due to the reduced friction on inner ring surfaces. 
• Sample handling: It is important to handle the soil sample carefully to avoid compaction or alteration of the sample. Samples can be carefully removed from the sampler and transferred to a container for transport to the laboratory, or sample rings can be sealed with lids for transport. Make sure the soil rings are 100% filled on top and bottom, do not lose soil belonging to the soil volume sampled while emptying the soil rings! For deeper / shallower soil sampling campaigns, where compression is less of an issue or time is of the essence, a correction factor may be calculated from the height of soil sampled and the depth of the hole in the soil.
• Sampling depth: Soil ring samplers should be inserted into the soil at a consistent depth to ensure samples are representative. Carefully consider the depth of organic topsoil layers when sampling vertically - consider to sample organic and minerals soil layer separately. Often horizontal sampling within the walls of soil pits provides the most representative data on soil density depth profiles. Choose sample rings which fit the dimensions of the morphometric horizons you want to sample. 
• Repeat measurements: To improve the accuracy of bulk density determination, several samples should be taken and measured from the same area. A minimum of three replicates should be sampled per depth / horizon for any interpretation.
• In the lab - determine moisture content, non-fine soil constituents: Soil moisture content has a significant effect on bulk density measurement. It is thus important to determine the soil moisture content in the laboratory (on a subsample immediately when processed, to minimize drying). Similarly, it is important to determine the volume and weight of stones and plant organs in your sample - allowing to determine the fine soil content within the soil ring.

For other tasks, consider the Soil Corer (deep sampling with often minor compression) or the Topsoil & Root Corer (ideal for humus and root sampling), respectively. See below for a small selection of articles / manuals providing more detailed descriptions on soil sampling procedures.

• Al-Shammary, A. A. G., Kouzani, A. Z., Kaynak, A., Khoo, S. Y., Norton, M., & Gates, W. (2018). Soil bulk density estimation methods: A review. Pedosphere, 28(4), 581-596.
• Grossman, R. B., & Reinsch, T. G. (2002). 2.1 Bulk density and linear extensibility. Methods of soil analysis: Part 4 physical methods, 5, 201-228.
• Hao, X., Ball, B. C., Culley, J. L. B., Carter, M. R., & Parkin, G. W. (2008). Soil density and porosity. Soil sampling and methods of analysis, 2, 179-196.
• Heuscher, S. A., Brandt, C. C., & Jardine, P. M. (2005). Using soil physical and chemical properties to estimate bulk density. Soil Science Society of America Journal, 69(1), 51-56.
• Lee, J., Hopmans, J. W., Rolston, D. E., Baer, S. G., & Six, J. (2009). Determining soil carbon stock changes: simple bulk density corrections fail. Agriculture, Ecosystems & Environment, 134(3-4), 251-256.
• Solgi, A., Naghdi, R., Labelle, E. R., Tsioras, P. A., & Salehi, A. (2018). Comparison of sampling methods used to evaluate forest soil bulk density. Croatian Journal of Forest Engineering: Journal for Theory and Application of Forestry Engineering, 39(2), 247-254.