Horizontal soil sampler

Designed by Yoav Bashan

Environmental Microbiology Group, Northwestern Center for Biological
Research (CIBNOR), La Paz, B.C.S., Mexico

Horizontal soil sampler in a wheat field

A horizontal soil test tube sampler and the related technique for horizontal quantitative determination of soil rhizosphere microorganisms are described. It is easy to construct, requires no special maintenance, and was successful in field trials over the last 20 years for collecting samples.

The tool can be adapted to other types of soil research, such as surface root distribution and distribution of soil surface contaminants. To the best of my knowledge, this test tube sampler has no counterpart among tools for soil surface sampling.

The method is based on the principle of inserting sterile tubes into the ground in the sampled area and analyzing microflora, using either traditional microbiological methods on culture medium or by molecular techniques, for determining microbial populations and mapping of the soil surface (<10 cm depth).

The tool was design to overcome two basic problems with common manual insertion of test tubes to the soil: (i) sterile, disposable plastic tubes are fragile and frequently break, especially in dry soil and can result in injury to the field personnel; (ii) sampling sites at each plot are never exactly repeatable, which leads to different sizes of the area sampled; these variations increase the sampling error whenever replicated plots are examined.

The main advantages of the horizontal soil sampler are:
  1. It is light, small, portable, rust-free, easily arranged on the soil surface, and its operation requires little strength from field personnel. Each sampling takes less than 10 minutes for the full procedure. Many samples can be retrieved each day.
  2. The tool gives precise, repeatable, and equally-spaced distribution of tubes over relatively large area.
  3. The tubes are standard, sterile, disposable, cheap, and no contaminant can disturb the number of microorganisms counted by this method.
  4. Sampling is possible even under dense foliage, the damage to plants is minimal, and the method can be used in small experimental field plots.
  5. The tool does not require maintenance, does not need cleaning or lubrication, and the parts do not wear away.
  6. The soil sample is completely sterile, and the tool does not need to be sterilized.
  7. A minor disadvantage of the tool is that in heavy muddy soil the outer surface of the tube may be covered with mud, which has to be removed before taking the tubes to laboratory analyses.

This website contains technical description of the tool and its accessory, a technical diagram, the procedure for extracting samples under field conditions, photos (in a PowerPoint presentation, 1 MB), and a PDF publication describing the entire procedure and equipment.

The soil sampler that we use was constructed by a team led by Eng. J. Wolowelsky at the workshop of the Weizmann Institute of Science in Israel.