Making soil collars

You can make your own soil collars with materials that are widely available in the United States. In other countries you may need to special order materials.

10 cm collars

The 10 cm (4 inch) collars are made from thin-walled polyvinyl chloride (PVC) sewer pipe. The pipe must have an inside diameter of 10 cm (3.930 inches) minimum and an outside diameter of 11.4 cm (4.5 inches) maximum. Cut a section approximately 8.9 cm (3.5 inches) or longer, depending on requirements for your measurement. Bevel the bottom edge with a grinder or coarse file.

20 cm collars

The 20 cm (8 inch) collars are constructed from thick-walled 8 inch SDR 35 PVC pipe. Use a grinder, coarse file, or an extremely large lathe to bevel the bottom edge to an angle of 24°.