Field-Ready Methods for Casting Soil Biopores

Preserving biopore geometry is an important first step in evaluating its effect on the movement of water, air, and chemical substances through the soil. This is usually accomplished by making and extracting a cast of the biopore. To prevent damage to or distortion of the cast, sufficiently large, continuous biopores (such as those made by burrowing insects) may be preserved and excavated in the field. Soil casting presents a number of unique challenges caused by the size and/or complexity of the biopore combined with the trouble of casting into the soil material itself. Techniques may fail due to a lack of infiltration caused by the volume or tortuosity of the biopore, or due to penetration of the casting material into the soil matrix. I compiled and reviewed methods for preserving biopores in the field and evaluated them based on preservation quality, time, cost, and practicality. Overall, I recommend zinc casting due to its cost, preservation quality, and durability, although dental plaster casting is suitable for most purposes and has the advantage of preserving specimens trapped inside the cast. Additionally, I present instructions for a lightweight and cost-effective propane powered field kiln for casting biopores using zinc or aluminum scrap