Name a tool commonly used for soil testing.

The soil auger is commonly used for soil testing because it is specifically designed to collect samples of soil from various depths, allowing for an analysis of soil composition and structure. This tool enables technicians to extract cylindrical samples of the soil, which can then be examined for pH levels, nutrient content, organic matter, and other essential characteristics.

By removing a core sample, the soil auger facilitates a thorough assessment of the soil's physical and chemical properties, which is vital for making informed decisions about planting, fertilization, and soil amendments. This level of detail is crucial for managing soil health and ensuring optimal growing conditions for plants.

While the other tools mentioned can have specific uses in gardening or landscaping, they do not directly serve the primary purpose of comprehensive soil testing in the same way that a soil auger does.