Which tool is commonly used for testing soil moisture content?

The soil moisture meter is specifically designed to measure the moisture content in the soil, making it the most appropriate tool for this purpose. This device typically uses electrical resistance or capacitance to determine the amount of water held in the soil, giving instant readings that help gauge whether irrigation or additional watering is necessary. Accurate moisture readings are crucial for maintaining optimal conditions for plant growth, making the soil moisture meter indispensable for landscape professionals.

Other tools mentioned have different primary functions. The subsurface plow is used for tilling and turning the soil but does not measure moisture. A soil thermometer is intended to assess soil temperature rather than moisture levels, which is also essential but serves a different purpose. Lastly, a hydrometer is used to measure the specific gravity of liquids, primarily in contexts like determining soil texture in water, not for direct moisture content in soil. Thus, the soil moisture meter is uniquely suited for testing soil moisture content efficiently and accurately.