Soil Moisture Tensiometer

A tensiometer is a tool for monitoring soil moisture conditions in agriculture. Tensiometers can be easily read by irrigators in the field and operate without electricity.

Tensiometers measure soil moisture in units of negative pressure, also known as tension. Tension is a measure of the force that plant roots must exert to pull water from soil pores (Figure 2). Large pores (macropores) hold water with less force than small pores (micropores). As plants extract moisture from the soil, water is first taken from the largest pores. As the soil dries, more force is required to pull water from smaller pores. High tension values mean that the soil is becoming dry, the plant experiences more water stress and growth slows.