Soil Moisture Meters

Soil moisture meters are devices used to measure the percentage of water found in potting or ground soil. They determine whether crops require watering or if their soil is over-saturated and require a drying out period to maintain the health of the plants. Soil moisture meters are not expensive and can be found at home and garden shops. Typical readouts on the meters range from 1 to 10 or give a color indication of red, yellow, or green. These readings correspond with the humidity of the soil being measured.

How do Soil Moisture Meters Use Electrical Resistance Blocks?

Soil moisture meters are usually portable sensors that are inserted into the soil to measure a physical property related to its dampness. The most common sensor used for this purpose is the electrical resistance block that operates on the principle that since water is an electricity conductor, soil with high water content will have low electrical resistance. The two types of blocks that are used for moisture meters are granular matrix sensors and gypsum blocks. Gypsum blocks are usually buried in soil for regular readings to be taken. These readings are taken from either wired data loggers, or in limited cases, hand held monitoring devices. Gypsum blocks are significantly used in commercial farming.

Soil Moisture Meters and Thermal Dissipation Blocks

Soil moisture meters can also use thermal dissipation blocks that contain heaters and temperature sensors. The blocks are porous, ceramic, and work on the premise that wet objects heat slower than dry ones. These sensors are normally buried in the soil and commercial farmers use them.

Soil Moisture Meters and Tensiometers

A tensiometer is a tube filled with water that has a porous ceramic tip and is inserted into soil. The device has a vacuum gauge at the end of it that extrudes from the ground and displays the water tension measurement. These soil moisture meters are easy to install, but are found to work best in soil with a zero to 80 centibar rating. Tensiometers require regular servicing because their tubes have to be filled with water. These are most commonly found in orchards and cultivated fields.