Pack soil around the block to ensure good capillary action between the sensor and the soil. Calibrate blocks in each field to ensure accurate prediction. Moisture blocks are not recommended for sandy soils. Tensiometers are well adapted to sandier soils. This is directly related to the tension required for plant roots to extract water from the soil.
Tensiometers consist of a tube with a porous ceramic cup at one end and a gauge at the other.
To install, place in the soil to the depth of plant rooting. Fill with water. As the soil dries, the tension increases, indicating water is more difficult to extract from the soil. Although tensiometers indicate when you should begin to irrigate, they do not indicate how much water you should apply. Missouri irrigation scheduling charts Extension centers in Missouri can provide irrigation scheduling charts for soybeans and other crops.