Most of our experiments are carried on plants grown in a soilless media in standard four-inch pots.
Soil moisture is determined by tensiometers.
Certain tensiometers are fitted with a pressure transducer instead of a gauge. A computer or datalogger can then read this signal. The voltage is measured by a CR10X data-logging system manufactured by Campbell Scientific. Readings are taken every 10 seconds, and at 15-minute intervals the datalogger will average and store the information from each tensiometer. A solenoid valve will not allow water to pass through it unless an electrical current is supplied to the valve.