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The weather station has four 'soil temperature sensors and one soil moisture probe
Low numbers indicate more moisture. The readings are of 'soil-water suction' in centibars.
1 Metre Deep Sensor
The main role of this sensor is to give an indication of deep freezing of the soil in winter. When the ground is frozen at depth it will give
negative readings. However, in spring when presumably the ground is frozen below the sensor but melting is taking place, we saw a long period where the temperature
was at or close to zero. So zero usually means there is frost in the ground either above or blow the sensor. Remember frost varies over short distance according to
the amount of sun that a site receives and the thermal properties of the soil (of which water content is an important factor).
20 cm Deep Temperature sensor
This is the appoximate planting depth of crops such as potatoes.
4 cm Deep Temperature sensor
TYupical depth for sowing many seeds. The shallow depth means that it will vary greatly between night and day (check max and min values).
Surface Temperature sensor
During the day the data generated by this probe is meaningless because it is affected by solar radiation directly heating the probe. However, at night it picks up temperature on the surface,
which can be several degrees lower that the temperature probe in the main weather station. Thus the ground sensor will often detect a frost (sub zero temperature) where there is a positive
reading from the station (about 8 feet up a pole). This temperature difference taken after nightfall generally indicates radiative heat loss and in many situations will warn of the likelyhood of frosts.
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