Following
on the theme of soil (moisture) sensors, this blog is concentrating on soil
temperature. At this time of the year
(mid-August) soil temperature is or has become the most important factor
influencing irrigation (and to a lesser degree fertiliser application). Just like soil moisture, if you don’t get the
installation or measurement point this right you will never get any decent data
and never be able to utilise the soil temperature measurements with any
confidence. There are three key
requirements for soil temperature measurement:
a)
Ensure
any sensor is centred at 10cm depth or the measurement is taken at 10cm;
b)
Ensure
the sensor or measurement taken is under the crop/pasture (not in a bare patch
for example); and
c)
Temperature
is measured at 9am (and not 9am daylight saving time).
Why
is 10cm depth and 9am so important? Crop
production models use the 9am 10cm soil temperature as a key input
parameter. If the soil temperature is
not above the base temperature at 9am then production will be affected.
In the
northern east coast of the North Island (Gisborne area) temperatures have
already peaked above the base temperature for pasture at 15°C and have been
above 10°C for 6 days in August.
In the
South Island (in the example mid Canterbury) temperatures have not even
approached the 10°C base temperature.
So whether
you have soil moisture sensors installed that also measure soil temperature or
you use a $50 manual gauge, measure soil temperature from now to assist and
guide the need to irrigate.
For more information on anything in this blog please contact HydroServices
