Horticultural weather stations are usually used with MetWatch software which include algorithms for calculating the risks of various diseases based on meteorlogical observations. Doing this, they can use the actual weather history from their own properties rather than relying on weather reports at sites with different microclimates.
Equipment and sensors used for horticultural monitoring do not often require the high specifications required at research stations or in harsh environments.
The CR200, the brains of the station, takes readings every three seconds from the attached meteorological sensors. These are stored and used to calcluate minimums, maximum, averages & totals and applied calculations such as potential evapotranspiration and soil moisture defecit. Data is stored hourly and daily at 0900, 1200 and 0000 hours in different identifiable arrays. The datalogger also controls the switching on/off of sensors and the telemetry options.
Combination air temperature and humidity probe measuring 10-90% RH. Accuracy +/-3% & +/-0.4C. Used within a RS-50Y naturally aspirated radiation shield on an extended arm from the mast.
The worlds, longest soil moisture sensor, and Kiwi designed and manufactured. Aquaflex measures soil moisture in volumetric moisture content and averages readings over its 3m length, a 6 litre volume of soil, overcoming traditional problems of soil variability. The sensor is used to measure soil moisture in the top 350 mm of the soil profile (where most pasture roots are) by placing the sensor ribbon in a sloping trench from just below the surface to 350mm depth. This allows the average water content to be measured over the profile so a water balance can be calculated.
Mid-range rugged, wind speed sensors. The Hall Effect anemometer outputs two pulses each time it rotates. These are counted by the datalogger and converted to wind speed and/or wind run. It has a starting threshold of 1.8m/s and 2.5% accuracy over the full range. The W200 has a voltage output corresponding to 0-360 degress and a starting threshold of 1m/s.
Texas Instuments 0.2mm Tipping Bucket Rain Gauge
International standard tipping bucket rain gauge with 0.1mm tip.
This sensor is calibrated to measure the shortwave radiation reaching the Earth's surface. The evaporation of water from soil and the transpiration of water from leaves are partly determined by the intensity of this shortwave radiation, which is measured in Joules m-2 s-1 or Watts m-2.
Telemetry & Data Retrieval
Data is retrieved via telephone telemetry using a modem connected to the datalogger and landline. Data can be retrieved from any PC running PC208W or PC208.
Power
The low power requirements of the CR200 mean that the station can easily be powered by solar panel. We use a Solarex 50W solar panel and regulator. This recharges the 12VDC battery used by the datalogger. Alternatively, the station battery is charged using a mains powered charger. This is the cheapest option for stations with a power supply close by. This recharges the 12VDC battery used by the datalogger.
Structural
Horticultural stations would normally be mounted on a 2 or 3 m mast. The datalogger, battery and telemetry components are all enclosed within the sealed stainless steel enclosure.
