Using an onsite weather station to manage plant micro-climate
By David Hunt, GIA Smart Farming Project Officer
A close up of the portable electronic weather station. (Image: Liam Southam-Rogers, AHR)
We all know that growing healthy marketable plants need three main resources, sunlight, food (nutrients) and water. How the plants use these resources is dependent on the growing environment and the physiological stresses the plant experiences.
Managing and maintaining an optimum growing environment can be difficult if you do not have a closed climate-controlled greenhouse. Plants grown in semi-closed structures or open outdoor areas are more affected by the seasonal variation of the local weather, and extreme weather events can leave plants stressed and more prone to pest and disease damage. Being able to monitor the local weather conditions and adjust production processes is one way of reducing the impact weather variation have on the plants.
For years nursery managers have relied upon weather data and forecasts provided by the Bureau of Meteorology (BoM) to determine the daily irrigation schedule, frost prevention, fertiliser applications, or spray schedules, which is a valid and proven management method. These weather forecasts have been developed from years of data collection and modern modelling programs to provide primary producers with an accurate representation of the weather conditions. The limitation is that BoM weather data is drawn from weather stations across a wide geographical range, which are often considerable distances from production nursery locations. This data is averaged or extrapolated to provide a general weather forecast, but in some geographical locations, or under protective structures, the forecasts do not represent the actual climate conditions or evapotranspiration (ET) rates influencing plant growth. This can lead to decisions being made that might not suit a specific situation.
A wireless portable weather station installed within a shade house used to monitor the growing environment. (Image: Liam Southam-Rogers, AHR)
Anyone who has installed hail netting or a shade house over a growing area will know how this immediately changes the micro-climate compared to the full sun areas. One way to ensure production decisions are based on the actual growing environment influencing the plants is to incorporate a simple weather station onsite or even within a shade house. Some might question the reasoning of installing a weather station inside a protective structure or under shade cloth, but this will provide a real-time representation of the actual growing environment or micro-climate affecting plant growth and production decisions.
Most weather stations can provide the basic parameters such as temperature, relative humidity, barometric pressure, dew point, wind speed and direction, solar radiation, and precipitation. There are many types of weather stations on the market and it does not need to be the most expensive for a business to benefit. However, a good weather station will calculate the ET in mm/hr following the UN FAO56 method, which is the recognised international standard used for calculating ET and adjusting an irrigation schedule. This is one of the most accurate ways to match your irrigation regime to actual real time water loss from containers, especially in multi-species growing areas.
Research and field trials have shown that if an irrigation system has been installed to best management practice, adjusting the irrigation schedule to the daily ET can improve water use efficiency by 20% to 40%1,. This will also help to reduce pump energy use, reduce nutrient leaching, improve root growth and plant health. Determining the ET from local weather conditions will provide a more accurate adjustment value that matches the micro-climate of the plants.
Another benefit of on-site weather stations relates to the recording of prevailing weather conditions during the application of pesticides. The nursery industry takes the responsibility of applying pesticides seriously and has set guidelines to maximise pesticide use efficiency whilst limiting any negative impact on the environment. Using the data provided by a weather station, nursery managers can combine forecasts, local readings and historical records to demonstrate compliance with best practice guidelines and their commitment to environmental sustainability.
As part of the Smart Farming Partnerships project funded under the National Landcare program, Greenlife Industry Australia (GIA) and Hort Innovation have installed a state-of-the-art weather station under shade cloth at Golden Grove, the Smart Farming projects’ production nursery. This provides a constant live feed of weather data to the operations control tower in the office. At a glance, the business owner knows exactly what conditions the plants are experiencing and can adjust irrigation rates and frequency, or direct staff to different tasks based on this constant feedback. An added benefit of this real-time weather data will be the automatic recording of the weather conditions into the spray diary for pesticide application, which will then be uploaded to the audit management system (AMS) to satisfy NIASA and EcoHort accreditation requirements.
A snapshot of weather conditions from the control tower at the Smart Farming project's production nursery. (screen shot composite by David Hunt)