Choosing sensors for nursery production – questions you should ask before buying

26 September 2024

By David Hunt, Smart Farming Project Officer

Smart technologies or AgriTech has slowly been developing for decades, but now with the addition of Artificial Intelligence (AI), machine learning, remote access, and cloud-based data analysis with predictive services these technologies are getting smarter, and more confusing. So how do you choose the right sensor system for your business?

Choosing technologies and service providers is dependant on the type of production systems used, what you want the technology to tell you, and what works for your business. There are several questions that should be asked before buying any sensors to help identify the level of sensor sophistication needed and reduce the purchase and ongoing service costs.

1) Are you using smart technology to Automate or Monitor a production system?

This question will have the greatest influence on the cost of the sensor system and service provider you choose. Automating a production system requires highly accurate and reliable sensors to ensure the data truly represents the crop or process. The sensors must be suitable for the growing environment, have a backup power supply, and a default program that will continue to operate independently if the connection to the main control computer fails.

Monitoring a production system is cheaper as the level of sensor sophistication and maintenance are reduced. Data accuracy is still important but a failed monitoring sensor does not stop the production system from working. Consider monitoring a system before full automation to develop an understanding of the daily fluctuations in the data, and identify any critical issues that may be a problem for automation.

2) Is the sensor data for management decisions, certification reporting, or environmental performance monitoring?

If the sensor data is for monitoring production processes to support production decisions, choose a sensor system that you are comfortable with and has easy to understand display software with only the features or functions you need. If the sensor data is for certification or environmental reporting, then a more sophisticated sensor system with a more advanced software package is a good choice. Many sensor systems can be integrated with auditing and reporting software to automate the reporting process. Use the reporting templates or reporting requirements to guide your decision on which sensor system provide the data you need.

3) What type of sensors to use?

There is a wide variety of sensor types available that appear to do the same job but many have been designed for a specific purpose. For example, soil moisture sensors measure how much water is in soil or growing media. However, there are different methods of measuring soil moisture which influence sensor cost, where they are used, and the data they provide. For soilless organic growing media, a Time Domain Reflectometry (TDR) sensor should be used instead of a capacitance sensor because TDR sensors are not affected by temperature or the physical properties of organic growing media. An added benefit is TDR sensors can also measure root zone electrical conductivity (EC), and temperature with a single sensor. Talk to the supplier to ensure the sensors you use are appropriate for the purpose.

4) What is the power and communications requirements of the sensors?

Most modern sensors are low voltage devices that can use a battery and solar power, which is perfect for portable systems. However, you must ensure the right size battery and solar panel is chosen to account for any cloudy and rainy days. Use 240-volt power if it is available, safe to use, and the sensors are stationary, as this will provide a more stable power supply for both the sensors and communications units.

The communications type will also influence the power requirements and cost. Most sensors have several communications options, e.g. hardwired ethernet cable, WiFi, 4G mobile phone system, satellite, or a nested network system. The type of communications used will depend on the location, strength of the WiFi signal, quality of internet access, or mobile phone coverage.

Using a WiFi system or nested network system is a cheaper option with little on-going costs but WiFi repeaters may need to be install. Mobile 4G and satellite systems are a good option if WiFi or internet connections are a problem, but they will require an on-going subscription to a Telco service provider, and there may be restrictions on the amount of data they will transmit.

Sensor suppliers usually offer a range of power and communication options to suit the type of sensor and location, so make sure you understand what options best suit your situation.

5) How much data do you want?

The more sensors or technology installed, the more data you will need to store, monitor, and understand. The amount of data and measurement interval will influence the on-going costs of the system. Sensors that transmit data in real-time are continually active, use more power, generate more data, and have higher ongoing costs than sensor systems that only wake-up once every 30 to 60 minutes to take a measurement and transmit the data.

If a WiFi or network sensor system is used and the data is saved to a computer onsite then data storage and communications costs are not too much of an issue. However, if a mobile 4G or satellite communication system is used, a data plan large enough to accommodate the amount of data transmitted will be needed, and if there are multiple sensor and comms units installed, multiple data plans may be needed. Also, if a third-party (cloud based) data storage and interpretation service is used then the ongoing costs will increase considerably with the amount of data collected and number of sensors to be interpreted.

Determine how much and how often the data needs to be transmitted for each sensor system before purchasing the systems. For example, if you are using soil moisture sensors to control irrigation then the sensor system will need to monitor irrigation in real-time, every 1 to 5 minutes depending on the irrigation schedule. In this case it may be better to invest in a high-quality WiFi or network system onsite to avoid ongoing communication cost. However, monitoring the pH and EC of dam water will only need to be measured a few times a day, therefore, installing a mobile 4G system may be cheaper because of the reduced data transmission requirements.

6) Which Data service or Dashboard to use?

No matter which sensor system is installed it will need some form of dashboard or software to display the data for easy viewing. Some sensor systems will come with a basic graphical display software that will help you to see daily fluctuations and trends in the data but rarely have any interpretation or prediction ability. It will be up to you to interpret the data and determine how to use that data.

Alternatively, there are a variety of service providers that will offer a more advanced cloud-based dashboard and data interpretation service separate to the installation of the sensors. These dashboards and data interpretation providers will help you to understand what the data is telling you and provide crop predictions, e.g. when the next irrigation is needed. Many will generate a variety of reports that can be used to track resource usage or be used for certification and environmental reporting, but the more automated and sophisticated the service the higher the subscription costs.

If you are considering installing any form of smart sensors or AgriTech, visit the Agtech Finder or the Agtech Toolbox websites and search for products and information, or speak to your state GIA Extension Officer or the GIA Smart Farming Officer.