How to use remote sensing for crops to its fullest potential

Images from drones and satellites can be part of a much bigger picture

The amount of damage caused by cutworm feeding on canola seed-treated with an insecticide was measured. Manned aircraft were used to collect images on 90 acres. Field and data analysis was performed to develop relative density, and per cent cover maps were created to provide an objective estimate of cutworm damage.

Remote sensing tools can produce a lot of valuable information about what’s happening on farmland and within your crops, but the full potential has yet to be properly harnessed, says a north-central Alberta agronomist after studying the technology for a couple years.

Satellite imagery, aerial photography and images captured by unmanned drones are all forms of remote sensing, says Kristina Polziehn, owner of Axiom Agronomy in Sturgeon County, north of Edmonton. “Those images, that data, is an important tool, but it often represents only part of the picture needed to make management decisions,” she says.

If the information or analysis of those images could be more routinely overlaid with other information such as soil analysis, soil moisture, environmental/weather information, nutrient rates, pest management practices and yield data, for example, the combination can provide farmers with a much better idea of not only what’s happening but why it is happening in the field and what measures to take.

Kristina Polziehn. photo: Supplied

“We are starting to see some companies now provide these layering and analysis services, but Canada seems to be lagging behind what is happening in other parts of the world,” says Polziehn.

Remote sensing imagery can provide mapping and useful information on water management, nutrient management and soil characteristics, pest management including weeds, disease and insect pests, crop yield monitoring and even evaluation of different crop varieties.

Layering the information, and then hiring outside expertise to analyze and interpret the data “so it can be actionable and useable” also means additional costs, she says. “Farmers need to ask themselves what they want, what they are trying to achieve and is there value in the whole process,” she says.

Polziehn’s observations of the value of remote sensing technology was the theme of a study she undertook as the recipient of the Canadian Nuffield Agricultural Scholarship program. Awarded in 2017, the scholarship involved travel to different countries looking at how farmers used remote sensing in crop production.

Satamap imagery from Australia uses a subscription-based pricing approach to imagery for agronomists and growers interested in viewing imagery of fields. They source imagery from several satellites including Landsat 8, Sentinel 2, Sentinel 3, MODIS and Landsat. The red circle is an area of CWRS wheat that has dried down, but you can see areas that are not as advanced in dry-down. This type of simple imagery can be useful for monitoring areas of crop develop- ment. This client in the Peace River area has a number of wheat fields in the region. You can see the proportion of acres and where they are not as advanced in dry-down. ( photo: Courtesy Kristina Polziehn

She was part of a group of eight Nuffield scholars who spent six weeks traveling to Brazil, Mexico, the United States, Ireland, France and New Zealand. Later, she spent another six weeks of individual travel visiting the United States, the United Kingdom, Australia and Canada. At all stops she conducted interviews with researchers, agronomists, farmers and agri-business managers. The full report of her findings, completed in late 2019, can be found on the Nuffield Canada website at

With farm clients located from north of Edmonton up into the Peace River Region, Polziehn says she works with producers with a wide range of farm sizes and interests.

“I use remote sensing technology depending on the client’s or my own needs,” she says. “I have one client who is really interested in seeing how remote sensing technology can benefit his operation and management decisions.

“Some of the farms I work with are 20,000 to 30,000 acres in size and I may need to look at 8,000 acres of canola,” she says. “That’s a lot of ground to cover, so I can use aerial photography from a manned aircraft, or imagery from a UAV (unmanned aerial vehicle) or drone to look at these fields of canola.”

Those images can provide Polziehn useful information on the evenness of crop maturity, for example, and help identify any areas that appear to be less productive and may require further on-ground investigation.

While that is very specific and timely information, she also sees how useful it would be if other field and environmental data could also be applied to help in developing precision agriculture prescriptions for variable-rate treatments.

“The benefits and applications of remote sensing in precision agriculture are yet to be fully realized in Canada,” says Polziehn in her report. “With the vast array of imagery products available, problems with data quality, and inconsistency in data processing times and delivery [are among factors that] have impeded the uptake of imagery products.”

Most of the applications for remote sensing have also typically been utilized within research communities. At the field level, growers and agronomists are looking for imagery that is utilized as part of a decision support tool or model rather than some of the current commercial uses of imagery, which are solely visual tools, she adds.

“These digital support tools need to be simple and easily adapted to farms. Farmers and agronomists want real solutions to real problems, not solving problems created by technology. The tools need to be economical, as many farms are operating on low margins, low commodity prices and generally one crop per year.

“The usefulness of remote sensing will continue to develop as we continue to use tools to learn more about crop performance variability during the growing season and understand what drives variability on the farm,” says Polziehn. “The greatest benefits from remote sensing will continue to come as we combine imagery data with maps of yield, soil characteristics and fertility to develop sustainable and integrated precision agriculture.”

Polziehn also included five recommendations in her report, all geared to improving use and value of remote sensing in precision farming practices.

She recommends that Canada collaborate more with private and public agencies in other countries to learn how they are using remote sensing tools. She also sees a need for more precision agriculture workshops to show farmers and agronomists how to use data more effectively. Polziehn sees a need for more farm-relevant research into precision agriculture technologies, along with a need to communicate the results of precision agriculture research to farmers. And she also sees a need to include more precision agriculture technology in ag college and university course material.

About the author

Field Editor

Lee Hart

Lee Hart is editor of Cattleman’s Corner based in Calgary.



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