Shining a light on nitrogen management: prediction modelling to detect nitrogen requirements in potato crops using the spectroradiometer

Farmers have the important task of feeding Canada and the world. But this isn`t without challenges. Agricultural producers must not only improve their farm’s productivity to fulfill the demand of rising populations, but they must also produce food sustainably to protect the environment for their future generations.

Dr. Keshav Dahal, a plant physiologist at Agriculture and Agri-Food Canada’s Fredericton Research and Development Centre in New Brunswick, is developing a prediction model that uses a light-based tool to help potato producers improve their nitrogen management practices, minimize damage to crops, and protect the environment. But what is nitrogen and why is it so important in agriculture?

Nitrogen management in agriculture

Nitrogen is an essential nutrient for plant growth and development. A delicate balance is needed to provide crops with the precise amount of nitrogen to successfully produce food. Insufficient nitrogen may reduce crop yield, while too much may lead to decreased crop quality, increased disease susceptibility, and excess nitrate leaching from the soil. Without proper management, the overuse of nitrogen in crops can contribute to poor groundwater quality, greenhouse gas emissions, and environmental and economic losses to growers. Therefore, controlling the amount, frequency, and timing of nitrogen application to crops is essential to getting the most productivity from the field, while minimizing environmental and financial impacts.

That’s why Dr. Dahal’s research is centered around developing a prediction model that will help improve current nitrogen management practices in potato field conditions. To assist him with this research, Dr. Dahal used a unique tool called the spectroradiometer, a rapid, precise, and non-destructive device that has sensors to capture and measure light reflectance patterns in crops. Although spectroradiometers have been used in the past to detect plant chemical components of various crops, Dr. Dahal’s prediction model will specifically be designed to detect and estimate nitrogen content in potato crops in field conditions using this tool to help producers monitor the application of nitrogen fertilizers throughout the growing season.

A crystal ball for improved nitrogen management practices

From 2021 to 2024, Dr. Dahal and his team of technicians at the Fredericton Research and Development Centre have been conducting field trials and studying the distinct relationship between the nitrogen found in potato plants and the light patterns the plants reflect, which can be detected by the spectroradiometer.

Between May and October of each year, Dr. Dahal applied various treatments of nitrogen fertilizer on potato fields, while using the spectroradiometer to study the nitrogen content as well as the light reflectance patterns of potato plants under each treatment.

By examining the link between the nitrogen treatments and the light reflectance patterns measured in nanometres by the spectroradiometer, Dr. Dahal is now able to develop a prediction model that could estimate the real-time nitrogen content of potato crops directly in the field, at a large scale and throughout the growing season. Dr. Dahal’s research is unique as he was able to measure over nine hundred nanometres of wavelengths to correlate the light reflectance patterns of potato plants across various nitrogen treatments in his trials, increasing the accuracy of nitrogen estimation in potato leaves.

Used alongside the spectroradiometer, this new prediction model could be utilized by the potato industry, including producers, agronomists, and researchers, to not only provide them with important information about a plant’s existing nitrogen status and requirements throughout its growth, but also to allow users to apply nitrogen fertilizers to crops when they need it most. For potato producers, the model would enable them to implement improved nitrogen management practices on their farms such as the split application method, which is the practice of applying nitrogen fertilizer at two or more intervals over the growing season to balance applications with crop demand, as opposed to a one-time application at seeding.

“Synchronizing the application of nitrogen fertilizers with the crop’s specific nitrogen requirements offers the potential to improve crop productivity and maintain soil health and our environment. It is both economically and environmentally beneficial for farmers to consider proper nitrogen management practices.”

–Dr. Keshav Dahal, plant physiologist at the Fredericton Research and Development Centre

A full spectrum of benefits

Dr. Dahal’s prediction model is set to be completed by the end of 2025 and shows great potential by increasing opportunities to measure nitrogen content of potato crops and help with monitoring the application of fertilizers, ultimately reducing the financial impact for producers and better protecting the environment.

“The prediction model developed through this study will be useful in monitoring nitrogen content in potato plants over the growing seasons. This will enable growers to make quick management decisions that are critical for preventing nutrient loss, maintaining soil health and environmental sustainability without compromising crop performance and productivity.”

–Dr. Keshav Dahal, plant physiologist at the Fredericton Research and Development Centre

Dr. Dahal will continue to develop the predictive model that will help producers incorporate spectral tools, like the spectroradiometer, for potato crops and perhaps, one day, for wheat and canola. Through Dr. Dahal’s research on improved nitrogen management practices, the future is looking bright for farmers who grow sustainable food for Canada and the world.

Key discoveries

• Dr. Keshav Dahal, Agriculture and Agri-Food Canada plant physiologist at the Fredericton Research and Development Centre in New Brunswick, is developing a prediction model that utilizes a light-based tool to help potato producers improve their nitrogen management practices, minimize damage to crops, and protect the environment.
• Dr. Dahal’s research trials studied the unique relationship between the nitrogen found in potato plants and the light patterns the plants reflect, which can be detected by the spectroradiometer, a rapid, precise, and non-destructive device that has sensors to capture and measure light reflectance patterns in crops.
• By examining the link between the nitrogen treatments and the light reflectance patterns measured in nanometres by the spectroradiometer, Dr. Dahal is now able to develop a prediction model that could estimate the real-time nitrogen content of potato crops directly in the field, at a large scale and throughout the growing season.
• Used alongside the spectroradiometer, this new prediction model could be utilized by the potato industry, including producers, agronomists, and researchers, to not only provide them with important information about a plant’s existing nitrogen status and requirements throughout its growth, but also to allow users to apply nitrogen fertilizers to crops when they need it most.
• Dr. Keshav Dahal’s prediction model is set to be completed by the end of 2025 and shows great potential by increasing opportunities to measure nitrogen content of potato crops and help with monitoring the application of fertilizers, ultimately reducing the financial impact for producers and better protecting the environment.

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Related information

• AAFC profile - Dr. Keshav Dahal’s profile
• Fredericton Research and Development Centre - Directory of scientists and professionals