Elevating Agricultural Sustainability in Europe: Satellite-based Fertilizer Recommendations for Decision Makers

Field-specific Fertilizer rate recommendations and farm-specific Fertilizer demand estimation have been a decade-old problem. Soil testing and plant tissue testing are still regarded as the most dependable solutions. However, this is a time-consuming and labor-intensive process. The closest alternative is the field sensors, which use the Near Infrared (NIR) light reflectance of plant leaves to estimate Fertilizer application rates. This technology has made life more straightforward but still requires field scouting and a significant initial investment. Historically, scientific groups have developed several crop models that provide an efficient solution for Fertilizer advice. However, crop models are complicated and require high-quality soil and meteorological data, which we do not have at the field scale. On the contrary, the satellite image-based Fertilizer recommendation method eliminates the need for field scouting and is useful for Variable Rate applications; however, it fails to address the rate recommendation challenges.

Spacenus GmbH is a satellite remote-sensing company working on this problem since 2017. Spacenus developed a solution to detect plant nutrient status in the lab, which was then transferred to the field condition, allowing us to estimate plant nutrient demand from satellite imagery and provide plant need-based, site-specific Fertilizer rate recommendations. The system has been tested with farmers throughout Europe from 2018 to 2021. It has proven beneficial to farmers regarding Fertilizer input cost savings and complying with various European Fertilizer regulations.

Since 2021, Fertilizer prices have risen dramatically, triggering some interest among Fertilizer manufacturers and retailers in predicting location-specific Fertilizer demand and enabling data-driven digital sales. This requires Fertilizer rate recommendations at the regional level. Using historical satellite images, we have begun to analyze each field in Europe to identify crop and field-specific nutrient uptake during the previous five years. Those crop-specific nutrient uptake estimates were aggregated into district levels, which were then revised depending on district-specific yield, soil, and weather conditions, resulting in district-specific, crop-wise Fertilizer rate recommendations for the entire Europe.

Regional Fertilizer rate recommendations are a straightforward tool but extremely helpful in improving fertilizer use efficiency across geographies and efficiently enforcing Fertilizer regulations at the local level. The blanket rate recommendations at the national or state levels are ineffective because they penalize high-yielding areas while allowing excess Fertilizers to leak into the environment in low-yielding areas. We took it a step further for Germany. We wanted to determine how much value we could contribute by producing post-code-based Fertilizer rate recommendations. The end result was fantastic. It provides additional details, which might be useful in advising and controlling Fertilizer use even at the postcode level. This will eventually assist farmers to grow food more sustainably while improving the environment's quality over time.

Above, we propose Fertilizer rates for a wheat crop in Europe. Because of the post-code-based recommendation in Germany, the spatial rate recommendation resolution is high, but in the rest of Europe, the recommendation is currently at the district level. We compared our recommendations to crop-specific Fertilizers use by the nation, and it is pretty aligned. The wheat yield in Western Europe is higher, so recommendations are relatively higher. The yield gap in Eastern Europe is large, so the recommendation remains relatively low. We intend to expand it up to the postcode level for all of Europe and make similar maps available internationally.

This is the first map of its kind that includes regional-specific Fertilizer rate recommendations, making it an excellent tool for policymakers, environmental specialists, Fertilizer manufacturers, retailers, food companies, water supply companies, and many more. We envision a future in which such a tool serves as a standard that helps streamline various activities such as creating policies, ensuring environment-aware field activities, fighting climate change, and delivering sustainable food to all of our plates.