UF/IFAS researchers deploy drones to perfect nutrient rates

CLAY COUNTY – The ability to detect crop nutrient deficiencies and promptly modify fertilizer applications to address them is invaluable to agricultural producers — especially growers operating under slim profit margins.

Identifying how much of a particular nutrient to add, however, is a balancing act. A UF/IFAS research project underway endeavors to remove the guesswork by providing growers with site-specific data.

UF/IFAS Best Management Practices Lab coordinator Lakesh Sharma leads a team of researchers using drones to develop algorithms that estimate nutrient application rates for optimal crop yields. They are within months of finalizing results related to the nitrogen needs of corn and cotton.

“In the near future, growers will be able to use sensors to detect how much nitrogen is present in plant leaves and, based on our algorithms, calculate how much additional nitrogen is needed by their crops,” said Sharma, assistant professor of soil fertility and sustainable agriculture.

Establishing optimum nitrogen rates is important because nitrogen is a mobile nutrient easily displaced by water, soil, gases and other factors.

It’s also a costly commodity.

“If farmers apply too much, it cuts into their profit margins,” Sharma said. “But they’re also mindful that if they apply less than what is needed, they could go out of business due to yield losses.” Sharma’s study is one facet of the UF/IFAS Nutrient Management Program, a suite of state-funded research projects updating decades-old nutrient application recommendations for Florida crops. The new rates are meant to deliver crop yields of the highest quality and quantity while minimizing adverse environmental effects.

Sharma is developing his algorithms using the Normalized Difference Vegetation Index (NDVI), an established predictor of plant health. NDVI values are a ratio of the red wavelengths and near-infrared wavelengths reflected by plant leaves. Values range from -1 to 1, with low, negative values indicating water or clouds, 0 indicating bare soil and high, positive values indicating lush vegetation.

“We are making growers aware of this technology and exposing them to it as much as possible, so they can understand how it works and how they can benefit from it,” Sharma said.