The cost of soybean production is increasing. Nutrient inputs are at historically high costs at a time where there is increased variability in growing season conditions. Crops can experience multiple kinds of stresses and better information is needed on strategies that allow the crop to perform as well as possible while using a minimum of inputs. In North Carolina three of the most substantial production costs are seed, nutrient inputs, and water management infrastructure. This project further develops relationships between water stresses and nutrient uptake so that the response to stress conditions will protect the variety’s yield potential, optimize nutrients, and suggest water management approaches – addressing all the major cost centers. The larger outcome of this research and extension effort is in-season response to water challenges such that nutrient input may be reduced, applications timed to environmental stress and profitability improved.
The ability to utilize UAV data to assess plant water and nutrient stress in-season as it occurs and ultimately use the data to prescribe an appropriate course of action is necessary to protect soybean crop profits. This process will provide a framework to quickly assess areas in the field and allow for corrective measures to protect the crop from climatic conditions that ultimate would cause severe yield reductions.

The goal of this research and extension project is to optimize nutrient management based on UAV-measured water stress experienced early in the growing season. The specific objectives are to:
1. Subject select soybean varieties to water stresses and quantify stress using UAV imagery.
2. Evaluate nutrient uptake in water stressed varieties over multiple growth stages.
3. Correlate nutrient uptake to a reflectance-measured water stress indicator and final crop yield.
4. Develop and provide in-season nutrient management recommendations based on water impacts.

The expected end product is to provide data necessary to timely evaluate the newest soybean varieties’ nutrient uptake to soil water stress. This will promote better fertility management of varieties given a producers ability to manage water stress. The development of a relative crop water stress index through timely produced UAV imagery, with the ultimate product being higher returns to the grower by improving his ability to quickly quantify in season fertility stress caused by climatic induced water stress.
This project will provide a better understanding of in season fertility needs given soil water stress observed at the farm level. This will enhance fertilizer use and lower fertilize expense by tailoring application based on climatic conditions and nutrient needs.