USING UAV-DERIVED PLANT HEIGHT AS AN ESTIMATOR FOR BIOMASS AND N-UPTAKE

Abstract. In Precision Agriculture applications, the knowledge of the N-uptake of crops in a spatial context is a precondition for precise N-fertilization. Therefore, non-destructive methods to determine N concentration or N-uptake of crops are of key interest. In this contribution, we will present an approach based on UAV-based crop height analysis to estimate N-uptake. The hypothesis is that biomass can be very well estimated using UAV-derived crop height. It is also known that biomass is highly correlated with N-uptake. Hence, we propose to use UAV-derived crop height as a direct estimator for N-uptake. We will present results from a winter wheat field trial comprising six varieties, three different N amounts, and five repetitions. Multitemporal models have been created from data of the growing season 2020 with a promising performance for biomass (R² = 0.91) and N-uptake (R² = 0.72). The two linear regression models have been applied to a similar independent data set from the following year, 2021. The results are promising for biomass (R² = 0.82) and N-uptake (R² = 0.75). Based on our findings, we conclude that UAV-derived crop height - as a structural crop trait - can robustly serve as an estimator for biomass and N-uptake in winter wheat.