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Mapping Christmas tree nutrition requirements using unmanned aerial vehicles and multispectral sensors

Two balsam fir fields were selected for this study: one in Belmont, NS (45.37N, 63.24W) and one in Bible Hill, NS (45.37N, 63.24W). All trees were tagged for identification and then 25 trees were randomly sampled from each field. Soil samples were taken along the dripline of each tree and two small branches were cut to obtain needle tissue samples. Simultaneously, an unmanned aerial vehicle equipped with a multi-spectral camera was flown over each site to collect imaging data. This was conducted once in autumn of 2021 and then again in spring 2022 with an additional 25 data points. The two fields have several significant differences in soil and tissue nutrition. Perhaps most relevant is the fact that nitrogen concentrations are significantly higher in soils and tissues at the Belmont site. Higher nitrogen in Belmont is not unexpected because Belmont is maintained as a commercial lot while the orchard in Bible Hill is not. The range of nitrogen concentrations is relatively large, which will be helpful in creating comprehensive models. Soil nitrogen ranges from 1.23 – 24.54 ppm while needle tissue nitrogen ranges from 0.83 – 2.32%. Normalized difference vegetation indices (NDVI) were created from multispectral camera photos and compared to soil and tissue nutrition. There were generally weak relationships between soil nutrition and NDVI, but there were stronger relationships between tissue N, P, and K and NDVI. The tissue nutrition relationships were even stronger for trees more than 5 years old. In particular, NDVI explained up to 60% of the variability in tissue N making it a decent predictive tool in determining N concentration in balsam fir.

  • Project ID21-02-DU
  • CategoriesSoil and Fertility
  • Growing Region(s)Northeast
  • Tree SpeciesFir
  • Investigator(s)MacDonald
  • Institution(s)Dalhousie University
  • Research Year2021
  • Publication Year2023
  • ReportDownload 📁