Stacking and Intersecting Nutrient 4Rs and Using In-Season Canopy Health and Petiole Nitrate Analysis on Russet Burbank Potatoes

S. Stapley, B. Hopkins
Brigham Young University
Introduction
4 Rs of Nutrient Management: 
https://nutrientstewardship.org/4rs/
  • Have: significant Best Management Practice (BMP) data for each of the individual 4 Rs
  • Need: more data evaluating the combined (stacked) effects
  • Objective: learn how interactions of 4 Rs impact crop yield and quality
 
Materials and Methods
  • Russet Burbank potato (Solanum tuberosum L.)
  • Field study near Grace, ID
  • Randomized Complete Block Design with 6 replications of 9 treatments (see table below)
  • Measurements include:
    • NDVI
    • Petiole NO₃-N
    • Tuber quality (not yet analyzed)
    • Tuber yield (not yet analyzed)
    • Whole plant total N (not yet analyzed)
 
Results and Conclusion
  • Field was responsive to N
    • ​Negative control - significant reductions in NDVI and petiole NO₃-N at every sampling date
  • Petiole NO₃-N:
    • All treatments identical to Grower's Standard Practice (except positive control)
  • NDVI:
    • No differences for fertilized treatments until last sampling date
    • All treatments with PCU performed as well as Grower's Standard Practice
    • Other urea treatments significantly lower
    • Rate treatment (urea applied at reduced rate) performed worst
Fig. 1. Potato petiole nitrate-nitrogen. Asterisks indicate values significantly different than Grower Standard Practice (GSP).
 
Fig. 2. Potato Normalized Difference Vegetative Index (NDVI). Values or groups of values close to one another sharing the same letter are not statistically different from one another. (P = 0.05)
 
The in-season data suggest PCU is a reliable N source for potatoes, even at reduced rates. Analysis of other measurements will provide more information on the efficacy of 4R implementation.