Change in spatial variability structure of NDVI readings related to observation scale

E. M. Pena-Yewtukhiw, G. J. Schwab, O. Wendroth, L. W. Murdock, T. Stombaugh

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


The efficient use of real-time canopy sensors for the variable rate application of nitrogen (N) requires knowledge of the scale (resolution) of the variation in the measured property. Knowing the amount of optical data needed per unit area for efficient fertilizer application requires that we know or estimate the most efficient combination of physical sensor density (number of sensors along the applicator boom) and sensor output density (sensor readings per unit distance/area). However, reducing the density of sensor and their output would reduce the capital cost of N applicators. The objective of this study was to test the number of sensors and sampling grid size that will adequately describe field variation in canopy NDVI (normalized difference vegetative index). The NDVI data were collected in February, 2004, on wheat at the Zadoks Stage 26 growth stage. The spatial structure of NDVI was characterized by variogram analysis. Tested grid sizes ranged from 0.56 to 5.06 m2. Variograms for high density data sets were compared with variograms obtained with decreasing numbers of sampling points (greater grid size). It was possible to decrease data density while increasing grid size from 0.56 m2 to 5.06 m2 without affecting the field's NDVI spatial structure. The nugget, range and sill values were maintained across the evaluated grid sizes. We conclude that it is possible to increase the effective grid size to 5.06 m2 both by decreasing the number of sensors along the toolbar and by increasing the time interval in sensor data acquisition, implying that farmers could achieve optimal N applications using less capital intense machinery, and with less resolution constraints.

Original languageEnglish
Title of host publicationPrecision Agriculture 2005
Number of pages7
StatePublished - 2005
Event5th European Conference on Precision Agriculture, ECPA 2005 - Uppsala, Sweden
Duration: Jun 9 2005Jun 12 2005

Publication series

NamePrecision Agriculture 2005, ECPA 2005


Conference5th European Conference on Precision Agriculture, ECPA 2005


  • NDVI
  • Sensors
  • Variogram

ASJC Scopus subject areas

  • Agronomy and Crop Science


Dive into the research topics of 'Change in spatial variability structure of NDVI readings related to observation scale'. Together they form a unique fingerprint.

Cite this