Precision Agriculture

, Volume 7, Issue 4, pp 233–248

Spectral and thermal sensing for nitrogen and water status in rainfed and irrigated wheat environments

Authors

    • USDA-ARS, U.S. Water Conservation Laboratory
  • D. Rodriguez
    • Department of Primary Industries and Fisheries
  • L. K. Christensen
    • Nordic Genebank
  • R. Belford
    • Primary Industries Research, Grains Innovation Park
  • V. O. Sadras
    • SARDI, Waite Research Precinct
  • T. R. Clarke
    • USDA-ARS, U.S. Water Conservation Laboratory
Article

DOI: 10.1007/s11119-006-9011-z

Cite this article as:
Fitzgerald, G.J., Rodriguez, D., Christensen, L.K. et al. Precision Agric (2006) 7: 233. doi:10.1007/s11119-006-9011-z

Abstract

Variable-rate technologies and site-specific crop nutrient management require real-time spatial information about the potential for response to in-season crop management interventions. Thermal and spectral properties of canopies can provide relevant information for non-destructive measurement of crop water and nitrogen stresses. In previous studies, foliage temperature was successfully estimated from canopy-scale (mixed foliage and soil) temperatures and the multispectral Canopy Chlorophyll Content Index (CCCI) was effective in measuring canopy-scale N status in rainfed wheat (Triticum aestivum L.) systems in Horsham, Victoria, Australia. In the present study, results showed that under irrigated wheat systems in Maricopa, Arizona, USA, the theoretical derivation of foliage temperature unmixing produced relationships similar to those in Horsham. Derivation of the CCCI led to an r2 relationship with chlorophyll a of 0.53 after Zadoks stage 43. This was later than the relationship (r2 = 0.68) developed for Horsham after Zadoks stage 33 but early enough to be used for potential mid-season N fertilizer recommendations. Additionally, ground-based hyperspectral data estimated plant N (g kg−1) in Horsham with an r2 = 0.86 but was confounded by water supply and N interactions. By combining canopy thermal and spectral properties, varying water and N status can potentially be identified eventually permitting targeted N applications to those parts of a field where N can be used most efficiently by the crop.

Keywords

Remote sensingThermal sensingCrop stress indexCCCIChlorophyllNitrogenWater stressWheat

Copyright information

© Springer Science+Business Media, LLC 2006