Abstract
A valuable input to crop growth and yield models would be estimates of current crop condition. If multispectral reflectance indicates crop condition, then remote sensing may provide an additional tool for crop assessment. Field experiments were conducted on a typic Argiaquoll at the Purdue Agronomy Farm, West Lafayette, IN to determine the effects of nitrogen fertilization on the spectral reflectance and agronomic characteristics of winter wheat (Triticum aestivum L). The fertilization treatments consisted of 0, 60, and 120 kg N/ha, applied as urea in the spring. Spectral reflectance was measured 11 times during the 1979 growing season and 10 times during the 1980 growing season with a spectroradiometer (Exotech 20C) in the 400-2400 nm wavelength region. Agronomic data included total leaf N concentration, leaf chlorophyll concentration, stage of development, leaf area index, plant moisture, and fresh and dry phytomass. Relationships between spectral and agronomic variables were developed using data from 1979 and tested with data from 1980. N fertilization of wheat reduced visible, increased near infrared, and deceased middle infrared reflectance. These changes were related to lower levels of chlorophyll and reduced leaf area in the nonfertilized plots. Green LAI, an important descriptor of wheat canopies, could be reliably estimated with multispectral data. This study demonstrated that N-stressed wheat could be distinguished from healthy wheat spectrally and, therefore, that multispectral imagery may be useful for monitoring crop condition.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 47-61 |
| Number of pages | 15 |
| Journal | Remote Sensing of Environment |
| Volume | 19 |
| Issue number | 1 |
| DOIs | |
| State | Published - Feb 1986 |
Bibliographical note
Funding Information:*Journal Paper No. 10,151, Purdue University Agricultural Experiment Station. This study was supported by NASA Johnson Space Center, Contracts NAS9-15466 and -16528. ~Former graduate research assistant (currently research assistant, University of Alaska); senior research agronomist (currently director, Remote Sensing Laboratory, University of Minnesota); and senior research agronomist, Purdue University.