Canopy Light Reflectance and Field Greenness to Assess Nitrogen Fertilization and Yield of Maize

Abstract

Assessment of crop N requirements is necessary to develop production systems with optimal N input. A field experiment with six maize (Zea mays L.) hybrids grown at three N fertilizer rates (0, 100, and 200 kg N ha−1) was conducted on a well‐drained sandy loam of the Grenville series (coarse‐loamy, mixed, mesic Typic Eutrochrepts) on the Central Experimental Farm at Ottawa, ON, in Canada (45°23' N, 75°43' W) for 3 yr (from 1991 to 1993) to evaluate whether canopy reflectance and greenness can measure changes in maize yield response to N fertility. Canopy reflectance, leaf area and greenness were measured on 11 dates from 4 wk before to 4 wk after anthesis. Grain yield at harvest was also measured. Direct radiometer readings at the 600‐ and 800‐nm wavelengths or a derived normalized difference vegetation index [NDVI = (800 nm − 600 nm)/(800 nm + 600 nm)] best differentiated N and hybrid treatments at most sampling dates. Canopy light reflectance was strongly correlated with field greenness at almost all growth stages (field greenness being a product of plant leaf area and leaf greenness measured with a chlorophyll meter, in this case a SPAD‐502). Both canopy light reflectance and field greenness measured preanthesis were correlated with yield at harvest. Light reflectance measured after anthesis differentiated hybrid differences in leaf senescence. Our data suggest that light reflectance measurements prior to anthesis may predict grain yield response and provide in‐season indications of N deficiency.

Correlation of Spatial Variability of Soil Macronutrients with Crop Performance by Using Satellite and Remote Sensing Indices for Site Specific Agriculture: Chakwal Region

“…It was found that K, P, NO 3 and CaCO 3 were having significant positive correlation with NDVI values. Similar results has been described by Ma et al [15] higher the nitrogen contents increase the chlorophyll content and leading to increased NDVI values. Whereas SO 4 was having non-significant positive correlation.…”

“…Verhulst et al [14] demonstrated that the spatial variability of soil properties influence the crop performance and is correlated with the NDVI values by affecting the spectral characteristics of vegetation. Ma et al [15] showed that higher the nitrogen contents increase the chlorophyll content and leading to increased NDVI values.…”

Field Measurements of Canopy Spectra for Biomass Assessment of Small-Grain Cereals

“…4). Given that the amount of green area of a canopy determines the absorption of photosynthetic active radiation by photosynthetic organs, spectral reflectance measurements can provide an instantaneous quantitative assessment of www.intechopen.com the crop's ability to intercept radiation and photosynthesize (Ma et al, 1996). Therefore, the absorption by the crop canopy of very specific wavelengths of electromagnetic radiation is associated with certain morphological and physiological crop attributes related to the development of the total photosynthetic area of the canopy.…”

Using Multi-Spectral Imagery To Evaluate Corn Grown Under Nitrogen and Drought Stressed Conditions

“…[2] The NDVI is correlated with a number of different vegetation parameters such as leaf area, biomass, and percent cover. [3,4] Using hand-held or vehicle mounted hyper-spectral systems to measure reflectance, researchers have collected reflectance data corresponding to similar wavebands available in satellite-sensed data. Kleman and Fagerlund [5] investigated wavebands that are present on the Landsat multi-spectral scanner (MSS) using a radiometer measuring 400 to 2300 nm.…”