The long-term objective of this study is to monitor the large scale spatial application of sewage sludge to the agricultural fields using spectral reflectance and remote sensing approaches. Application of sewage sludge to agricultural fields is an attractive practice that is gaining importance as a low cost approach to improve the soil fertility in recent years. With the 1991 ban on ocean dumping of sewage sludge and high cost involved with sludge incineration and land-filling, the application of sludge to agricultural fields has gained momentum. Sludge application can be ecologically sound only when precautions are taken to avoid over fertilization and limit the buildup of heavy metals in the soils. In recent years, most of the sewage sludge produced in North-west Ohio is being applied to agricultural fields as a means of basal fertilizer. Application of this sewage sludge is very important to monitor because it is often associated with variable nutrient and heavy metal concentrations, generation of bio-aerosols, and unpleasant odor. Several studies have documented the nutrient leaching, heavy metal buildup and pathogen problems due to excess application of sewage sludge in agriculture fields. Hence in this study we investigated the use of spectral reflectance to map the unique spectral features of the sewage sludge applied agricultural fields. The objective of this study is to analyze the unique spectral features of the agricultural fields applied with sewage sludge and to map these fields by satellite remote sensing using LANDSAT imageries. A Field Spec Pro spectroradiometer from ASD Inc. (Boulder, CO) was used to collect reflectance spectra on cloud-free, sunny days during the sewage sludge application process in agricultural fields of the identified local farmers. The fore-optics of the spectroradiometer was hold to look vertically (90„a) down, and the height of the fore-optics was adjusted so that the Field Of View (FOV) of the instrument is covered with only the reflectance from the targeted area of the field. The spectral reflectance was obtained from a total of 6 sludge applied fields and 6 control or untreated fields during the sludge application periods of 2004 and 2005. During each spectral collection a total of 10 spectra were collected at 5 different locations within the sludge applied field and the same procedure was repeated over the control or untreated fields. All the spectra that were collected within each field were averaged to overcome the individual variations and the spectral wavelengths corresponding to the 6 LANDSAT bands were averaged from the spectral data. The spectral range of these 6 LANDSAT bands are; Band 1: 450-520 nm; Band 2: 530-600 nm; Band 3: 630-690 nm; Band 4: 760-900 nm; Band 5: 1550-1750 nm; Band 7: 2080-2350 nm. From these 6 LANDSAT bands, 15 non-reciprocal spectral ratios were calculated. These spectral ratios are: R2,1; R3,1; R3,2; R4,1; R4,2; R4,3; R5,1; R5,2; R5,3; R5,4; R7,1; R7,2; R7,3; R7,4; R7,5 where R represents the ratio and the numbers represent the LANDSAT bands. For Eg: R2,1 refers to the ratio of band 2 over band 1. The spectral averages and the spectral ratios were calculated using Microsoft Excel. The best spectral ratios were selected based on the Duncan's multiple range test. The spectral results showed a consistent and systematic difference in the spectra obtained form the sludge applied fields compared to the control fields. The spectra of the sludge applied fields remained low in the entire spectral region from 350-2500 nm compared to the control fields. The sludge applied fields showed characteristic absorption bands around 600-800 nm region and 1200 nm region of the spectra. A spectral ratio index based on these uncommon spectral features can be used for mapping sludge application from the remote sensing imagery. This study suggests that remote sensing is one such an approach which contributes to the detection and identification of the environmental alterations and changes in the land use using the non-destructive and cost effective techniques. The surface application of sewage sludge soon after the winter wheat harvest in north-west Ohio is a surface phenomenon which can be retrieved by the reflectance measured by a sensor system. Because the characteristics of radiation reflected from a material is a function of its physical and chemical properties, the observation of the surface reflectance of the sewage sludge applied fields can principally carry information on the state of the field. Spectral absorption and reflectance changes obtained in the 350-2500 nm spectral range using a spectroradiometer can provide diagnostic features which can be used to identify and map the fields applied with sewage sludge further using LANDSAT imageries.