Effect of fermentation residue on the spectral reflectance properties of soils

Considering that the reflected electromagnetic energy from a soil sample interacts with many of its components (mineralogy, texture and chemical properties), remote sensing can be important to detect the presence of industry residues in the soil. An example of these residues is the largely used vinasse, originated from the production of ethanol by fermentation of sugarcane. Therefore, the objective of this study was to evaluate, using remote sensing the effect of this residue on the reflectance properties of two important tropical soils, a Typic Quartzipsament (TQ) and a Typic Argiudoll (TA) collected in São Paulo State (Brazil). The soil samples were treated with different doses of the residue and incubated. An Infra Red Intelligent Spectroradiometer sensor was used in laboratory. TQ presented a differentiated spectral reflectance (SR) curve in relation to TA, due to low Fe, organic matter and magnetite contents. Significant spectral differences in the reflectance intensities and absorption bands were found between both soils. The reactions of the residue with soils altered their chemical properties and increased reflectance intensity as well, according to the doses. Higher significant differences were observed in the reflectance of TQ. The proportional increase of the reflectance with doses of residue was due to the increase of calcium and potassium contents present in the product. The bands that detected residue presence in the soils were those of 760–900, 2.080–2.350, 2.350–2.500 nm for TQ, and 760–900, 1.118–1.270, 1.300–1.460, 1.550–1.750 nm for TA. Remote sensing technique as soil line was important on the detection of residue variations. The TM-Landsat data simulation presented the same behavior as in the laboratory, but less detailed. These elements contribute to the increase in reflectance not altering, however, the shape of the curves or the absorption bands. This study presents a new research trend where remote sensing can be used in agriculture as well as in environmental monitoring studies related to residues.