Diffuse reflectance spectroscopy to estimate soil attributes of Brazilian wetlands
Abstract
The study of soils and characterization of its attributes are continually evolving, however, for the condition of wetlands, such information is still scarce and poorly distributed. Thus, the objective of this work was to characterize spectrally the soils of a wetland area. On the study area were collected georeferenced soil samples and sent for chemical and physical analysis routine and then subjected to spectral evaluation. Were identified seven soil classes with hydromorphic characteristics in their spectral curves? The information contained in these curves then led the development of equations for soil attributes. Sand was the physical attribute of a better correlation with laboratory data and Cationic Exchange Capacity (CEC), the chemical attributes that showed better results.
Keywords
Download Options
Introduction
The soil study and its inherent agronomic characteristics consist of a number of commonly used tools and extensive domain. Among these studies, we highlight those aimed at quantifying various chemical and physical attributes. Differences in environmental conditions where soils are located are frequent and, in this sense, it is important to emphasize the low amount of existing information on lowland soils and their potential for agricultural productivity (Chicati et al., 20091). According Fageira et al. (2000)2, these soils have productive potential to supply two to three annual crops, since properly managed, especially regarding fertilization.
In this sense, the diffuse reflectance spectroradiometry techniques are presented as an alternative way to obtain accurate results (Shepherd & Walsh, 20023), to the management of soil properties, non-destructively and can be used in short studies or medium term (Udelhoven et al. 20034; Viscarra-Rossel et al., 20065). To quantify soil attributes from its spectral response, you must have good understanding of the relationships between its components and their interaction with electromagnetic radiation (Sousa Jr. et al., 20086).
In such studies, seeks to establish a specific behavior or spectral signature of soils derived, according Stoner & Baumgardner (1981)7, the inherent spectral behavior of heterogeneous combination of materials, such as particle size, soil structure, surface roughness, moisture, organic matter content, carbonate minerals content, presence or absence of quartz and iron oxides (Shepherd & Walsh, 2002; Dalmolin et al., 20058; Nanni & Demattê, 20069). Fiorio & Demattê, 200910) also point out that the best way to understand the variations of the spectral data in orbital level is to know their behavior through radiometric measurements in the laboratory. This procedure tends to reveal the characteristics closer to reality for the study object.
Thus, the objective of this study was to obtain parameters to estimate soil attributes, in this case specifically floodplains, using for both the spectral characteristics inherent to them.
Conclusion
The equations generated by the statistical model showed to be efficient in the characterization of the attributes relating to lowland soils, and the best correlations to the surface layer thereof. The sand content was the physical attribute with better accuracy rate in estimating the equations, while among chemical attributes, CEC showed better results.