Peterson Ricardo Fiorio

Orbital and laboratory spectral data to optimize soil analysis.

Traditional soil analyses are time-consuming with high cost and environmental risks, thus the use of new technologies such as remote sensing have to be estimulated. The purpose of this work was to quantify soil attributes by laboratory and orbital sensors as a non-destructive and a non-pollutant method. The study area was in the region of Barra Bonita, state of Sao Paulo, Brazil, in a 473 ha bare soil area. A sampling grid was established (100 × 100 m), with a total of 474 locations and a total of 948 soil samples. Each location was georeferenced and soil samples were collected for analysis. Reflectance data for each soil sample was measured with a laboratory sensor (450 to 2,500 nm). For the same locations, reflectance data was obtained from a TM-Landsat-5 image. Multiple linear regression equations were developed for 50% of the samples. Two models were developed: one for spectroradiometric laboratory data and the second for TM-Landsat-5 orbital data. The remaining 50% of the samples were used to validate the models. The test compared the attribute content quantified by the spectral models and that determined in the laboratory (conventional methods). The highest coefficients of determination for the laboratory data were for clay content (R2 = 0.86) and sand (R2 = 0.82) and for the orbital data (R2 = 0.61 and 0.63, respectively). By using the present methodology, it was possible to estimate CEC (R2 = 0.64) by the laboratory sensor. Laboratory and orbital sensors can optimize time, costs and environment pollutants when associated with traditional soil analysis.

Cronologia e impacto ambiental do uso da terra na Microbacia Hidrográfica do Ceveiro, em Piracicaba, SP

Este trabalho objetivou avaliar a cronologia e o impacto ambiental do uso da terra na Microbacia Hidrografica do Ceveiro (MHC), nos anos de 1962, 1965, 1978 e 1995. Utilizou-se a fotointerpretacao e geoprocessamento, o que permitiu uma rapida e eficiente integracao entre os dados levantados. Os solos da area sao basicamente Litossolos e Podzolicos Vermelho-Amarelos. A cultura anual, que em 1965 chegou a ocupar 42% da area da microbacia, em 1995 ocupava 0,15%. Nesse mesmo periodo, o plantio da cana-de-acucar passou de 16% para 66%, sendo esta cultura a principal causa da diminuicao das culturas anuais na microbacia. O maior aumento do plantio da cana-de-acucar ocorreu de 1978 a 1995, caracterizando, assim, a influencia dos incentivos governamentais para o seu cultivo. As pastagens e os reflorestamentos tambem contribuiram para a expansao do plantio da cana-de-acucar, com uma diminuicao em area de 48% das pastagens e 42% do reflorestamento. As areas de mata nativa e urbana apresentaram um aumento de 1962 a 1995. O impacto ambiental na MHC tem como indicador a represa da Vila de Artemis, que, de 1978 a 1995, diminuiu sua area em 50%, em decorrencia do assoreamento.

Diferenciação espectral de solos utilizando dados obtidos em laboratório e por sensor orbital

A huge amount of soil samples would be necessary to determine with precision the limits of soil units. Techniques that would help on soil surveys such as the remote sensing ones have been proved to be of great value. The objective of this work was to evaluate the possibility of differentiating soils using spectral data from laboratory and satellite sensors. A study area with soils originated from two different parent materials, sandstone with loamy cement and basalt, was selected. A grid (100 m x 100 m) was used, totalizing 473 sampling points in the depths 0-20 cm (superficial, A) and 80-100 cm (subsuperficial, B). A soil map of the area with 28 mapping units was generated. The laboratory spectra (450 to 2500 nm) were obtained with an IRIS spectroradiometer. The orbital reflectance was obtained by image processing and overlaying of the TM-Landsat-5 bands in the sampling points. Discriminant equations were generated by statistical treatment with the SAS software. From the seventy initial variables from laboratory data, fifty six were selected to generate the models of the equations; for orbital data, six of the seven TM bands were selected. The equations were tested and the confusion matrix were obtained. Discriminant equations from laboratory data presented 81% success and the equations with orbital data 40%, however, for the satellite data it was verified a good efficiency for separating soils from different parent materials.

In situ separation of soil types along transects employing Vis-NIR sensors: a new view of soil evaluation

Soil components, such as organic matter, the levels and form of iron oxides, moisture and texture, influence the interaction of the soil with electromagnetic energy, so that knowledge of the energy reflected by different classes of soil is therefore of help in their discrimination. The aim of this study was to evaluate the possibility of differentiating classes of soils along two transects, by means of the field spectral behaviour of different classes, using both visual and multivariate statistical analysis. Equidistant points were marked along the transects, 100 m apart, where geo-referenced soil samples were collected from the surface layer at a depth of 0 to 0.20 m. In the area under study, ten classes of soil were described by means of laboratory analysis of surface samples and a morphological description of the profiles, with each soil being classified according to the Brazilian System of Soil Classification. For separating soil units and establishing their boundaries in the landscape three methods were used: a) traditional, evaluating the correlation between soil and landscape; b) qualitative assessment of the spectral curves; c) multivariate analysis for discrimination of the classes of soil. Comparison of these methods made possible the use of spectroradiometry in differentiating the classes of soil, with the statistical method separating a larger number of classes. It was possible to delimit the boundaries of the soil units in the area under study, as well as differences in texture, colour, total iron and organic matter between units, by varying the spectral responses of the soil samples being tested.

Potencialidade do uso da terra na microbacia hidrográfica do córrego do ceveiro na região de Piracicaba

The objective of this work was to evaluate the agricultural potential of the Ceveiro watershed Piracicaba, SP, Brazil, which contains 1990 ha considering available environmental conditions. Medium and clayey textured Ultisols and Entisols predominate. Land use was determined by remote sensing, the limits of the were digitalized and crossed with soils and shape data, using the Environmental Analysis System for Agricultural Planning. These results were then compared with the current land usage patterns that occurred in 1995, to determine if differences existed between current and prescribed land use. In 1995, 48% of the area was being used below its potential use, 27% used appropriately, and 23% used with excessive intensity. The main difference in land use between the appropriately used and excessively used areas was due to sugarcane production.

Digital soil mapping using reference area and artificial neural networks

Digital soil mapping is an alternative for the recognition of soil classes in areas where pedological surveys are not available. The main aim of this study was to obtain a digital soil map using artificial neural networks (ANN) and environmental variables that express soil-landscape relationships. This study was carried out in an area of 11,072 ha located in the Barra Bonita municipality, state of Sao Paulo, Brazil. A soil survey was obtained from a reference area of approximately 500 ha located in the center of the area studied. With the mapping units identified together with the environmental variables elevation, slope, slope plan, slope profile, convergence index, geology and geomorphic surfaces, a supervised classification by ANN was implemented. The neural network simulator used was the Java NNS with the learning algorithm back propagation. Reference points were collected for evaluating the performance of the digital map produced. The occurrence of soils in the landscape obtained in the reference area was observed in the following digital classification: medium-textured soils at the highest positions of the landscape, originating from sandstone, and clayey loam soils in the end thirds of the hillsides due to the greater presence of basalt. The variables elevation and slope were the most important factors for discriminating soil class through the ANN. An accuracy level of 82% between the reference points and the digital classification was observed. The methodology proposed allowed for a preliminary soil classification of an area not previously mapped using mapping units obtained in a reference area.

Espectroscopia VIS-NIR-SWIR na avaliação de solos ao longo de uma topossequência em Piracicaba (SP)

Objetivou-se neste trabalho caracterizar diferentes solos por espectrorradiometria de reflectância ao longo de uma topossequencia na regiao de Piracicaba, SP. Amostras de solo foram coletadas e analisadas em campo, em laboratorio de analises quimicas e por sensores Vis-NIR (400-2500 nm). Alteracoes nos solos da topossequencia foram identificaveis nas informacoes espectrais. Constituintes dos solos, tais como, materia orgânica, mineralogia, formas de oxidos de ferro e granulometria foram determinantes nas variacoes das feicoes de absorcao e intensidades de reflectância. Cada perfil mostrou caracteristicas espectrais diferenciadoras entre horizontes, relacionadas a intensidade, feicoes de absorcao e morfologia da curva. A avaliacao morfologica nao pode ser avaliada pelo sensor, sendo uma de suas limitacoes. Existe relacao entre grau de intemperismo (indices ki, relacao silte/argila e mineralogia) e dados espectrais. Isso foi observado nos solos originados de basalto, onde houve aumento do ferro extraido pelo ditionito (cristalino e amorfo) na sequencia Nitossolo Vermelho Latossolico (NVL) em direcao ao Cambissolo (C) e, aumento do ferro amorfo nesta mesma sequencia. Na avaliacao da topossequencia completa observou-se a sequencia de absorcao centrada em 500 e 850 nm decrescente do Nitossolo Vermelho Latossolico em direcao ao Chernossolo, ou seja, na sequencia de decrescimo dos teores de ferro cristalino (hematita e goethita) e aumento de ferro amorfo, corroborado pelo aumento dos valores do indice ki. Houve relacao entre os dados espectrais, o indice ki e a posicao do solo na paisagem. Esses resultados mostram que a espectrorradiometria e uma ferramenta promissora para auxiliar o levantamento de solos. Entretanto, ha necessidade do suporte a implantacao de bibliotecas de dados espectrais de solos com acesso irrestrito aos usuarios.