Navegando por Autor "Rocha, Genelício Crusoé"

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Intervalo hídrico ótimo e densidade crítica de um Latossolo Amarelo coeso sob diferentes usos no ecossistema Tabuleiro Costeiro
(Revista Ceres, 2016-09-14) Dias, Camila Brasil; Rocha, Genelício Crusoé; Assis, Igor Rodrigues de; Fernandes, Raphael Bragança Alves
Os impactos do uso e do manejo na qualidade física do solo têm sido quantificados, utilizando-se o intervalo hídrico ótimo e a densidade crítica do solo. O objetivo deste trabalho foi determinar o intervalo hídrico ótimo (IHO) e a densidade crítica de um Latossolo Amarelo coeso, dos Tabuleiros Costeiros do Recôncavo da Bahia, submetido a diferentes usos e manejo do solo. Foram selecionadas três áreas, sobre solo coeso típico, submetidas aos seguintes usos e manejos: mata nativa (Mata Atlântica); pastagem de Brachiaria decumbens Stapf, em estado de degradação, e cana-de-açúcar, com subsolagem no sulco de plantio. Foram retiradas em cada área 40 amostras com estrutura indeformada, na porção central de cada horizonte (A e AB). Foram determinados nessas amostras, após serem submetidas a dez valores de tensão e pressão, a umidade, a resistência à penetração e a densidade do solo. Na área cultivada com cana, a coleta das amostras foi feita nas linhas de plantio, onde foi realizada a subsolagem. O intervalo hídrico ótimo do horizonte A, da mata, e do Ap, da cana-de-açúcar foram semelhantes e, ambos, maiores que na pastagem. Já no horizonte AB, o IHO da cana-de-açúcar foi maior que o da mata e, o desta, maior que o da pastagem. Os horizontes A e Ap apresentaram valores de densidade crítica maiores que os de AB para todos os usos avaliados. O uso que apresentou maior frequência de valores de densidade do solo acima da densidade crítica foi a pastagem.
Multinomial logistic regression and random forest classifiers in digital mapping of soil classes in Western Haiti
(Revista Brasileira de Ciência do Solo, 2018-07-02) Jeune, Wesly; Francelino, Márcio Rocha; Souza, Eliana de; Fernandes Filho, Elpídio Inácio; Rocha, Genelício Crusoé
Digital soil mapping (DSM) has been increasingly used to provide quick and accurate spatial information to support decision-makers in agricultural and environmental planning programs. In this study, we used a DSM approach to map soils in western Haiti and compare the performance of the Multinomial Logistic Regression (MLR) with Random Forest (RF) to classify the soils. The study area of 4,300 km2 is mostly composed of diverse limestone rocks, alluvial deposits, and, to a lesser extent, basalt. A soil survey was conducted whereby soils were described and classified at 258 sites. Soil samples were collected and subjected to physical and chemical analyses. Recursive Feature Elimination (RFE) was used to select the most important covariates from auxiliary data, such as climate, lithology, and morphometric properties to describe the soil-landscape relationship. Mapping performance was assessed by the Kappa index and overall accuracy derived from a confusion matrix generated using a 5-fold cross validation process. In addition, an external mapping validation was carried out using an independent soil dataset. Accordingly, the soil dataset was split into 80 % and 20 % for training and validation of the models, respectively. No significant statistical difference (Z = 0.56< |1.96|) was found between maps generated with both classifiers (Kappa index 0.45 for MLR and 0.42 for RF). Based on the Kappa values, the classification performance can be characterized as moderate for both algorithms. Surprisingly, the RF classifier outperformed MLR in the validation process (Kappa values of 0.55 and 0.33, respectively). These results suggest a higher generalization ability of RF. However, no significant statistical difference (Z = 1.83< |1.96|) was observed. The soil map derived from RF indicated the occurrence of Leptosols (48.5 %), Gleysols (19.6 %), Chernozems (8 %), and Fluvisols (6.6 %) in most of the study area. The DSM approaches proved suitable for mapping soils in western Haiti and could be used in other parts of the country, thereby closing information gaps with regard to Haitian soils.
Physical quality of bauxite tailing after a decade of environmental recovery
(Revista Ciência Agronômica, 2018-04) Dias, Luiz Eduardo; Guimarães, Lorena Abdalla de Oliveira Prata; Rocha, Genelício Crusoé; Assis, Igor Rodrigues de; Fernandes, Raphael Bragança Alves
Tailings from bauxite washing produced in Porto Trombetas, Pará state, a Brazilian Amazon region, have chemical and physical characteristics limiting the development of plants, which hinders to revegetate the tanks where they are deposited. This study was carried out under field conditions, and aimed to assess the physical quality of these tailings after a decade of recovery practices. Three treatments were assessed: no application of inputs and planting of seedlings (T1) and two levels of fertilization, one with lower (T2) and other with higher (T3) doses of limestone and fertilizers associated with planting tree seedlings. After ten years of experimentation, penetration resistance (PR) and substrate moisture up to 60 cm depth were assessed and the least limiting water range (LLWR), water retention curve (WRC), and pore size distribution were determined and calculated. After a decade of environmental recovery, differences in physical characteristics were observed in the tailings due to different revegetation modes. Moisture in the substrate profile, LLWR, WRC, and pore size distribution were sensitive indicators to variations in substrate physical quality. Liming, fertilization, and planting of seedlings are necessary for revegetation and improvement of the physical quality of tailings. Treatment T3 was the best intervention identified so far for tank revegetation. The absence of fertilization and planting precludes revegetation even with sources of propagules nearby.