Search

Made available in DSpace on 2022-04-29T08:32:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-04-01 Changes in primary cover for agricultural crops in Amazonas region influence the phenomenon of spatial variability in soil properties. This phenomenon is still studied assuming that the spatial data is isotropic, but does not consider the anisotropic pattern of soil properties. Thus, the aim of this work was to characterize, identify and correct isotropic patterns of magnetic susceptibility (MS) measurements using anisotropic models that actually represent the spatial aspects of the data. Three cultivation areas and one under native forest, classified as Haplic Alisol, were georeferenced and sampled by a mesh system covering 192 samples per area. Texture, X-ray diffraction and frequency-dependent (χfd) and mass-specific (χlf and χhf) magnetic susceptibility analyzes were performed. Then, classical and geostatistical analyzes were applied to the data, assuming isotropy and anisotropy. All χ frequencies were shown to be spatially dependent, satisfying the isotropy hypothesis. Thereby, the application of anisotropic analysis was able to confirm the presence of all types of anisotropy in Alisols. Anisotropic correction provided an improvement in models that fit the directional trends within the areas, and provided a reduction in the nugget effect and an increase in the correlation ranges. Thus, the generated kriging maps improved the patches of zonal trends of greater or lesser χ that stand out at the level of sub-regions. These zones should, therefore, be used as indicators of variability, paying special attention during their management, especially in research related to the delimitation of specific management zones. Amazon Environment and Soil Research Group (GPSAA) Federal University of Amazonas (UFAM), Amazonas Amazon Environment and Soil Research Group (GPSAA) Center of Agricultural Sciences Federal University of Paraíba (CCA/UFPB), Paraíba Department of Agronomy Federal University of Roraima (UFRR), Roraima Soil Characterization for Specific Management Research Group (CSME) Faculty of Agrarian and Veterinary Sciences Paulista State University (FCAV/UNESP), São Paulo Department of Soils and Rural Engineering Agricultural Sciences Center Federal University of Paraíba (DSER/CCA/UFPB), Paraíba Federal Institute of Rondônia (IFRO), Rondônia Soil Characterization for Specific Management Research Group (CSME) Faculty of Agrarian and Veterinary Sciences Paulista State University (FCAV/UNESP), São Paulo

Submitted by Simone da Silva Gomes (simone.sgomes@hotmail.com.br) on 2020-08-07T19:01:36Z No. of bitstreams: 1 Simone da Silva Gomes - Tese de Doutorado.pdf: 1549380 bytes, checksum: af10786fcbb70b52c90c22a1cdb16121 (MD5) Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2020-08-12T01:07:59Z (GMT) No. of bitstreams: 1 gomes_ss_dr_jabo.pdf: 1549380 bytes, checksum: af10786fcbb70b52c90c22a1cdb16121 (MD5) Made available in DSpace on 2020-08-12T01:07:59Z (GMT). No. of bitstreams: 1 gomes_ss_dr_jabo.pdf: 1549380 bytes, checksum: af10786fcbb70b52c90c22a1cdb16121 (MD5) Previous issue date: 2020-03-12 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) A acidez do solo é um fator limitante para a produção agrícola. A calagem vem como alternativa viável para elevar os teores de pH, Ca, Mg e a saturação por bases do solo. Para que as recomendações de correção se tornem eficientes é necessário conhecer os atributos do solo e relacioná-los com a variabilidade espacial da área. O objetivo deste trabalho foi estimar a necessidade de calagem do solo pela assinatura magnética e determinar áreas de manejo específico. Foram coletadas 100 amostras de solos em uma área de 180 hectares, em Alpinópolis - MG. As amostras foram submetidas a análise granulométrica, química, mineralógica e de suscetibilidade magnética do solo (SM). A quantificação dos minerais magnéticos do solo, magnetita (Mt) e maghemita (Mh) foi obtida por SM antes e após o tratamento com ditionito- citrato-bicarbonato de sódio. Os resultados foram submetidos a análise descritiva, geoestatística e análise de árvore de regressão. Com base no banco de dados disponível, a assinatura magnética possibilita estimar com precisão a necessidade de calagem utilizando árvore de regressão. O padrão espacial da SM solo possibilita reconhecer áreas com diferentes potenciais de necessidade de calagem. Isto consolida a análise como uma ferramenta indireta e promissora na definição de áreas de manejo específico e no planejamento táticos e operacionais das atividades agrícolas que buscam incrementos na produtividade das culturas. Foi possível elaborar um protocolo alternativo de necessidade de calagem, utilizando os valores de suscetibilidade magnética e os teores de argila do solo. A SM do solo permite diferenciar a origem dos sinais magnéticos em lito-pedogenéticos, especialmente a Mt e a Mg; podendo ainda associá-los com os atributos do solo. É possível elaborar um protocolo alternativo de necessidade de calagem, utilizando os valores de SM e os teores de argila do solo. Soil acidity is a limiting factor for agricultural production. Liming is a viable alternative to increase the levels of pH, Ca, Mg and saturation by soil bases. In order to have efficient correction recommendations, it is necessary to know the soil attributes and relate them to the spatial variability of the area. The objective of this work was to estimate the soil liming requirement by the magnetic signature and to determine specific management areas. 100 soil samples were collected in180 ha - area, in Alpinópolis - MG. Samples were submitted to soil granulometric, chemical, mineralogical and magnetic susceptibility analysis (SM). Magnetic soil minerals, magnetite (Mt) and magemite (Mh) quantification was used by SM before and after treatment with addition sodium citrate bicarbonate. The results were submitted to descriptive, geostatistical and regression tree analysis. Based on the available database, the magnetic signature makes it possible to accurately estimate the need for liming using a regression tree. The spatial pattern of the SM soil makes it possible to recognize areas with different potential for liming requirements. This consolidates the analysis as an indirect and promising tool in the definition of specific management areas and in the tactical and operational planning of agricultural activities that pursue increases in crop productivity. It was possible to develop an alternative liming requirement protocol, using magnetic susceptibility values and soil clay contents. A soil SM allows to differentiate the origin of magnetic signals in pedogenetics, especially Mt and Mg; it can also be associated with soil attributes. It is possible to elaborate an alternative liming requirement protocol, using the values of SM and the clay content of the soil. CAPES: 001

Made available in DSpace on 2019-10-06T16:41:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-25 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Pró-Reitoria de Pesquisa, Universidade Federal do Rio Grande do Sul Universidade Estadual Paulista The demand for information on the soil resource to support the establishment of public policies for land use and management has grown exponentially in the last years. However, there are still difficulties to the proper use of already existing information for soil mapping. Here we aimed to establish a protocol for soil mapping using legacy data, magnetic signature and soil attributes evaluation. A total of 493 soil samples were collected at 0–0.20 m in the geological domain of Western Plateau of São Paulo State. This work has three parts: First, we performed a classification analysis using soil mapping units (SMU) extracted from conventional soil map and Support Vector Machines algorithm (SVM). As covariates, we used categorical information, such as geology, dissection and landform maps. Second, we used soil attributes to perform a cluster analysis using k-means as partitioning method. To choose the optimal number of clusters, the same number of SMU showed in the conventional soil map (e.g. 34 clusters) were used. The last step was to compare soil and clusters maps predicted by SVM with the conventional soil map. Results showed good performance of SVM for both classifications (clusters and SMU), with overall accuracy of 0.60 and 0.90 respectively. In addition, the distribution of soil attributes within each cluster was more homogeneous and well distributed than within SMU, showing that is very possible to use numerical classification for soil mapping. Future soil surveys could use cluster analysis as a preliminary evaluation for better understanding of tropical soil variations. Dep. of Soils and Fertilizers State University of São Paulo (UNESP) Soil Characterization for Specific Management Research Group (CSME), Jaboticabal Agronomic Institute of Campinas, Campinas Dep. of Vegetal Production State University of São Paulo (UNESP), Jaboticabal Dep. of Soils and Fertilizers State University of São Paulo (UNESP) Soil Characterization for Specific Management Research Group (CSME), Jaboticabal Dep. of Vegetal Production State University of São Paulo (UNESP), Jaboticabal

We review the nature and importance of soil factors implicated in the formation of secondary ferrimagnetic minerals in soils and palaeosols worldwide. The findings are examined with respect to temperate regions through a comprehensive analysis of over 5000 samples of surface soil from England and Wales taken from a 5 × 5 km grid. Over 30 soil and environmental attributes are considered for each sample as proxies for soil forming factors. Measurements of low field magnetic susceptibility (mass specific) and frequency dependent susceptibility (mass specific and percentage) on each sample provide estimates of the concentration and grain size of ferrimagnetic minerals. Maps of soil magnetism across England and Wales show non-random distributions and clusters. One subset of data is clearly linked to contamination from atmospheric pollution, and excluded from subsequent analyses. The concentration of ferrimagnetic minerals in the non-polluted set is broadly proportional to the concentration of minerals falling into the viscous superparamagnetic domain size range (~ 15–25 nm). This set shows clusters of high magnetic concentrations particularly over specific parent materials such as schists and slates, mudstones and limestones. Bivariate analyses and linear multiple regression models show that the main controlling factors are parent material and drainage, the latter represented by soil drainage classes and particle size. Together these two factors account for ~ 30% of the magnetic variability in the complete dataset. A second group of factors, including climate (mean annual rainfall), relief (slope and altitude), and organisms (land use, organic carbon and pH) have subordinate control. Climate, as represented by mean annual temperature, and also pedogenic time are deemed not relevant at these spatio-temporal scales. The findings are consistent with a largely abiotic system where the role of iron-reducing bacteria appears minor. At coarse spatial and temporal scales, secondary ferrimagnetic mineral formation is controlled by the weathering capacity to supply Fe to the surface soil. At finer scales, soluble Fe precipitates as ferrihydrite before transformation in response to periodically anaerobic conditions into other minerals including nanoscale magnetite.

Soil profiles of the Kathmandu urban area exhibit significant variations in magnetic susceptibility (χ) and saturation isothermal remanence (SIRM), which can be used to discriminate environmental pollution. Magnetic susceptibility can be used to delineate soil intervals by depth into normal (

Introduction A widely spread Celtic archaeological feature in southern Germany, ranging from eastern France to the western Czech Republic, are the so called “Viereckschanzen” or “Square Enclosures”, dating to the La Tène period 200 to 50 B.C. They consist of nearly square systems of earth walls with only one entrance gap and uninterrupted surrounding ditches. Inside these enclosures traces of buildings are known. Since 1993 more than 20 magnetometer surveys have been carried out. In order t...