Variabilidade da agregação em amostras de solos agrícolas como indicador de qualidade: uma proposta metodológica
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Data
2018-03-02
Autores
Peche Filho, Afonso
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As questões ambientais que envolvem os efeitos do manejo e da degradação do solo necessitam de forma acelerada de pesquisa e muita extensão. Novos saberes e conhecimentos têm alcançado parte da comunidade acadêmica, mas ainda está aquém das necessidades para técnicos e leigos envolvidos em trazer soluções para problemas da ocupação, uso e degradação das terras. O manejo e recuperação ambiental de áreas degradadas são complexos e requerem diferentes tecnologias para o diagnóstico e avaliação. O uso de indicadores como diâmetro médio geométrico e distribuição percentual de agregado são parâmetros de uso consolidados, mas trazem limitações para questões complexas como o diagnostico do estado e condição de agregação do solo. A agregação do solo vem sendo estudada desde o inicio do século passado, mas são poucos os avanços conseguidos em popularizar a analise de agregação do solo agrícola como uma ferramenta laboratorial e prática. Além de que, falta conhecimento para popularizar a condição de agregação como informação de uso corrente. O uso de imagens obtidas e processadas em alta resolução permite sua aplicação em diferentes ramos da ciência, podendo ser aplicada nos estudos relacionados com o processo de agregação permitindo viabilizar o mais conhecimento ao processo. Este trabalho tem como objetivo desenvolver uma proposta metodológica para determinar a condição da qualidade de agregação, com base na tipificação de agregados e nos efeitos da variabilidade de composição em amostras de solo agrícola. Foram utilizados parâmetros relacionados com a forma, superfície e biogênese de agregados como indicadores de variabilidade da agregação do solo em duas amostras de latossolo vermelho de textura média, sendo que uma delas é referente a uma parcela de solo que recebeu um produto fertilizante/agregante Microgeo® e outra parcela sem ter recebido o produto. A obtenção dos agregados foi através do processo de peneiramento via seca utilizando cinco peneiras de diferentes calibres. A análise de agregados foi realizada em laboratório a partir de uma sub-amostra contendo 100 agregados oriundos de cada peneira específica, totalizando 500 agregados por amostras individuais de solo, perfazendo um total de 1000 agregados avaliados. A partir da obtenção de 1000 imagens fotográficas, com auxílio de um programa de processamento de imagens, obtêm-se um banco de dados referentes aos parâmetros morfométricos. Através do uso de tecnologia Fuzzy obteve-se um banco de dados numéricos referente à tipificação com base na análise visual da forma, superfície e biogênese dos agregados. Para cada conjunto de dados foi elaborado uma representação gráfica da variabilidade e seu respectivo quadro analítico descritivo. Com auxílio de medidas separatrizes do tipo quintis os dados foram classificados de acordo com a tipologia de ocorrência. Foram utilizados como parâmetros morfométricos o “diâmetro de Feret”, e como parâmetro de tipificação rugosidade de superfície e a “saída Fuzzy de tipificação” (os valores de integração com uso da tecnologia Fuzzy) o qual denominamos “Indicie Fuzzy de Tipificação”. Os resultados permitem afirmar que o trabalho atendeu os objetivos proposto de oferecer para sociedade uma “metodologia para qualificar a agregação em amostras de solos agrícolas”. Os resultados permitem aceitar as hipóteses formuladas e concluir que o estudo sobre efeitos da variabilidade permite quantificar, diagnosticar e qualificar o estado de agregação de amostras de solo.
Environmental issues involving the soil management effects and degradation are increasing and need to be extensively researched to be managed. New knowledge about solutions has been produced by academic research, but is still insufficient to solve the problems faced by technicians and other people involved to the field land use planning and degradation problems. Furthermore, the management of soil quality and land reclamation is complex, requiring different technologies for diagnosis and evaluation. The use of indicators, such as geometric mean diameter and percentage distribution of aggregate size, represents classical approaches, but both have limitations in treating the complexity of soil aggregation process. The soil aggregation has been studied since the beginning of the last century, but few advances have been made to popularize it to analyze agricultural soil quality. There are several difficulties to develop laboratory routines and practical tool to evaluate it. The use and processing of high resolution images have been widely applied in several fields of science and represents an interesting solution to study soil aggregation. To fill the existing gap, this works presents a methodological proposal to assess the quality of soil aggregation, by a classification of soil aggregates in terms of composition and variability. Agricultural soil aggregates were analyzed by three attributes: shape, surface and biogenesis. These parameters were used as indicators of soil aggregation quality, and the variability on each parameter was evaluates for two samples of medium texture red latosol, one of them referring to a plot of soil that received a fertilizer/aggregate product Microgeo® and another without receiving it. The aggregates were passed through the dry sieving process using five different sizes. The laboratorial analysis was performed by subsampling 100 aggregates from each sieve, totaling 500 aggregates per soil samples, and making a total of 1000 aggregates. Each soil aggregate was photographed, totalling1000 pictures, later processed on ImageJ. All results were organized in a database, containing information about the morphometric parameters of all soil aggregates. Fuzzy Logic was employed to transform the aggregate type into numeric values, using the visual analysis of the shape, surface and biogenesis. For each data set, a graphical representation of the variability and its descriptive statistics were calculated, producing an analytical framework. Statistical measures were used to classify the samples according to occurrence of aggregate type. To classify the samples and two sets of indexes were developed. The first one was based on the "Feret diameter", used as morphometric indicator, and the second one based on the "Fuzzy typing output", index produced by the integration of the values of shape, surface and biogenesis by a Fuzzy Inference System, which we call "Fuzzy index of typing". These results allowed affirming that the work fulfill the proposed objectives, offering to society a "methodology to qualify the aggregation quality in samples of agricultural soils". The results also allowed us to accept the formulated hypotheses and conclude that the study of variability can be used to quantify, diagnose and qualify the state of aggregation of soil samples.
Environmental issues involving the soil management effects and degradation are increasing and need to be extensively researched to be managed. New knowledge about solutions has been produced by academic research, but is still insufficient to solve the problems faced by technicians and other people involved to the field land use planning and degradation problems. Furthermore, the management of soil quality and land reclamation is complex, requiring different technologies for diagnosis and evaluation. The use of indicators, such as geometric mean diameter and percentage distribution of aggregate size, represents classical approaches, but both have limitations in treating the complexity of soil aggregation process. The soil aggregation has been studied since the beginning of the last century, but few advances have been made to popularize it to analyze agricultural soil quality. There are several difficulties to develop laboratory routines and practical tool to evaluate it. The use and processing of high resolution images have been widely applied in several fields of science and represents an interesting solution to study soil aggregation. To fill the existing gap, this works presents a methodological proposal to assess the quality of soil aggregation, by a classification of soil aggregates in terms of composition and variability. Agricultural soil aggregates were analyzed by three attributes: shape, surface and biogenesis. These parameters were used as indicators of soil aggregation quality, and the variability on each parameter was evaluates for two samples of medium texture red latosol, one of them referring to a plot of soil that received a fertilizer/aggregate product Microgeo® and another without receiving it. The aggregates were passed through the dry sieving process using five different sizes. The laboratorial analysis was performed by subsampling 100 aggregates from each sieve, totaling 500 aggregates per soil samples, and making a total of 1000 aggregates. Each soil aggregate was photographed, totalling1000 pictures, later processed on ImageJ. All results were organized in a database, containing information about the morphometric parameters of all soil aggregates. Fuzzy Logic was employed to transform the aggregate type into numeric values, using the visual analysis of the shape, surface and biogenesis. For each data set, a graphical representation of the variability and its descriptive statistics were calculated, producing an analytical framework. Statistical measures were used to classify the samples according to occurrence of aggregate type. To classify the samples and two sets of indexes were developed. The first one was based on the "Feret diameter", used as morphometric indicator, and the second one based on the "Fuzzy typing output", index produced by the integration of the values of shape, surface and biogenesis by a Fuzzy Inference System, which we call "Fuzzy index of typing". These results allowed affirming that the work fulfill the proposed objectives, offering to society a "methodology to qualify the aggregation quality in samples of agricultural soils". The results also allowed us to accept the formulated hypotheses and conclude that the study of variability can be used to quantify, diagnose and qualify the state of aggregation of soil samples.
Descrição
Palavras-chave
Análise laboratorial, Agregados, Áreas degradadas, Avaliação ambiental, Física de solos, Laboratory analysist, Soil aggregates, Soil degradation, Environmental quality assessment, Soil physics