Qual o desempenho de densidades amostrais e interpoladores para elaboração de mapas de calagem em Argissolo?
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Data
2020-07-08
Autores
Miranda, Isabella Dinardo
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Universidade Estadual Paulista (Unesp)
Resumo
O conhecimento detalhado da propriedade agrícola, por meio de amostragens e análises de solo, permite a obtenção da correta distribuição espacial dos atributos do solo. Tal conhecimento é relevante para o planejamento agrícola, uma vez que identifica as necessidades de correção do solo e permite a aplicação localizada de insumos. Os objetivos do presente trabalho foram avaliar a influência do número de pontos amostrados e do interpolador empregado na qualidade dos mapas de CTC, V% e necessidade de calcário e de estimar o número ideal de pontos para amostragens de solo georreferenciada em dois argissolos cultivados com cana-de-açúcar, para que ocorra uma minimização dos erros nos mapas gerados. As duas áreas amostradas estão localizadas no centro-oeste do estado de São Paulo, sendo uma delas (Área A) de 313,53 ha, no munícipio de Pongaí/SP e a outra (Área B), de 312,40 ha, no munícipio de Cafelândia/SP. Foram coletadas amostras compostas por 10 subamostras, em duas profundidades (0-0,25 m e 0,25-0,50 m), na densidade amostral de 1:1 ha. As amostras foram encaminhadas ao laboratório para análise química, visando a determinação dos parâmetros de fertilidade do solo. Foram calculados os parâmetros CTC e saturação por bases (V%). Posteriormente, por meio da exclusão de pontos, foram obtidas diferentes densidades amostrais (1:2, 1:3, 1:4 e 1:5). Os dados de CTC e V% em cada densidade amostral foram então submetidos às análises estatística descritiva e geoestatística e os mapas de distribuição espacial desses dois parâmetros de solo foram gerados tanto por interpolação por krigagem quanto pelo inverso do quadrado da distância. Foram também gerados mapas de aplicação de calcário para as diferentes densidades amostrais e pelos dois interpoladores. Comparando os mapas interpolados de V% e CTC e os mapas de aplicação de calcário das duas áreas conclui-se que se deve utilizar densidade amostral de 1:2 ha e inverso do quadrado da distância como interpolador.
Detailed knowledge of the agricultural property, through sampling and soil analysis, allows obtaining the correct spatial distribution of soil attributes. Such knowledge is relevant to agricultural planning, since it identifies the needs for soil correction and allows the localized application of agricultural inputs. This work aimed to evaluate the influence of the number of sampled points and the interpolator used on the quality of the CTC, V% maps and the need for limestone in two argisols grown with sugarcane, and to estimate the ideal number of points for soil sampling georeferenced in argisols, so that errors in the generated maps are minimized. The two sampled areas are located in the center-west of the state of São Paulo, one of them (Area A) of 313.53 ha, in the county of Pongaí/SP and the other (Area B), of 312.40 ha, in the county of Cafelândia/SP. Composite samples were collected at two depths (0-0.25 m and 0.25- 0.50 m), at a sampling density of 1: 1 ha. The samples were sent to the laboratory for chemical analysis, in order to determine the soil fertility parameters. The CTC parameters and base saturation (V%) were calculated. Subsequently, different sample densities (1: 2, 1: 3, 1: 4 and 1: 5) were obtained by excluding points. CTC and V% data were submitted to descriptive statistical and geostatistical analyzes and the maps of those two soil parameters were created by interpolation analyzes by kriging and by the inverse of the square of the distance. Limestone application maps were also generated for the different sample densities and by the two interpolators. Comparing the V% and CTC interpolated maps and the limestone application maps of the two areas, it is concluded that the sample density of 1: 2 ha and inverse of the square of the distance should be used as interpolator.
Detailed knowledge of the agricultural property, through sampling and soil analysis, allows obtaining the correct spatial distribution of soil attributes. Such knowledge is relevant to agricultural planning, since it identifies the needs for soil correction and allows the localized application of agricultural inputs. This work aimed to evaluate the influence of the number of sampled points and the interpolator used on the quality of the CTC, V% maps and the need for limestone in two argisols grown with sugarcane, and to estimate the ideal number of points for soil sampling georeferenced in argisols, so that errors in the generated maps are minimized. The two sampled areas are located in the center-west of the state of São Paulo, one of them (Area A) of 313.53 ha, in the county of Pongaí/SP and the other (Area B), of 312.40 ha, in the county of Cafelândia/SP. Composite samples were collected at two depths (0-0.25 m and 0.25- 0.50 m), at a sampling density of 1: 1 ha. The samples were sent to the laboratory for chemical analysis, in order to determine the soil fertility parameters. The CTC parameters and base saturation (V%) were calculated. Subsequently, different sample densities (1: 2, 1: 3, 1: 4 and 1: 5) were obtained by excluding points. CTC and V% data were submitted to descriptive statistical and geostatistical analyzes and the maps of those two soil parameters were created by interpolation analyzes by kriging and by the inverse of the square of the distance. Limestone application maps were also generated for the different sample densities and by the two interpolators. Comparing the V% and CTC interpolated maps and the limestone application maps of the two areas, it is concluded that the sample density of 1: 2 ha and inverse of the square of the distance should be used as interpolator.
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Palavras-chave
Geoestatística, Agricultura de Precisão, Pontos Georreferenciados