Use of Scaled Semivariograms in the Planning Sample of Soil Physical Properties in Southern Amazonas, Brazil

Abstract

There is a great lack of information from soil surveys in the southern part of the State of Amazonas, Brazil. The use of tools such as geostatistics may improve environmental planning, use and management. In this study, we aimed to use scaled semivariograms in sample design of soil physical properties of some environments in Amazonas. We selected five areas located in the south of the state of Amazonas, Brazil, with varied soil uses, such as forest, archaeological dark earth (ADE), pasture, sugarcane cropping, and agroforestry. Regular mesh grids were set up in these areas with 64 sample points spaced at 10 m from each other. At these points, we determined the particle size composition, soil resistance to penetration, moisture, soil bulk density and particle density, macroporosity, microporosity, total porosity, and aggregate stability in water at a depth of 0.00-0.20 m. Descriptive and geostatistical analyses were performed. The sample density requirements were lower in the pasture area but higher in the forest. We concluded that managed-environments had differences in their soil physical properties compared to the natural forest; notably, the soil in the ADE environment is physically improved in relation to the others. The physical properties evaluated showed a structure of spatial dependence with a slight variability of the forest compared to the others. The use of the range parameter of the semivariogram analysis proved to be effective in determining an ideal sample density.

Técnicas geoestatísticas na avaliação de atributos químicos em Cambissolo com agrofloresta e cana-de-açúcar em Humaitá, Amazonas

“…Já os valores de alcance foram superiores na área de agrofloresta (42,11 e 33,33 m) respectivamente, enquanto que na área com cana-de-açúcar (38,10 e 18,18 m) respectivamente, confirmando a maior variabilidade espacial já encontrada nos semivariograma individuais. Trabalhos de Aquino et al (2015) e Oliveira et al (2015) desenvolvidos na região sul do Amazonas estão de acordo com os encontrados neste trabalho.…”

“…Estas informações podem viabilizar o trabalho em campo, uma vez que vários estudos de amostragem têm sido conduzidos visando reduzir a variabilidade das características do solo (Montanari et al, 2005;Weindorf & Zhu, 2010;Aquino et al, 2014Aquino et al, , 2015Oliveira et al, 2014Oliveira et al, , 2015. Entretando, os trabalhos normalmente, não consideram a variabilidade das amostras simples na composição da amostra composta e a forma como as glebas são definidas.…”

“…Alguns trabalhos têm sido desenvolvidos no estado do Amazonas, visando entender o comportamento dos atributos do solo sobre o ponto de vista espacial na região norte (Campos et al, 2012Alho et al, 2014;Aquino et al, 2014Aquino et al, , 2015Oliveira et al, 2014Oliveira et al, , 2015 entretanto, estes trabalhos ainda são incipientes dada a dimensão da região.…”

Physical and geospatial attributes of inceptisols and ultisols under native vegetation in Humaitá, AM, Brazil

“…Aquino et al (2015) and Campos et al (2011) asserted that terrain micro-variations can promote geospatial variation of soil attributes, even when the areas seem to be homogeneous (Oliveira et al, 2015a), affecting crop yield and soil analysis accuracy, which uses sample mean of the area. Moreover, Souza et al (2006) stated that extra statistical analyses are needed to measure such variations, because most of the soils change over time and space.…”

“…Within this context, geostatistical methods are being widely used, since they check the geographical coordinates of sample points in line with the soil properties within a geospatial domain (KAMIMURA et al, 2013;CORTEZ et al, 2011;SILVA et al, 2010) and, the occurrence of the assessed attributes enable the generation of kriging maps that display dynamics of soil attributes over the area, being an important aid for decision making regarding environmental and agricultural use (AQUINO et al, 2015;OLIVEIRA et al, 2013).…”