Spacial Variability and Sampling Density of Chemical Attributes in Archaeological Black Earth and Native Forest Soil in Manicoré, Am

Abstract

Considering the lack of information about spatial behavior of the soil attributes in areas of archaeological black earth and native forest, the objective of this study was to evaluate the spatial variability of chemical attributes and determine the sampling density in soil with archaeological black earth and native forest in the region of Manicoré, AM. The study was conducted in a rural property located in the community of Santo Antônio do Matupi, at the margins of BR 230, Trans-amazon highway, in the region of Manicoré, AM. In these areas were established grids of 70 m x 70 m, with regular spacing of 10 x 10 m, totaling 64 points, then soil samples were collected at a depth of 0.0-0.20 m and 0 , 40 -0,60 m. Chemical attributes were determined (pH, OM, P, K, Ca, Mg, SB, CTC, V% and H + Al). Data were analyzed using descriptive statistical techniques and geostatistics. Sampling density was determined basing on CV and on the range of the semivariograms. It was verified that the studied attributes showed spatial variability and the area of archaeological black earth presented greater spatial variability than the native forest. Its greater sampling density was determined basing on the range of the adjusted semivariograms. Keywords: Indian black earth; attributes of soil; geostatistics. ResumoVariabilidade espacial e densidade amostral de atributos químicos em solo de terra preta arqueológica e floresta nativa em Manicoré, AM. Considerando a falta de informações sobre o comportamento espacial dos atributos do solo em áreas de terras pretas arqueológicas ou terras pretas de índio e floresta, o objetivo deste trabalho foi avaliar a variabilidade espacial de atributos químicos e determinar a densidade amostral em solo com terra preta arqueológica e floresta nativa na região de Manicoré, AM. O estudo foi realizado em uma propriedade rural localizada na comunidade de Santo Antônio do Matupi, às margens da BR 230, rodovia Transamazônica, região de Manicoré, AM. Nestas áreas foram estabelecidas malhas de 70 m x 70 m, com espaçamento regular de 10 x 10 m totalizando 64 pontos e em seguida, coletadas amostras de solos na profundidade de 0,0-0,20 m e 0,40 -0,60 m. Foram determinados os atributos químicos (pH em água, MO, P, K, Ca, Mg, SB, CTC, V% e H+Al). Os dados foram analisados utilizando-se técnicas de estatística descritiva, geoestatística e determinado a densidade amostral com base no CV e no alcance dos semivariogramas. Verificou-se que os atributos estudados apresentaram variabilidade espacial e a área de terra preta arqueológica apresentou maior variabilidade espacial em relação à floresta nativa, apresentando maior densidade amostral baseados no alcance dos semivariogramas ajustados. Palavras-chave: Terra preta de índio; atributos do solo; geoestatística.

Sampling of Chemical Attributes in Forest Soils

“…It is important to emphasize the need to control sample and non-sample errors to minimize variation in soil properties. Non-sampling errors occur when samples are collected, recorded or analyzed erroneously, giving rise to values that deviate from the central tendency (SHIVER;BORDERS, 1996;HEIM et al, 2009;OLIVEIRA et al, 2014). Different instruments and collection professionals, nutrient mobility, irregularity of factors responsible for pedogenesis and inappropriate soil management contribute to the variability of the analytical results (ACQUA et al, 2013;NICOLITCH et al, 2016;TIAN et al, 2017).…”

“…Corrective and fertilizer recommendations are based on information from sampling procedures that, if properly carried out, contribute to desired forest productivity achievement. The samples should be collected in a planned manner and adequately represent the fertility of the site to be fertilized (HEIM et al, 2009;OLIVEIRA et al, 2014). The distribution of the sample units needs to be performed in sufficient quantity so that the estimates of nutrient averages are accurate and reliable (CANTARUTTI et al, 1999;BRUS, 2015).…”

“…The random or zigzag distribution of collection points is extensively used to obtain simple soil samples. In this perspective, several surveys have contemplated the analysis of chemical attributes representativeness applying simple random sampling or geostatistical analysis (HEIM et al, 2009;LIMA et al, 2010;OLIVEIRA et al, 2014;OLIVEIRA et al, 2015, GUARÇONI et al, 2017. It is emphasized that the strata definition is a laborious task compared to the unrestricted sample units distribution, but it has great potential for sample error control (SHIVER; BORDERS, 1996).…”

Spatial variability and sampling density of chemical attributes in archaeological black earths under pasture in southern Amazonas, Brazil

“…The exploitation of regional potential is one of the alternatives to ensure a sustainable agricultural success (Oliveira et al, 2014, Gomes et al, 2017. In this scenario are inserted the archaeological black earths (ABEs) or Indian black earths present in the Amazonian landscape.…”

“…Although some studies have focused on the characterization of ABE attributes (Aquino et al, 2016), few of them have investigated the spatial pattern of its chemical attributes due to the great territorial dimension and diversity of soil, relief, and vegetation of the Amazonas State. In order to take advantage of the regional natural resources without depleting soil chemical quality, it is essential to know the spatial variability of its attributes (Oliveira et al, 2014) since it is a complex interaction of factors and processes of formation, having as additional sources the management of soil, crop, and landscape variations (Campos et al, 2012;Roger et al, 2014;Brito et al, 2018). Thus, agricultural success or an adequate and efficient soil management can only be possible when the spatial pattern of its attributes is defined (Gomes et al, 2017).…”