Sabino Pereira da Silva Neto

Spatial analysis of parameters of soil fertility in an ecotone under different uses and management

In regions of ecotone soil chemical properties show a wide variation, resulting from the interplay between the factors of formation, vegetation cover and use. The aim of this study was to evaluate the spatial variability of chemical attributes of a Entisol transition zone between the Savannah and Amazonian biome in different forms of land use and management (forest, scrub, bare soil, crop, pasture and savanna) in the region of Araguaina city (TO). Samples were ground in an irregular mesh in an area of 26.08 ha, the depth of 0 to 20 cm to determine the levels of organic matter, P, K + , Ca 2+ , Mg 2+ and pH, sum of bases, CEC pH 7 , CEC e , V%, m%. The soil chemical properties were analyzed using descriptive statistics, comparison of average by Tukey test at 5% significance to the study and geostatistical kriging. The ranges of spatial dependence of the chemical organic matter, Al 3+ , K + , Mg + , and SB CEC e soil were higher than the others (pH, P, Ca 2+ , CEC pH 7 , V%, m%), indicating that these are more discontinuity in the spatial distribution in Entisol three forms of agricultural use and vegetation cover three of the transition Savannah-Amazon. Thus, management strategies of correction and mineral fertilizers in an ecotone can be fitted according to the representations of studies and geostatistical kriging interpolation in homogeneous areas.

Integrating forest-pasture: Spatial analysis and delineation of zones of litter production and nutrient return

This study aimed to quantify, describe, and identify plant litter production and nutrient accumulation zones in different forest-pasture integration (FPI) systems and forest strata of the Cerrado-Amazon transition on typical orthic Quartzarenic Neosol using spatial analysis, principal component analysis, and non-hierarchical fuzzy k-mean clustering logic techniques. The evaluations were performed at two FPI systems comprising a combination of Brachiaria brizantha cv. Marandu and thinned native vegetation with 50 and 75% (FPI-I and FPI-II, respectively) shade in an original thinned forest (NFI) and in an original intact forest (NF-II) with 80 and 95% shade, respectively. An area of 4,000 m² (40 x 100 m) that contained 32 sampling points arranged in a 4 x 25 m grid was demarcated for each treatment. Plant litter was collected using 32 collectors installed at equidistant points. Twelve nylon bags were placed on the soil surface at each point to evaluate the plant litter decomposition, totaling 384 bags per treatment. It was possible to quantify, describe, and define plant litter production and nutrient accumulation zones in different FPI systems and forest strata of the Cerrado-Amazon transition on orthic Quartzarenic Neosol using geostatistical analysis, principal components, and non-hierarchical fuzzy k-mean clustering logic procedures.

Dependência espacial em levantamentos do estoque de carbono em áreas de pastagens de Brachiaria brizantha cv. Marandu

Foi conduzido um estudo utilizando analise de semivariogramas para quantificar a autocorrelacao espacial dos estoques de carbono (EC) no solo, biomassa da graminea e das plantas daninhas em tres parcelas experimentais de pastagens de Brachiaria brizantha cv. Marandu com niveis baixo, medio e alto de degradacao, cultivadas em Neossolo Quartzarenico Ortico. As coletas das plantas e do solo foram realizadas em malha de amostragem regular com distâncias de 5 x 5 m em area de 900 m². Os EC das pastagens foram submetidos as analises de estatistica descritiva, ao teste nao-parametrico de Kruskal-Wallis ao nivel de 5% de significância, ao estudo geoestatistico e interpolacao por krigagem ordinaria. A variabilidade espacial do EC foi observada dentro e entre as pastagens de capim-Marandu com niveis baixo, medio e alto de degradacao. A pastagem de capim-Marandu com nivel baixo de degradacao teve menor continuidade espacial, por apresentar menores alcances no EC, na biomassa da graminea e na biomassa total (graminea + plantas daninhas), no solo e no sistema solo x pastagem (solo + biomassa total). A grade de 5 x 5 m foi adequada para caracterizar a variabilidade espacial de pastagens de capim-Marandu com niveis de degradacao baixo e alto. Area de pastagem de capim-Marandu com grau medio de degradacao apresenta coeficientes de variacao altos entre os valores EC; o que comprometeu a modelagem espacial que tambem pode ter ocorrido devido ao baixo numero de amostras realizadas (n=36). Assim, pontos de amostragem menores que 5 m podem melhorar a precisao dos ajustes dos semivariogramas.

Spatial variation and area definition of nutrient extraction by Marandu grass biomass

The present study aimed to quantify, describe and identify areas of nutrient extraction by Brachiaria brizantha cv. Marandu biomass in integrated forest-pasture systems from a Cerrado-Amazon transition region with Typic Quartzipsamment soil by using geostatistical techniques, principal components analysis and non-hierarchical fuzzy k-means clustering. The evaluations were conducted in two integrated forest-pasture systems from an association with Brachiaria brizantha cv. Marandu and native 1 Prof., Instituto Federal de Educação, Ciência e Tecnologia do Tocantins, Gurupi, TO, Brasil. E-mail: sabino.pereira@ifto.edu.br 2 Profs., Fundação Universidade Federal do Tocantins, Araguaína, TO, Brasil. E-mail: clementino@mail.uft.edu.br; e_alexandrino@ yahoo.com.br; araguaia2007@gmail.com; jgsanttos@gmail.com; jecs@uft.edu.br 3 Prof., Instituto Federal de Educação, Ciência e Tecnologia do Tocantins, Araguatins, TO, Brasil. E-mail: laerton.leite@ifto.edu.br * Author for correspondence

Integração floresta-pasto: análise espacial e delineamento de zonas de produção de serapilheira e retorno de nutrientes

This study aimed to quantify, describe, and identify plant litter production and nutrient accumulation zones in different forest-pasture integration (FPI) systems and forest strata of the Cerrado-Amazon transition on typical orthic Quartzarenic Neosol using spatial analysis, principal component analysis, and non-hierarchical fuzzy k-mean clustering logic techniques. The evaluations were performed at two FPI systems comprising a combination of Brachiaria brizantha cv. Marandu and thinned native vegetation with 50 and 75% (FPI-I and FPI-II, respectively) shade in an original thinned forest (NFI) and in an original intact forest (NF-II) with 80 and 95% shade, respectively. An area of 4,000 m² (40 x 100 m) that contained 32 sampling points arranged in a 4 x 25 m grid was demarcated for each treatment. Plant litter was collected using 32 collectors installed at equidistant points. Twelve nylon bags were placed on the soil surface at each point to evaluate the plant litter decomposition, totaling 384 bags per treatment. It was possible to quantify, describe, and define plant litter production and nutrient accumulation zones in different FPI systems and forest strata of the Cerrado-Amazon transition on orthic Quartzarenic Neosol using geostatistical analysis, principal components, and non-hierarchical fuzzy k-mean clustering logic procedures.