Valdinéia Patricia Dim

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.

Características agronômicas, estruturais e bromatológicas do capim Piatã em lotação intermitente com período de descanso variável em função da altura do pasto

Objective was to evaluate the influence of different grazing height on agronomic, structural and qualitative characteristics of Brachiaria brizantha cv. Piata managed under rotational stocking. We evaluated three sward heights (30, 45 and 60 cm) over two growing seasons (Middle and Final Season). We adopted the randomized complete block design with split plot, where the plots were allocated heights and subplots the growing seasons. Height values met the experimental protocol, showing averages of 35.2; 43.5 and 59.4, respectively 30, 45 and 60 cm. The rest period was variable during the heights and providing different grazing cycles, with an average DP of 34, 39 and 54 days, respectively, to the heights studied . The highest yield obtained by MST cycle was at the height of 60 cm, with an average of 4612.51 kg ha-1 and 3566 kg ha-1 to 30 cm height. However the heights of 30 and 45 cm three cycles of grazing and only two to the height of 60 cm were obtained, totaling about it, 12.4, 10.7 and 9.2 t DM ha-1 in the period. In leaf/stem ratio, no differences in heights studied. The number of tillers did not change with different heights, the superiority in the number of tillers was observed in the middle of the growing season. The increase in sward height provided no change in CP content and digestibility and increased levels of ADF, NDF was changed only at the height of 60 cm.

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.