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All publications of “Sandra Cátia Pereira Uchôa”

5 results

Effect of Harvest Time and Nitrogen Doses on Cassava Root Yield and Quality

Natália Trajano de Oliveira, Sandra Catia Pereira Uchôa, José Maria Arcanjo Alves, José de Anchieta Alves de Albuquerque, Guilherme Silva Rodrigues


ABSTRACT Nitrogen is considered the most limiting nutrient for cassava, and N availability can influence the crop cycle, including earlier harvest. The aim of this study was to study the effect of harvest time on the production components of cassava, “Aciolina” cultivar, at different rates of N fertiliser. The experiment was carried out in an area newly incorporated into the productive system in a savannah ecosystem in the northern Amazon. A randomised block experimental design was used in a split […]

Characterization of Organic Matter under Different Pedoenvironments in the Viruá National Park, in Northern Amazon

José Frutuoso do Vale, Steven Nicodem, Valdinar Ferreira Melo, Sandra Catia Pereira Uchôa, Diego Lima de Sousa Cruz


ABSTRACT Soil organic matter (SOM) fractions result from a variety of environmental processes, which affect incorporation and production rates, decomposition, alteration, and/or mineralization of organic matter. The aim of this study was to characterize SOM under the environments of rain forest, wooded campinarana (grasslands), arboreal-shrubby campinarana, grassy-woody campinarana, and pioneer plants of the Viruá National Park, in the north of the Brazilian Amazon. After chemical and physical characterization and soil classification, total organic carbon (TOC), total N, microbial activity, organic […]

Effect of sulphur rates and incubation time on the dynamics of sulphur forms in soil

Sandra Cátia Pereira Uchôa, Alvarez V. Víctor Hugo, Francisco Morel Freire


Sulphur availability depends on the dynamics of its soil forms. An experiment was carried out to evaluate the effects of adding sulphur doses (0, 20, 50, 80, and 120 mg dm-3 of S), as calcium sulphate, and the incubation time (1, 8, 15, 30, 60, and 90 d) on the equilibrium between labile and non-labile sulphur reserves, in 10 soils. An anion exchange resin membrane was used to determine labile sulphur. A shaking period of 48 h (of water, soil […]

Genesis, chemistry and mineralogy of soils derived from Plio-Pleistocene sediments and from volcanic rocks in Roraima North Amazonia

Udine Garcia Benedetti, José Frutuoso do Vale Júnior, Carlos Ernesto Gonçalves Reynaud Schaefer, Valdinar Ferreira Melo, Sandra Cátia Pereira Uchôa


The influence of parent material, varying from Plio-Pleistocene sediments and basic volcanics, and topographic position, to soil genesis, was studied in a topolitossequence typical of savanna at the Cauamé River catchment, Roraima. We aimed to describe the soil variability under savanna by means of chemical, physical and mineralogical attributes. Fourteen soil profiles were described and samples, allowing the identification of the following classes: Yellow Latosol, Red Latosol, Yellow and Red-Yellow Argisols, Plinthosols, Gleisols, Fluvic Neosols and Vertisols. The mineralogy was […]

Soils in the Yanomami indigenous area in the mid-Catrimani River – Roraima

Valdinar Ferreira Melo, Marcio Rocha Francelino, Sandra Cátia Pereira Uchôa, Samara Salamene, Célida Socorro Vieira dos Santos


In Roraima, the spatial distribution of indigenous peoples indicates a background of constant search for soils capable of sustaining shift cultivation. This study aimed to establish a relationship between the understanding of soil by the Yanomami tribe from the mid-Catrimani river region and the Brazilian System of Soil Classification and evaluate the type of agricultural land use according to soil fertility tests, in two steps. The first consisted of visiting eight Indian communities to collect soil samples at 21 sites […]