Valdinar Ferreira Melo

Gênese, química e mineralogia de solos derivados de sedimentos pliopleistocênicos e de rochas vulcânicas básicas em Roraima, Norte Amazônico

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 Cauame 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 determined by DRX. The pedogenetical processes and soil characteristics were closely related with topographical-hydrological variation and underlying lithology. Soils derived from pre-weathered sediments of the Boa Vista Formation are generally of low fertility, with high acidity and kaolinite mineralogy and low Fe-oxides contents. Soils developed from Basalt or under the influence of alluvia with mafic contribution all showed high base saturation (eutric) and clay mineralogy with the presence of 2:1 clays, with varying amounts of kaolinite. The occurrence of Vertisols, degraded carbonatic nodules and eutric soils under savanna indicate Quaternary drier paleoclimates in this part of north Amazonia, during which carbonates were formed in the lower horizons of Vertisols, in closed depressions.

Resposta do feijão-caupi à doses e formas de aplicação de fósforo em Latossolo Amarelo do Estado de Roraima

Phosphorus fertilization and ways of phosphate fertilizers application are important factors considering crop management. This study aimed at assessing the effect of phosphorus rates and phosphate fertilizers application forms on growth and phosphorus uptake of cowpea plants cropped on cerrado soil in the State of Roraima, Brazil. An experiment took place under field conditions, on a Yellow Latosol, at Cauame Campus of Roraimas Federal University, located in the municipality of Boa Vista/RR. The experimental design was split-plot, in a completely randomized blocks, with three replicates. The plots consisted of the following phosphoric fertilizers application forms: a) broadcasting; b) single furrow and c) double furrow. Sub-plots corresponded to phosphorus doses: 0, 0,5; 1,0; 1,5, and 2,0 times the recommended dose for cowpea maintenance fertilization (60 kg ha-1 of P2O5). There was a significant effect of P rates over plant growth and plant uptake. Application of fertilizer in double furrows promoted higher plant growth, grain yield, and plant phosphorous uptake.

Fitossociologia e características morfológicas de plantas daninhas após cultivo de milho em plantio convencional no cerrado de Roraima.

The Phytosociology is the floristic and structural study playing a very important role for the management of Weeds. The objective of this work was to study the phytosociology of weed after growing corn in conventional tillage in the savanna of Roraima. The phytosociological survey of soil management with crop rotation was conducted four months after the corn harvest in the period of May-June, 2010. For sampling was used an iron square with dimensions of 0.50 x 0.50 m, thrown randomly eight times in each corn plot, with area of 45 m 2 . Weeds were identified and quantified by the sum of two samples per plot. Evaluated variables: frequency, density, abundance, relative frequency, relative density, relative abundance, importance value index, fresh weight and dry weight of the species. Additionally, the botanical classes, families, species, type of propagation, life cycle, growth habit, the total number of species per ha -1 , and dry matter were described. Ninetten weed species were found in the area, separated into nine botanical families, being the Poaceae and Fabaceae with higher occurrences. 63.15% of the weed species belonging to the botanical class of Dicotyledons. Sida rhombifolia was the only species found in all sample collections. and C. echinatus was the most abundant species in the sample. The species with the highest importance value in the area were: Cenchrus echinatus, Sida rhombifolia Digitaria sanguinalis and Cyperus rotundus.

Caracterização física, química e mineralógica de solos da colônia agrícola do Apiaú (Roraima, Amazônia), sob diferentes usos e após queima

There are few studies on soils under slash-and-burn agriculture in settlements in Amazonia. The aim of this study was the soil characterization in the Apiau Agricultural Colony, Roraima, and to evaluate changes in some soil chemical properties in function of the management systems and the impacts of burning to the soil properties. The studied areas were: pastures, cultivated with banana and maize, burned forest and natural forest. The samples were submitted to physical chemical and mineralogical analysis. The soils are highly weathered Argisols, Latosols and Gleisols, all with kaolinitic mineralogy. The Argisols and Gleisols have low iron contents and high titanium oxides contents, and are highly weathered. The low exchangeable cations amounts determine the very low fertility, with high exchangeable aluminium saturation in the soils. The poor chemical status of the soils results in little variation between the different environments studied. The area cultivated with banana showed the highest values of exchangeable cations and available P in the surface horizon, due to organic matter mineralization after burning, and proximity to rock outcrops. The extreme chemical dystrophy in the degraded pastures is associated with abundance of weeds. The low total amounts of zinc indicate that zinc deficiency may occur, depending on which forms are present.

Doses de basalto moído nas propriedades químicas de um latossolo amarelo distrófico da savana de Roraima

Basaltic rocks have chemical and mineralogical composition that allows its agricultural application due to its capability of improving soil fertility. The aim in this work was to evaluate the effect of levels of finely crushed basalt rock in soil chemical conditioning. A dystrophic Yellow Latosol from pre-weathered Boa Vista Formation was used. The rock of the Apoteri formation was collected in the mine of Nova Olinda near Boa Vista. The treatments consisted of the incorporation and incubation of eight rock powder levels (0; 0.85; 1.70; 3.35; 5.03; 10.05; 20.40 and 40.80 g kg-1). The experimental design was entirely randomly with eight treatments and three replicates. After the incorporation of the rushed rock powder for a period 180 days of soil incubation, the soil was analyzed and determined the values of Ca2+, Mg2+, pH in H2O, pH in KCl, Al3+, H+ Al, Zn, Fe, Cu and Mn. The level of 20.40 g kg-1 of basalt provided the maxim reduction of the active acidity, varying from 4.8 to 5.5. Concentrations of exchangeable Ca2+ and Mg2+ increased, but their increments in the soil solution was small. Basalt levels presented high efficiency for neutralization of the potential acidity. Amendments with crushed rock increased extractable amounts of Zn, Fe and Cu in soil, after incubation.

SOLOS DA ÁREA INDÍGENA YANOMAMI NO MÉDIO RIO CATRIMANI, RORAIMA

Em Roraima, a distribuicao espacial das populacoes indigenas identifica um cenario de busca constante de solos capazes de sustentar uma agricultura itinerante. Este trabalho teve como objetivo estabelecer relacao entre a compreensao dos solos por parte dos Yanomami da regiao do medio Catrimani e o Sistema Brasileiro de Classificacao de Solos, bem como avaliar o seu tipo de uso em funcao de analises quimicas para diagnostico da fertilidade do solo. O trabalho foi executado em duas etapas. A primeira consistiu em visitas a oito malocas para estudar os solos. Foram coletadas amostras em trincheiras ate 1,50 m de profundidade para analise e classificacao dos solos e (em prospeccoes com o trado) nas profundidades de 0-10 a 10-30 cm, em 21 tipos de uso agricola, e da area de floresta para analises quimicas de fertilidade. A segunda fase foi uma oficina, abordando os sistemas de exploracao agricola, com duracao de 20 h. Focalizou-se a discussao sobre a compreensao do meio ambiente (Urihi)(1) e sistemas de producao agricolas e sobre a importância do uso correto do conhecimento dos solos. Os solos sao denominados pelos Yanomami em funcao das caracteristicas morfologicas, pelos teores de materia orgânica e pela presenca de minhocas, e da posicao na paisagem - a escolha para agricultura e fundamentada nessas caracteristicas. As praticas agricolas consistem da derrubada da mata nativa, queima e plantio das culturas em separado. Os solos descritos na area foram: Argissolo Vermelho-Amarelo (Maxita a uuxi wake axi), Argissolo Amarelo (Maxita a axi), Latossolo Amarelo (Maxita a axi) e Plintossolo (Maxita a axi a maamaxipe). O processo de derruba e queima promove um incremento inicial do teor de Ca e K trocaveis e P assimilavel devido a contribuicao das cinzas, o que permite a exploracao das areas por um periodo maximo de tres anos.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 with different types of agriculture and forests, both from profile soil (depth 0-1.50 m) and pits (depth 0-0.1 m and 0.1-0.3 m) for laboratory analysis. The second step was a workshop addressing the shift cultivation systems (duration 20 h). The discussion focused on the understanding of the environment (Urihi) and agricultural production systems, and on the importance of the correct use of knowledge of the soil and its fertility. Soils are named according to their morphology and position in the landscape by the Yanomami. The choice of agricultural areas is based on these features, aside from the organic matter content and the presence of earthworms. Agricultural practices comprise clearing and burning of the native forest immediately before planting a set of separate crops. The soils described in the area were classified according to the Brazilian taxonomic system as follows: Red Yellow Argisol (Maxita a uuxi wake axi), Yellow Argisol (Maxita a axi) Yellow Latosol (Maxita a axi) and Plintosol (Maxita a axi a maaxipe). Slashing and burning initially increases exchangeable Ca, K and available P due to the contribution of the ashes, which allows an agricultural exploitation of these areas for a maximum period of three years.

Efeito da aplicação de pó de basalto no desenvolvimento inicial de mudas de camu-camu (Myrciaria dubia)

The seedling production of native fruits is an important step towards the preservation of species, commercial exploitation and sustainable employment generation. In this context, alternative fertilizers, such as rock dust, provide obtaining a substrate with higher fertility, nutrient-rich, with reduced costs in manpower and replacement of fertilization. The objective in the present research was to evaluate the initial development of camu-camu seedlings (Myrciaria dubia H.B.K. McVaugh) in function of levels of crushed basalt. The experiment was carried out in a greenhouse, at CCA/UFRR. The experimental designed was completely randomized with eight treatments and five repetitions in factorial scheme (5x2+1), being five levels of crushed basalt (0, 0.42, 1.04, 2.08, 4.17 and 8.33 g kg-1), two particle size (0.05 mm and 0.10 mm f). Vases of polyethylene of 14L of capacity were the experimental units, and the soil was a Distrofic Yellow Latosol. The incubation period of the soil in vases was for 120 days and after that period the seedlings were transplanted to vases. Six months after the transplant the height, diameter of plant, branches number, and aerial part and root dry biomass of seedlings were determined. From this data the morphologic indexes were calculated. The Treatments without crushed basalt (0 g kg-1) and the levels 0.42 g kg-1 produced seedlings of lower quality in both granulometry analyzed. The better development of seedlings of camu-camu was obtained using 4.17 e 8.33 g kg-1 of crushed basalt with 0.05 granulometry.

Phytometal Availability, Evaluation of Antioxidant Activity and Total Phenolic Compounds of Genipa americana L. (Rubiaceae) Fruits

The present work studied the fruits of genipap ( Genipa americana L.) occurring in the city of Boa Vista, Roraima, State, Brazil. The content of the following minerals being evaluated: B, Ca, Cu, Fe, Mg, Mn, Na, P, Zn and their antioxidant activity on pulp, peel, seeds and oil extracted from the seeds. The levels of the minerals present in the different parts of the fruit were analyzed by flame atomic absorption spectroscopy (FAAS), flame atomic emission spectrometry (FAES) and UV-visible spectroscopy (UV/VIS). The mineral with the highest content was the potassium found in the peel (1,248.48±4.59 mg 100 g -1 ). The studies showed that the phenolic compounds are closely related to the antioxidant activity, in this study the peel presented the highest phenolic compounds content 712.21±11.04 mg GAE 100 g -1 and the pulp showed the highest capacity of Capture of the DPPH free radical of 661.34±17.12 EC 50 mg mL -1 , thus the genipap is a fruit with a potential food of the Roraima region.

Effects of Management Practices and Land Use on Biological and Enzymatic Attributes of an Agricultural Area

A series of anthropogenic approaches, including burning practices and soil disturbances as soil cover removal, plowing and harrowing were experimentally undertaken to mimic land conversion for agricultural production in northern Amazonia. These manipulations led to changes in soil biological and biochemical properties. To reduce knowledge gaps concerning land conversion in the Amazon, the study objective was to evaluate the influence of land use and management practices on the biological attributes and enzymatic activity of the soil in Tepequem, a settlement in north of the Amazon, Brazil. Tepequem was chosen for being highly representative in terms of land use and management patterns in the region. Microbial biomass carbon (MBC), soil basal respiration (SBR), metabolic quotient (qCO 2 ) and enzymatic activity were analyzed. Land use changes resulted in alterations to soil quality. The spontaneous plants found on degraded pasture ensured system diversification, protection and organic contribution, facilitating resumption of ecological balancing of the soil. Good soil quality in managed pasture was attributed to the maintenance of soil cover, provided by grasses, and the absence of soil rotation. Burning, soil disturbances and lack of cover negatively influenced the biological and enzymatic activity in sites that were preparation, deforested and burnt. Chemical attributes are significant factors influencing soil quality and health at subsistance plantation. MBC, qMIC and qCO 2 , acid phosphatase, Beta-glucosidase and urease were the most sensitive parameters of differentiation of sites in preparation from those of native vegetation and pastures.

WEED INCIDENCE AFTER SOYBEAN HARVEST IN NO-TILL AND CONVENTIONAL TILLAGE CROPROTATION SYSTEMS IN RORAIMA’S CERRADO

The goal of this study was to evaluate the occurrence of weeds after soybean harvest in rotational systems of no-till and conventional tillage in the savannah of Roraima, Brazil. Two simultaneous experiments were conducted in adjacent areas, the first one with no-till soil management system and the second one with the conventional system, with crop rotations for five agricultural years: pearlmillet (2007/2008), soybean (2008/2009), maize (2009/2010), cowpea with maize (2010/ 2011), soybean (2011/2012) and maize (2012/2013). The used experimental design was the randomized block one with 28 plots, sized 3 x 15 m (45 m2) distributed in 4 blocks. In May 2010, the combined sowing of cowpea and maize was performed, and later, during the same month of 2011 soybean was sown. Thirty days after harvesting, weeds were collected. The botanical classification of species was performed by classes, families, scientific and popular names, as well as comparisons with specialized bibliographies. The evaluated phyto-sociological parameters were: relative frequency (FRR), relative density (DRR), dominance (Do), importance value index (IVI), Sorensen’s similarity index (SI), numbers of individuals (ha-1) and dry mass (%). Among the 37 species found in both planting systems, 60% belonged to the Liliopsida class; Fabaceae and Malvaceae stood out. However, Poaceae, belonging to the Magnoliopsida class, had the highest number of species in both systems. Most weed species were common in both systems.