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Cruz D.L.S.,Federal University of Roraima | Cruz P.L.S.,Federal University of Roraima | Cruz A.B.S.,UFRR | Nascimento P.P.R.R.,UFRR
Revista Brasileira de Ciencia do Solo | Year: 2014

The broad soil and ecosystem diversity of the state of Roraima is gradually being replaced by pasture and, depending on the management system adopted, this can be associated with soil physical degradation. Within this context, the aim of the present study was to evaluate and compare the soil physical attributes of an Argissolo Amarelo (Ultisol) under savanna and forest natural ecosystems, and their conversion into a cattle pasture system. The primary treatments were natural savanna (NS), savanna converted to pasture (CS), natural forest (NF) and forest converted to pasture (CF). The secondary treatments were the soil sampling depths of 0-10, 10-20 and 20-40 cm. The following physical properties were evaluated: texture, bulk density (SD) and particle density (PD), resistance to penetration (PR), total porosity (TP), gravimetric moisture (GM), available water capacity (AWC), and soil organic matter (SOM). The SD was greater in both savanna areas, without differences between CS and NS at any depth, associated with the cohesive character of savanna soils. The average PD value was typical of kaolinite soils. PR varied as a function of the areas and the depths; the effect of conversion on this property was observed. TP was greater in NF and less in CS, and TP decreased along with depth. AWC was greater in NF only at the 0-10 cm depth. SOM was greater in the NF and CF areas. The study concluded that conversion of the natural environment into pasture systems caused significant changes in PR, SD, AWC, TP and SOM, with major expressiveness in CF, due to the removal of natural vegetation, leading to the loss of SOM, which is an important conditioner of soil physical and water properties. In CS areas, suppression of the natural vegetation did not lead to the same expressiveness, mainly due to the significantly lower SOM contents.

Albuquerque J.A.A.,UFRR | Evangelista M.O.,UFRR | Mates A.P.K.,UFRR | Alves J.M.A.,UFRR | And 3 more authors.
Planta Daninha | Year: 2014

A phyto-sociological survey is the first step to implement integrated weed management in crops. In this study, weed occurrence was evaluated in cassava plantations in the savannah of Roraima in northern Brazil. Harvest was performed randomly 80 times in 10 crops over four seasons (January, February, March, and April 2012). The harvested plants were cut at ground level, sorted out per species, identified, quantified, and weighed on a 0.01 g precision scale. A descriptive analysis was conducted of the phyto-sociological parameters (frequency, density, abundance, total number of individuals per species, relative frequency, relative density, relative abundance and importance value index) for the collected species. A description was also made of the botanical classes, families, species, type of propagation, life cycle, growth habit, total number of species and dry weight ha-1. The community in the surveyed area was considered to have a heterogeneous composition, comprising 27 species. The species presenting the highest density per hectare were Digitaria sanguinalis (210,500), Brachiaria brizantha (111,000), Brachiaria decumbens (86,500) and Brachiaria humidicola (69,000). Digitaria sanguinalis had the highest relative density (28.08), relative abundance (26.16) and importance value index (65,34). Most weeds had herbaceous growth habit.

Albuquerque J.A.A.,Dep. de Fitotecnia | Melo V.F.,Dep. de Solos e Engineering Agricola | Siqueira R.H.S.,UFRR | Martins S.A.,UFRR | And 3 more authors.
Planta Daninha | Year: 2012

The aim of this work was to identify the occurrence of weeds after five years of notillage corn cultivation in the Amazonian savannah. A phytosociological survey was conducted involving collection, identification, and quantification of the weeds, after corn harvest during June and July, 2010. The investigated properties included botanical classes, families, species, number of individuals, frequency, density, abundance, relative frequency, relative density, relative abundance, importance value index, propagation method, and life cycle. The emergent vegetation in the study area had 419 species, nine of which were identified as Dicotyledons, while six were identified as Monocotyledons. Species in the Ciperaceae family were the most abundant, while the families Poaceae, Ciperaceae, Asteraceae, Malvaceae, and Fabaceae exhibited the highest number of individuals and species frequency per plot. Only the Cordia curassavica shrubby growth habit was identified. Cyperus rotundus species showed the highest values in all the phytosociological parameters evaluated, with an importance index value 1.5 times higher than that of Brachiaria humidicola which had the second highest value (40.49).

Native Indians (Macuxi, Ingarikó and Uapishana) in the Raposa-Serra do Sol Indian Reserve have been cultivating forest soils since the early XIX century, especially those derived from dolerite sills, scattered within the quartzitic dominated landscape. Representative soils developed from mafic rocks under Indian shifting cultivation in northeastern Roraima, were submitted to physical, chemical and mineralogical analyses to characterize their pedogenetic characteristics and infer on their status under native Indian shifting cultivation. The soil profiles were classified as: Orthic Ebanic Chernosol (USDA Mollisol), vertic Orthic Ebanic Chernosol (USDA Mollisol), Eutrophic Haplic Cambisol (USDA mollic Inceptisol) and Eutrophic Red Nitosol (USDA Red Alfisol), which occupy, respectively, lower slopes and less dissected terrains (Mollisols) and steeper slopes (Alfisols). The first two are eutrophic, and not typical of the Amazon region. Their mineralogies range from kaolinite/goethite rich upland, deeply weathered Nitosol, to 2:1 clay rich downslope Chernosols. The latter has primary minerals in the silt fraction and high CEC resulting in high fertility. The Nitosols reveal a process of severe topsoil loss, due to widespread sheet erosion from deforestation and shifting cultivation. Chemical analyses showed varied soil fertility, ranging from high levels in the Chernosols to a low level in the non-cultivated Nitosol. Phosphorus levels are limited in all soils, despite the high fertility. The Chernosols located in lowland, flat areas close to the valley floor are more suitable environments for the slash-and-burn native farming system. In the Chernosols and Cambisols, the clay activity below the value limit for this class indicates a current natural process of increasing leaching. The more weathered and eroded Nitosol showed low Fe-oxalate and Si-oxalate levels. Micronutrients such as total zinc and copper, decreased with depth and weathering. The Nitosols showed the highest phosphate adsorption levels (1.574 mg g- 1 of soil) which can be attributed to its clayey texture. Chernosols showed overall lower P adsorption values, increasing with depth. All soils under native Indian cultivation display signs of physical and chemical degradation due to shortened fallow under intense land use pressure in the Raposa-Serra do Sol Reserve. © 2009 Elsevier B.V. All rights reserved.

Melo V.F.,Federal University of Roraima | Francelino M.R.,Federal Rural University of Rio de Janeiro | Uchoa S.C.P.,POSAGRO UFRR | Salamene S.,Institute Floresta | dos Santos C.S.V.,UFRR
Revista Brasileira de Ciencia do Solo | Year: 2010

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 maaxipé). 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.

da Silva P.M.C.,UFRR CCA | Neves L.C.,UFRR CCA | Bastos V.J.,UFRR CCA | Lima C.G.B.,UFRR POSAGRO | And 2 more authors.
Scientia Horticulturae | Year: 2016

The fruits were harvested for six consecutive years during the rainy season from a population native to a savannah environment, and they were analyzed at intervals of seven days after anthesis (DAA). Chemical analyses were conducted (pH, total acidity, soluble solids, total and reducing sugars, total and soluble pectin, polygalacturonase enzyme (PG) and pectin methyl esterase (PE) enzymes, phenolic compounds, vitamin C and antioxidant activity by the oxygen radical absorbance capacity (ORAC) and α, α-diphenyl-β-picrylhydrazyl (DPPH) methods), respiratory activity was determined, and physical evaluations were performed (diameter and fruit and pulp fresh weight). The experiment was conducted in a completely randomized design (CRD) with a regression analysis and model fitting using the statistical F-test at a 5% significance level. The results showed climacteric behavior of the fruit as well as significant antioxidant activity related to the presence of phenolic compounds and vitamin C. The harvesting time, according to the evaluated parameters, was determined to be the interval between 28 and 35 DAA. © 2016 Elsevier B.V.

The experiment was carried out in Piracicaba, SP, in order to evaluate the effects of different carbon dioxide levels applied with irrigation water, associated or not to the mulch plastic, on yield of summer squash. The experimental design was in random blocks in split plot design, with the factor levels of CO2 in the plot and the mulch plastic in split-plot. The treatments constituted on the following levels: 0; 59; 148 and 247 kg ha-1 of CO2. The irrigation was scheduled daily based on a tank class A, using a drip irrigation system. The leaf area, the number of fruit and the yield were evaluated. The levels of CO2 and mulch plastic influenced the leaf area; consequently, it provided increment in the number of fruit and yield of summer squash. The best yield of 15, 433 kg ha-1was obtained by 58.6 kg ha-1 of CO2 with the plastic mulch.

Welter M.K.,Agronomia CCA UFRR | Melo V.F.,UFRR | Bruckner C.H.,Campus Universitario | de Goes H.T.P.,Brazilian National Council for Scientific and Technological Development | Chagas E.A.,Embrapa Roraima
Revista Brasileira de Fruticultura | Year: 2011

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 φ). 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.

Barros M.M.,UFRR | Araujo W.F.,DSEA UFRR | Neves L.T.B.C.,DFT UFRR | de Campos A.J.,UEG UnUCET | Tosin J.M.,Brazilian National Council for Scientific and Technological Development
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2012

The aim of this study was to evaluate the effect of different rates of nitrogen on production and quality of watermelon 'Crimson Sweet'. This research was conducted in the experimental area of the Federal University of Roraima, Boa Vista, from January to April 2010. The experimental design was in randomized blocks with 4 replications. The treatments consisted of 5 levels of nitrogen (50, 100, 150, 200 and 250 kg ha-1 N) applied as urea in a conventional manner. The results showed that the maximum commercial production was 40,428 kg ha-1 with 144.76 kg ha-1 N. Regarding the fruit quality, the pH was not affected by treatments, showing mean value of 5.34. The length/diameter ratio and bark thickness also were not influenced by the treatments, while the firmness, content of soluble solids (SS), titratable acidity (TA), content of sugars (reducing, non reducing and total), the ascorbic acid content and the ratio SS/TA were not influenced by N levels.

Vieira M.G.A.,University of Campinas | De Almeida Neto A.F.,University of Campinas | Carlos Da Silva M.G.,University of Campinas | Nobrega C.C.,UFRR | Melo Filho A.A.,UFRR
Brazilian Journal of Chemical Engineering | Year: 2012

Heavy metal removal by adsorption using rice husks as a bioadsorbent was evaluated as an alternative for wastewater treatment. Batch equilibrium experiments and kinetic sorption studies were performed using monocomponent solutions of Ni(II), Cd(II), Zn(II), Pb(II) and Cu(II) in surface samples of in natura (RH) and calcined rice husks (RHA). RHA showed higher potential for removing lead and copper. Experimental data for adsorption isotherms of lead and copper were adjusted by Langmuir, Freundlich and Dubinin-Radushkevick (D-R) models, being better represented by the Langmuir model. The calcination of RH increased its surface area, improving its adsorption properties. From a morphological analysis obtained by SEM and diffraction patterns (XRD), a longitudinal fibrous and amorphous structure was observed for RH. TGA results indicated a total mass loss of around 60% for RH and 24.5% for RHA.

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