SORPTION OF INDAZIFLAM IN BRAZILIAN SOILS WITH DIFFERENT pH VALUES

ABSTRACT Pre-emergence herbicides, such as indaziflam, have agronomic efficiency when available in the soil solution, mainly in the superficial layer (0-10 cm), the region with the highest concentration of weed seed bank. However, information about the sorption of indaziflam in Brazilian soils still is scarce, since most studies available in the literature were conducted in soils of temperate regions. The objective of this study was to estimate the sorption of indaziflam using high-performance liquid chromatography (HPLC) and bioassay in a Latossolo Vermelho-Amarelo (Oxisol) and in a Cambissolo (Inceptisol), at pH values of 5.1 and 6.1. In the biossay, Sorghum bicolor was used as an indicator plant. Quantitative indaziflam data were obtained by HPLC, and the sorption and desorption coefficients were determined in the soils using Freundlich isotherms. Increasing the pH of the two soils from 5.1 to 6.1 resulted in reductions of C50 and sorption coefficient values. Desorption, a parameter estimated only by HPLC, showed an inverse behavior to that of sorption, that is, the lowest desorption was observed in the condition of highest sorption. It is concluded that the increase in pH of the studied soils reduces indaziflam sorption, influencing the recommendations of this herbicide, from both the agronomic and the environmental points of view. When the goal is to verify the presence or absence of indaziflam in the studied soils, the bioassay technique has satisfactory efficiency. Chromatographic assay is necessary when quantifying the concentration of this herbicide in the soil.

Molybdenum and potassium in the foliar fertilization and seed quality in the soybean

Molybdenum is the micronutrient required in less quantity by plants and found in lower concentrations in Brazilian soils. The study aimed to study the influence of the application of molybdenum (Mo) and potassium (K) via foliar feeding, at different phenological stages, on the quality of soybean seeds. The work was conducted in the field in the county of Coronel Bicaco, RS under the condition of a typical dystropheric red Latosol (Oxisol) soil, in the 2017/2018 season crop. The experimental design was randomized blocks in a factorial scheme phenological stages x cultivars. Analysis of variance revealed significance for the interaction between phenological stages x cultivars for the variables composed by germination, abnormal, hard, dead, as well as field emergence, plant length and root length. There is influence of foliar feeding of molybdenum (Mo) and potassium (K) in different phenological stages of soybean. It was found that there was no significant difference for the yield of soybean cultivars under foliar feeding of Mo and K in the different treatments to which they were submitted.

Maghemite in Brazilian Iron Ores: Quantification of the Magnetite-Maghemite Isomorphic Series by Χ-ray Diffraction and the Rietveld Method, and Confirmation by Independent Methods

Maghemite (γ-Fe2O3) is a mineral formed from magnetite oxidation at low temperatures, an intermediate metastable term of the magnetite to hematite oxidation and could be mixed with both. It has magnetic susceptibility similar to magnetite, crystal structure close to magnetite with which it forms a solid solution, while compositionally it equals hematite. Maghemite is thus easily misidentified as magnetite by Χ-ray diffraction and/or as hematite by spot chemical analysis in iron ore characterization routines. Nonstoichiometric magnetite could be quantified in samples of Brazilian soils and iron ores by the Rietveld method using a constrained refinement of the Χ-ray patterns. The results were confirmed by reflected light microscopy and Raman spectroscopy, thus qualitatively validating the method. Χ-ray diffraction with the refinement of the isomorphic substitution of Fe2+ by Fe3+ along the magnetite-maghemite solid solution could help to suitably characterize maghemite in iron ores, allowing for the evaluation of its ultimate influence on mineral processing, as its effect on surface and breakage properties.

Urochloa brizantha cultivated in aluminum-toxic soil: Changes in plant growth and ultrastructure of root and leaf tissues

Brazilian soils destined for fodder production are infertile and acidic and contain toxic levels of aluminum (Al), which cause a reduction in growth of the root system and aerial plant parts. The main aim of the present pot trial was to determine ultrastructural and developmental changes in root and leaf tissues of Urochloa brizantha, when grown in an acid Oxisol containing varying levels of Al. The experimental design was a 3 × 5 factorial arrangement, involving 3 cultivars of U. brizantha (Marandu, Paiaguás and Piatã) and 5 concentrations of Al in the soil (0.2, 0.4, 0.8, 1.6 and 3.2 cmol/dm3), with 4 replications; a total of 60 pots. All cultivars responded negatively to increasing Al concentration in the soil, even in small amounts. Root ultrastructures were damaged even at concentrations of 0.4 cmol Al/dm3, primarily in the conducting tissues (xylem and phloem) and epidermal cells. Shoot development and leaf tissues were also negatively affected. In general, plant development and ultrastructure of root and leaf tissues in all 3 cultivars of U. brizantha were impaired when grown in the presence of Al at doses >0.2 cmol/dm3 in the soil.

Avaliações de Funções de Pedotransferência para Solos Brasileiros

Pedotransfer Functions (FPT) are mathematical models that estimate difficult-to-measure soil properties through more accessible variables, generating optimization of time and financial resources. In this study, six Pedotransfer Functions, based on the equation of Van Genuchten, analyzed for the prediction of volumetric moisture of Brazilian soils, with data from the global database Soil Data Task. Applied for pressures of 0, 0.01, 0.03, 0.10, 0.20, 0.50, 2.50 and 15.0 bar, the resulting values of the equations were compared with the measured volumetric moistures through five statistical parameters: confidence index, mean square error, deviation ratio, modeling efficiency and residual mass coefficient. Of the functions studied it was possible to verify that the FPT proposed by Barros, with 4 parameters, was the one that presented the best results, while that of Rawls and Brakensied obtained the lowest performance. It has been observed that the efficiency of a FPT is related to two factors: a) similarity between the pedological data of the soil studied and those used in the development of the FPT, and b) the amount of variables analyzed.

PRELIMINARY RADIOCARBON DATING RESULTS OF BONE SAMPLES AT THE LAC-UFF, BRAZIL

ABSTRACT Collagen extraction depends on the state of bone preservation, and the acidity of Brazilian soils often prevents the use of this material for radiocarbon dating. When available, however, bone samples constitute very important chronological records for both archaeological sites and natural depositional sites of specific animals. The extraction of collagen was performed using two filters, the first aiming to remove insoluble contaminants, and the second, a vivaspin ultrafilter 30KD to retain large molecular weight materials. The collagen was liofilized and converted to CO2 by combustion in sealed quartz tubes with CuO and Ag. The graphite was produced by zinc reduction in independently sealed Pyrex™ tubes. In order to verify the accuracy of this protocol, we analyzed a modern bone and four previously dated fragments, including those from the Sixth International Radiocarbon Intercomparison (SIRI), and a fragment of human bone from the Amourins site, a Brazilian shellmound. The results for the known age material are in agreement with the expected and the studied sector of Amourins shellmound was dated 4100–3900 years cal BP from a chronological model performed with charcoal dating found in different stratigraphic layers. Samples were dated at the radiocarbon laboratory of Universidade Federal Fluminense (LAC-UFF) in Brazil.

Effects of liming on the growth and nutrient concentrations of pitaya species in acidic soils

With the increasing demand for pitaya orchard management information to achieve high productivity and commercial quality fruits, liming practice is fundamental since most Brazilian soils are acidic. This study aims to assess lime requirements of Typic Quartzipisamment and Haplorthox soils to calculate tolerated aluminum saturation, desired base saturation, calcium and magnesium requirements to cultivate two pitaya species; Hylocereus undatus and Hylocereus polyrhizus. Two independent experiments were conducted in a greenhouse, organized in a 2 x 4 factorial scheme. Treatments were distributed in randomized blocks with five replications. Treatments of the first experiment corresponded to H. undatus and H. polyrhizus and four lime requirements, 0; 0.8; 1.2 and 1.7 t ha-1 cultivated in Typic Quartzipisamment. Treatments of the second experiment corresponded to H. undatus and H. polyrhizus and four lime requirements, 0; 1.3; 2.0 and 2.8 t ha-1 cultivated in Haplorthox. Shoot and root dry matter, chemical soil attributes and shoot nutrient concentrations were measured. Regression equations were adjusted for each variable, according to the lime requirements of both soils providing the highest dry matter yield in both pitaya species. H. undatus and H. polyrhizus cultivated in Typic Quartzipisamment produced more dry matter when the aluminum saturation was between 13% and 16%, base saturation 70% and the calcium and magnesium requirement 2.5 cmolcdm-3. H. undatus and H. polyrhizus cultivated in Haplorthox produced more dry matter when the aluminum saturation was between 1% and 4%, base saturation between 55% and 70%, and calcium and magnesium requirement 3.0 cmolcdm-3.