Digital soil mapping using reference area and artificial neural networks.

Digital soil mapping is an alternative for the recognition of soil classes in areas where pedological surveys are not available. The main aim of this study was to obtain a digital soil map using artificial neural networks (ANN) and environmental variables that express soillandscape relationships. This study was carried out in an area of 11,072 ha located in the Barra Bonita municipality, state of São Paulo, Brazil. A soil survey was obtained from a reference area of approximately 500 ha located in the center of the area studied. With the mapping units identified together with the environmental variables elevation, slope, slope plan, slope profile, convergence index, geology and geomorphic surfaces, a supervised classification by ANN was implemented. The neural network simulator used was the Java NNS with the learning algorithm "back propagation." Reference points were collected for evaluating the performance of the digital map produced. The occurrence of soils in the landscape obtained in the reference area was observed in the following digital classification: medium-textured soils at the highest positions of the landscape, originating from sandstone, and clayey loam soils in the end thirds of the hillsides due to the greater presence of basalt. The variables elevation and slope were the most important factors for discriminating soil class through the ANN. An accuracy level of 82% between the reference points and the digital classification was observed. The methodology proposed allowed for a preliminary soil classification of an area not previously mapped using mapping units obtained in a reference area

Physical and chemical properties of starch and flour from different common bean (Phaseolus vulgaris L.) cultivar.

The physical, chemical and pasting properties of the flour and isolated starches from six different bean cultivars (Phaseolus vulgaris L.) were investigated in order to obtain information for application in new products. The protein and total starch contents of the bean flours ranged from 17.72 to 20.27% and from 39.68 to 43.78%, respectively. The bean starches had low amounts of proteins, lipids and ash and showed an amylose content ranging between 45.32 and 51.11% and absolute density values between 1.55 and 1.78 g.cm?3. The bean starch granules were round to oval with a smooth surface. Results viscoamylographic profiles of the starches and flours showed the possibility of selecting cultivars for specific applications according to these characteristics.

Organic and nitrogen fertilization of soil under Syrah grapevine: effects on soil chemical properties and nitrate concentration.

Viticulture is an activity of great social and economic importance in the lower-middle region of the São Francisco River valley in northeastern Brazil. In this region, the fertility of soils under vineyards is generally poor. To assess the effects of organic and nitrogen fertilization on chemical properties and nitrate concentrations in an Argissolo Vermelho-Amarelo (Typic Plinthustalf), a field experiment was carried out in Petrolina, Pernambuco, on Syrah grapevines. Treatments consisted of two rates of organic fertilizer (0 and 30 m3 ha-1) and five N rates (0, 10, 20, 40, and 80 kg ha-1), in a randomized block design arranged in split plots, with five replications. The organic fertilizer levels represented the main plots and the N levels, the subplots. The source of N was urea and the source of organic fertilizer was goat manure. Irrigation was applied through a drip system and N by fertigation. At the end of the third growing season, soil chemical properties were determined and nitrate concentration in the soil solution (extracted by porous cups) was determined. Organic fertilization increased organic matter, pH, EC, P, K, Ca, Mg, Mn, sum of bases, base saturation, and CEC, but decreased exchangeable Cu concentration in the soil by complexation of Cu in the organic matter. Organic fertilization raised the nitrate concentration in the 0.20-0.40 m soil layer, making it leachable. Nitrate concentration in the soil increased as N rates increased, up to more than 300 mg kg-1 in soil and nearly 800 mg L-1 in the soil solution, becoming prone to leaching losses.

Physico-chemical characterization of banana varieties resistant to black leaf streak disease for industrial purposes.

A cultura da banana tem baixa diversidade genética, tornando a espécie susceptível a doenças dizimadoras como a Sigatoka negra. No entanto, a adoção de novas variedades necessita de avaliações agronômicas e físico-químicas. Neste estudo, as variedades de banana, resistentes à Sigatoka negra, foram caracterizadas e comparadas com a variedade tradicional (Grand Naine). Cada variedade foi avaliada considerando-se critérios relevantes para a agroindústria, como pH, sólidos solúveis totais, acidez total titulável, relação SST/ATT, açúcares totais, açúcares redutores e não redutores, umidade, sólidos totais e rendimento no processamento. A variedade Thap Maeo apresentou-se como a variedade mais potencial para substituição da Gran Naine na indústria, com altos teores de sólidos solúveis totais, açúcares redutores, açúcares totais e umidade. As variedades Caipira e FHIA 2 também podem substituir a Grand Naine. Na análise de agrupamentos, verificou-se que a variedade Grand Naine esteve muito próxima das variedades do subgrupo Gros Michel (Bucaneiro, Ambroisa e Calipso) e também da variedade Caipira, apresentando no seu genoma o grupo AAA. Conclui-se que há opções de variedades resistentes para substituição da variedade tradicional, nas regiões afetadas pela Sigatoka-negra.

Mineralisation of the fungicide 14C-labelled metalaxyl fungicide in Brazilian soils.

Laboratory incubation experiments were carried out to estimate the mineralisation of metalaxyl 14C {N-(2-6 dimethyphenyl)-N-(methoxyacetyl) alanine methyl ester} in four Brazilian soils with different physico-chemical properties, at 3 and 30 ?g a.i. g-1. In the Petrolina sandy soil the mineralisation presented higher 14CO2 production rates, at two essayed concentrations, after 70 days. Microbiological studies were done to determine the numbers of bacteria, actinobacteria and fungi (CFU g-1 soil). In relation with other microbial community, bacterial population demonstrated to be a major component of the cultivable heterotrophic community after the application.of the compound. No detectable metabolites were found in this study. The results suggest that soil properties and application history may have a strong influence on the fungicide behavior in these soil samples.

Thermal tool for evaluation of essential oils of Eucalyptus spp susceptible and resistant to Glycaspis brimblecombei attack.

Eucalyptus spp genus is economically important to different industry fields. There are pests that damage the development of eucalypts and Glycaspis brimblecombei, a sap-sucking insect, is one of them. Studies about this insect attack to the eucalypts showed preferences. This work aim was to compare the preferences of the insect with thermoanalytical characteristics of different eucalypts (susceptible, less susceptible and resistant to Glycaspis brimblecombei) essential oils. The leaves of six species of Eucalyptus were crushed and the essential oil was extracted using Clevenger apparatus. The Shimadzu DTG-60H was used to analyze the samples. The results showed that the samples from more susceptible eucalypts had total mass loss at about 124ºC to 156ºC, lower than samples from more resistant eucalypts (from 168ºC to 175ºC). Furthermore, the study suggests that the susceptibility or the resistance of eucalypts to the pest may be related to their essential oil composition and concentration of monoterpenes and sesquiterpenes.