ABSTRACT The application of chemical substances to the soil together with little attention given to the possible environmental impacts, transformed the environment into a recipient of waste. The aim ...of this study was to simulate the movement of water and solutes (sodium and potassium together) using the STANMOD and HYDRUS-2D models in a typical Haplic Planosol under the application of wastewater via surface irrigation under different flow rates. The experiment was conducted in the laboratory by miscible displacement tests, first using columns with deformed soil under saturation and steady water flow conditions, at a rate of 11.7 cm3 min-1, to obtain transport parameters of sodium and potassium ions, and in the applied residual water, the values of 475 and 76.6 mg dm-3, respectively. The transport parameters were estimated from the numerical adjustment of effluent distribution curves, using the STANMOD model. In a second step, the HYDRUS-2D model was applied to simulate the volumetric soil moisture distribution profiles, as well as the ion concentrations in the wet bulb. Considering the results obtained, we can see that there was considerable interaction between the solutes and the soil. The value of the delay parameter was higher for the sodium when compared to the potassium, reflecting its greater adsorption and the processes of exchange between the solute and the soil. The results suggested the need for adequate soil management in order to avoid future soil sodification and, in view of the application of HYDRUS-2D, it was verified that the model presented a satisfactory performance in the simulation of the displacement of the ions, after 1, 5 and 10 hours of wastewater application.
ABSTRACT Maize crop under rainfed conditions is widely grown in the Brazilian Northeast on community farms for human and animal consumption. The application of mulch could be adopted to enhance ...rainwater harvesting and soil moisture levels, although such practice is rarely applied in rainfed cultivation. This study aimed to evaluate the spatial variability of maize productivity, based on soil physical attributes and plant growth and yield, under a rainfed regime in the presence and absence of mulch in the Brazilian semi-arid region. The study was conducted from May to September 2016 in Pesqueira - PE (locality of the Semiarid of Pernambuco State, Northeast, Brazil), during which the development and production of maize in experimental plots were evaluated, and maize was grown using the traditional cropping system with and without mulching. Two grids with 40 points in a 4 × 10 m mesh were established, with spacing of 1 m for soil sampling and maize biometric evaluation. For statistical analysis, 30 samples were randomly selected from each plot. Maize cultivated in the presence of mulch showed higher development, with symmetrical distribution for all variables except for soil moisture and stem diameter. Sand content, soil moisture, height of the first cob, number of leaves, leaf length, plant height, and cob weight presented moderate to strong spatial scale dependence for the two cropping conditions, with higher spatial dependence consistently observed for the development parameters in the covered area.
RESUMO O cultivo de milho em sequeiro é amplamente explorado no Nordeste Brasileiro pela agricultura familiar, para alimentação humana e animal. Para melhorar a captação da água da chuva e a umidade do solo, pode-se adotar a cobertura morta, embora essa prática ainda seja raramente aplicada no cultivo de milho de sequeiro. Neste contexto, o objetivo deste estudo foi avaliar a variabilidade espacial da produtividade do milho, com base nos atributos físicos do solo e no crescimento e produção da planta, sob regime de sequeiro na presença e na ausência de cobertura morta na região semiárida. O estudo foi realizado de maio a setembro de 2016 em Pesqueira-PE, avaliando o desenvolvimento e a produção de milho em parcelas experimentais, adotando-se o sistema tradicional sem cobertura morta e com cobertura. Estabeleceu-se dois grids com 40 pontos em malha de 4 x 10 m, com espaçamento de 1 m para amostragem de solo e avaliação biométrica. Para análise estatística, foram sorteadas trinta amostras aleatoriamente em cada parcela. O milho cultivado na presença de cobertura apresentou maior desenvolvimento, com distribuição simétrica para todas as variáveis, exceto para a umidade do solo e o diâmetro do colmo. O teor de areia, a umidade do solo, a altura da primeira bifurcação, o número de folhas, o comprimento da folha, a altura da planta e o peso da espiga apresentaram de moderada a forte dependência espacial para as duas condições, com maior dependência espacial sempre observada para os parâmetros de desenvolvimento na área com cobertura morta.
ABSTRACT Combining refrigeration with packaging is a commonly used technique for fruits intended for export. Thus, the objective of this study was to adapt the post-harvest management of biofortified ...sweet potato cultivars, using packaging and refrigeration, focused on reaching distant export markets while maintaining the commercial quality. Sweet potatoes of the cultivars BRS-Amélia and Beauregard were selected after harvesting, washed, and packaged. The experimental design used was completely randomized, in a 4 × 7 factorial arrangement consisted of 4 treatments (cultivar BRS-Amélia with and without packaging; and cultivar Beauregard with and without packaging) and 7 evaluations under storage conditions: at 0, 7, 14 (under refrigeration at approximately 8 °C), 17, 20, 23, and 26 days (under room temperature conditions at approximately 25 °C). Each experimental unit contained 500 g of tubbers. The results showed that the refrigerated storage combined with packaging extended the shelf life of the evaluated sweet potatoes: 17 days for BRS-Amélia and 26 days for the cultivar Beauregard. The BRS-Amélia cultivar maintained higher firmness, soluble solids and carbohydrate contents, chroma, and antioxidant activity (FRAP method), and total phenolic contents, in both raw and cooked tissues. The cultivar Beauregard presented less dehydration and greater stability in vitamin C, total phenolic, total carotenoid, soluble carbohydrate, and starch contents in raw and cooked potatoes. Therefore, the combination of packaging and refrigeration preserved the commercial quality of biofortified sweet potatoes for export markets.
RESUMO Combinar refrigeração com embalagem é uma técnica comumente utilizada para frutas destinadas à exportação. Assim, o objetivo deste estudo foi adequar o manejo pós-colheita de cultivares de batata-doce biofortificadas, utilizando embalagem e refrigeração, com foco em atingir mercados de exportação distantes e mantendo a qualidade comercial. As batatas-doces das cultivares BRS-Amélia e Beauregard foram selecionadas após a colheita, lavadas e embaladas. O delineamento experimental utilizado foi inteiramente casualizado, em arranjo fatorial 4 × 7 composto por 4 tratamentos (cultivar BRS-Amélia com e sem embalagem; e cultivar Beauregard com e sem embalagem) e 7 avaliações nas condições de armazenamento: aos 0, 7, 14 (sob refrigeração a aproximadamente 8 °C), 17, 20, 23 e 26 dias (sob condições de temperatura ambiente a aproximadamente 25 °C). Cada unidade experimental continha 500 g de tubérculos. Os resultados mostraram que o armazenamento refrigerado aliado à embalagem prolongou a vida útil da batata-doce avaliada: 17 dias para BRS-Amélia e 26 dias para a cultivar Beauregard. A cultivar BRS-Amélia manteve maior firmeza, solúveis sólidos e teor de carboidratos, croma e atividade antioxidante (método FRAP) e teor de fenólicos totais, tanto nos tecidos crus quanto cozidos. A cultivar Beauregard apresentou menor desidratação e maior estabilidade nos teores de vitamina C, fenólicos totais, carotenóides totais, carboidratos solúveis e amido em batatas cruas e cozidas. Portanto, a combinação de embalagem e refrigeração preservou a qualidade comercial da batata-doce biofortificada para os mercados de exportação.
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