946 resultados para Reciclagem de nutrientes


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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Pós-graduação em Agronomia (Horticultura) - FCA

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Pós-graduação em Agronomia (Horticultura) - FCA

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Pós-graduação em Engenharia Mecânica - FEIS

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In tropical regions there is rapid decomposition of plant material deposited on the soil, and the ability to recycle nutrients through this decomposition is one of the most important aspects of cover crops. The aim of this study was to evaluate the yield and nutrient release from forage crops intercropped with maize for silage, and soybean in succession. The study was conducted in the experimental area of Universidade Estadual Paulista, Ilha Solteira campus, Brazil. The experiment consisted of maize for silage intercropped with four forage species (Urochloa brizantha cv. Marandu, Urochloa ruziziensis, Panicum maximum cv. Tanzania, and Panicum maximum cv. Aries) sown in three modalities: in the maize row, together with fertilizer; broadcast at maize sowing; and broadcast in the V4 stage of maize, in a randomized block design in a 4 x 3 factorial arrangement with four replications. The evaluation of nutrient release was performed during the soybean cropping that followed the intercropping by the litter bag method at 30, 60, 90, and 120 days after sowing of soybean. Panicum maximum cv. Tanzania showed higher dry matter yield when sown by broadcasting at maize sowing. Sowing of forages in the maize row, and through broadcasting at maize sowing led to greater dry matter yield for straw formation. Intercropping of maize with forages in the autumn is an alternative for increasing the amount of straw and cycling of macronutrients in a no-till system. Potassium was the nutrient with the greatest accumulation in the forage straws (up to 150 kg ha(-1)), with 100 % release at 90 days after sowing soybean. The forage straws are thus an excellent alternative for cycling of this nutrient. Panicum maximum cv. Tanzania sown by broadcasting at the time of maize sowing showed greater phosphorus cycling (13 kg ha(-1)). Panicum maximum cv. Tanzania broadcast in the V4 stage of maize is the option with least potential for straw production and nutrient cycling, while the other options (forages and sowing modalities) have higher potential for use, at the criteria of machine availability for setting up intercropping with corn.

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Understanding the influence of vinasse application on trash decomposition and its effects on soil chemical attributes and sugar cane culture is essential for the good management of the production system. The objective of this study was to assess the time of decomposition and nutrient cycling of the green ratoon cane's trash, and their effects on soil fertility and technological components of crops, in terms of vinasse doses. The study was developed in the northwest region of Sao Paulo State - Brazil, under Eutrophic Ultisol, using the RB855453 variety. The experimental design was randomized blocks with split plot in time. The treatments were composed of four doses of vinasse (0, 50, 100 and 200 m(3) ha(-1)). There was a 20.9% reduction in the amount of crop residue remaining after one year review. The vinasse doses increased the ratoon cane's yield, without interfering in the raw material quality. The green cane system, in which the trash is deposited on the soil and vinasse application, changes the dynamics of the trash decomposition and modifies the soil fertility, contributing positively to the crop yield.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The production systems on substrates have been employed in most commercial cultivation of flowers and ornamental plants, including gerbera. However, its introduction as potted flower is recent in Brazil and many studies, especially those related to the determination of substrates physical and chemical properties, which contribute to production quality are still needed. The present study aimed to assess the influence of substrates characteristics for nutrient absorption and production of potted gerbera. The experiment was carried out in greenhouse with the experimental design in randomized blocks, factorial arrangement 5x2 (5 substrates and 2 cultivars) and 4 replications. Treatments consisted of substrates with different physical and chemical characteristics and gerbera cultivars (Cherry and Red). Plants grown on substrate with pH above 7.0 had a reduction in iron absorption, resulting in lower intensity of green coloration in the leaves. Plants grown on substrate with pH below 5.0 showed toxic levels of manganese and lower dry mass. The characteristics of the substrate, especially the pH, influence the nutrients absorption and the production of potted gerbera, altering the final plant quality.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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A energia eólica é uma forma de energia que seu uso encontra-se em expansão, e junto a esse crescimento, tem-se também o aumento da quantidade de resíduos gerados na fabricação das pás eólicas. Uma forma correta de destinação e aproveitamento desses resíduos é a reciclagem. Porém, esses são constituídos de materiais compósitos, geralmente a resina epóxi e a fibra de vidro; e por possuírem um polímero termofixo (a resina epóxi) na sua composição, a reciclagem convencional via fusão não é possível. Desta forma, a reciclagem química via pirólise apresenta-se como uma alternativa para o aproveitamento desses resíduos, em especial da fibra de vidro que o contém. Após caracterização do resíduo de uma indústria de pás eólicas, verificou-se que se tratava de um material com mais de 70% de fibra de vidro e muito densas. Foram realizados ensaios de pirólise a seco e com óleo de babaçu, considerado o mais interessante perante vários possíveis e no qual o resíduo fica totalmente imerso, facilitando o inchamento e a troca de calor. Em um sistema de aquecimento com vácuo, foram obtidas mais de 97% de fibras em 30 minutos a 310 oC, justamente a temperatura em que uma análise termogravimétrica apontou ser a de início de altas taxas de degradação térmica.

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The question related to recyclable material has been pointed by environmental researchers as one of the most serious urban problems today. Therefore, the importance of disclosure and clarification related to recycling techniques is highlighted, as well as a critical and extensive reflection related to the cultural values of society about current economic rationality that prioritizes a unlimited consumerism. We conducted a survey in the city of Bauru and asked how often people separated recyclable materials for selective collection. We found that 18% of these people have never performed this type of activity. Thus we emphasize the importance of art in creating alternative ways of dealing with the recyclable material, that involves social, economic and cultural needs of a population; contributing to preserve the environment such as the creation of a new rationality.