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Biological nitrogen fixation in soybean is enhanced when seed is treated with cobalt (Co) and molybdenum (Mo) prior to planting. In this study, our objective was to verify if Co and Mo application during the reproductive phase of the crop increases seed Co and Mo concentration without adverse effects on seed quality. Two experiments were conducted. First, we investigated foliar and soil Co and Mo application under greenhouse conditions. Next, we validated the results obtained in the first study. The treatments for both experiments consisted of Co doses combined with Mo, and a control without Co and Mo application. The foliar application was more efficient in producing enriched Co and Mo seed; meanwhile, as Co doses increased so did Co and Mo concentrations in the seed. There were no adverse effects on nutrition, development, quality, and yield of parent plants and seed when these micronutrients were applied. The seed showed higher germination, vigor, and uniformity for the development of soybean seedlings. We concluded that the application of 20 g ha−1 Co and 800 g ha−1 Mo via foliar application at the reproductive stage of soybean increased germination rate and achieved the best growth and vigor index of enriched seed.

A presença de arsênio no lodo de esgoto pode limitar a utilização agrícola desse resíduo, pois esse elemento químico apresenta elevada periculosidade aos seres vivos, podendo entrar na cadeia alimentar e acumular-se ao longo dessa. Diante do exposto, a pesquisa teve como objetivo avaliar o potencial de fitoextração de As pelo capim elefante, cultivado em lodo de esgoto puro. Visando o desenvolvimento de uma tecnologia de baixa custo para retirada de As do lodo de esgoto. O experimento foi realizado em casa de vegetação do ICA/UFMG durante 150 dias, em delineamento blocos casualizados. Os tratamento corresponderam a 5 períodos do cultivo de P. purpureum em parcelas de lodo de esgoto (30; 60; 90; 120 e 150 dias a partir do plantio de estacas) e 2 testemunhas (parcelas de lodo não cultivado e plantio da gramínea em solo). O As foi detectado em concentrações de 0,41 e 0,37 mg kg-1 no lodo de esgoto e solo, respectivamente. O P. purpureum  foi capaz de absorver  e translocar quantidades consideráveis de As, média de 0,35  mg kg-1,  variando de acordo com os períodos de cultivo. No final do período experimental, houve decréscimo de 27,03% na concentração de As no lodo quando comparado aos valores iniciais.

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This study aimed to evaluate the total contents of As, Cu and Zn in the profile of a Haplic Cambisol cultivated with crambe and corn and fertilized with sanitary sewage sludge and to compare them with those obtained in other forms of fertilization, as well as the content of metals in the grain of these crops. Two experiments were carried out in the field, one with maize cultivation and another with crambe, both were delineated as randomized blocks with four treatments and six replicates, which were: without fertilization, fertilization with sewage sludge dewatered and dried in the sun, with dry sewage sludge and with mineral fertilizers. At the end of the experiments soil samples were collected at 15, 50, 100, 150 and 200 cm depth for analysis of the total contents of As, Cu and Zn, as well as the grain of the crops. No differences were observed among the treatments. The total contents of As, Cu and Zn in the soil in both experiments and in the corn grains are below the limits of prevention and the maximum limit in grains established by the Brazilian resolutions. In relation to depth, the metal contents in the samples collected from the soil submitted to the fertilization treatments were similar to those quantified in the plots that did not received fertilization, but there was accumulation of Cu and Zn in the upper layers of the soil that received fertilization.

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The cultivation of grasses in sewage sludge (SS) with aeration has the potential for stabilization of sludge organic matter in the production of organic fertilizer. Thus, the objective of this work was to evaluate the cultivation of Urochloa brizantha and Pennisetum purpureum under aerated system on the chemical and biological attributes of SS to obtain a matured organic fertilizer. The study was conducted in a randomized block design in a 2x2+2 factorial scheme with four replications. Factors consisted of cultivation of P. purpureum or U. brizantha in SS, with or without intermittent aeration. Control treatments were SS without cultivation, with or without aeration. Sewage sludge was collected in layers and the chemical and microbial attributes were evaluated. There was no significant difference between treatments for grass dry matter. The C/N ratio was not matched with organic fertilizer stabilization due to similar losses of C and N (~7%). However, microbial activity was reduced in the presence of plant cultivation demonstrating improvement in the properties of the organic fertilizer produced. Through uni-and multivariate analysis, organic fertilizer produced from SS aerated and cultivated with P. purpureum showed matured organic matter.