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Navegando EA - Artigos publicados em periódicos por Autor "Aguiar, Renata Alves de"
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Item Análise econômica de diferentes práticas culturais na cultura do milho (zea mays l.)(Alexsander Seleguini, 2008-12-30) Aguiar, Renata Alves de; Silveira, Pedro Marques da; Moreira, José Aloísio Alves; Wander, Alcido ElenorThe aim of this study was to economically assess different crop management practices for corn cultivation, involving soil management with the utilization of cover crops, hybrid breeds and nitrogen levels in topdressing, to estimate the benefit-costratio (BCR) of different practices. The corn experiment was planted at the beginning of February, in the Embrapa Arroz e Feijão research station, on a Distrophic Red Latosol. The experimental design was completely randomized blocks, with three replications and sub-subdivided plots. The plots were formed by four types of soil management: direct planting of corn on black mucuna stubble; on crotalaria stubble; and on spontaneous vegetation (fallow), and planting of corn in the conventional tillage system. The subplots were formed by five levels of nitrogen in topdressing (0 kg ha-1, 45 kg ha-1, 90 kg ha-1, 180 kg ha-1, and 360 kg ha-1) and the sub-subplots by four corn hybrids (BRS 3003, AG 1051, Green Maize HT-1, and Green Maize HT-2). The benefit-cost-analysis was performed on the basis of prices of inputs and operations collected on April 2007, using an Excel sheet. The practices with a BCR of more than 1.0 were considered economically viable. Considering BCR, the best soil management option was the fallow, without any addition of nitrogen in topdressing, followed by the system of conventional tillage, with 45 kg ha-1 of nitrogen in topdressing.Item Decomposição da biomassa e liberação de nutrientes dos capins braquiária e mombaça, em condições de cerrado(Alexsander Seleguini, 2010-09) Bernardes, Tatiely Gomes; Silveira, Pedro Marques da; Mesquita, Marcos Antônio Machado; Aguiar, Renata Alves de; Mesquita, Glaucia MachadoThe objective of this research was to evaluate the accumulation and release of nutrients from the dry biomass of brachiaria (Brachiaria brizantha) and guinea grass (Panicum maximum) used as cover crops in a no-tillage system, under Brazilian savannah conditions. The experiment was carried out at Embrapa Arroz e Feijão (Fazenda Capivara), in Santo Antônio de Goiás, Goiás State, Brazil, in a dystrophic Red Oxisol. A randomized block design, with four repetitions, in a split plot scheme in time, was adopted. At the flowering stage, plants were cut and kept on the soil, and the productivity of dry biomass, and nutrient accumulation, decomposition and liberation were evaluated at 0, 15, 30, 45, 60, and 75 days. The biomass yield was 16,643 kg ha-1, for brachiaria, and 18,244 kg ha-1, for guinea grass. For both cover crops, N was the most accumulated nutrient. Among the macronutrients, K showed the highest release rate (70% and 59%, respectively for guinea grass and brachiaria).Item Sustentabilidade de sistemas orgânicos com plantas de cobertura na cultura do arroz,por meio de alterações físicas do solo(Evandro Novaes, 2010-06) Aguiar, Renata Alves de; Moreira, José Aloísio Alves; Stone, Luís Fernando; Bernardes, Tatiely Gomes; Jesus, Roberta Paula deTo evaluate the influence of cover crops on Oxisol physical attributes, in an organic production system with conventional tillage, a study was conducted at Embrapa Arroz e Feijão, Santo Antônio de Goiás, Goiás State, Brazil, for two years, in a succession cover crops-rice, in which cover crops were sown in the autumn/winter and the subsequent crop, rice cultivar Aimoré, was sown in the summer. Five cover crops were used: Velvet bean (Mucuna aterrima), Sunn hemp (Crotalaria juncea), Pigeon pea (Cajanus cajan), Broom sorghum (Sorghum technicum), and spontaneous vegetation fallowing. A randomized blocks design with four replications was used. In the second year of experimentation (2005), soil samples were collected from plots and from a close forest, at depths of 0.00-0.10 m, 0.10-0.20 m, and 0.20-0.30 m, to determine organic matter content (SOC), soil physical properties, S index, and soil aggregation. The cover crops management was carried out at the flowering stage and its biomass incorporated into soil profile. For total porosity, microporosity and bulk density, there were no significant differences among depths, for different cover crops. For S index, for all treatments at the 0.00-0.10 m layer depth, values between 0.020 and 0.035, characterizing intermediate soil physical quality, were found. The percentage of aggregates with a diameter larger than 2 mm and the weighted average diameter of aggregates were higher at the 0.10-0.20 m layer depth. SOC decreased with depth, independently of cover crops.