Impacto do consórcio milho-braquiária no crescimento, características nutricionais e fisiológicas do milho e na atividade da microbiota do solo

• Autor(a) principal: Freitas, Marco Antonio Moreira de
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1217
• topic: Arranjo de plantas; Forrageira; Nicosulfuron; Sustentabilidade; Plant arrangement; Forage; Nicosulfuron; Sustainability; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The intercropping of maize with forage species is common practice to allow better land use and sustainability of the agricultural system. However, the competition between cultures that have similarities in photosynthetic processes, if not controlled properly, can derail economically this cultivation system. Thus, to succeed in the consortium corn signalgrass is necessary to ensure the initial competitive advantage of corn over natural resources, especially light. For this to occur should adjust the spacing between rows of trees to plant density and the initial rate of forage growth. This can be done with sublethal herbicide applications. This research evaluated the effects of row spacing of corn associated with seeding densities of Urochloa Brizantha with and without herbicide application to reduce the rate of growth of forage on growth, physiological characteristics, production, nutrient contents in plants corn. We also assessed the effects of these treatments on soil microbes by microbiological indicators, aiming to demonstrate the sustainability of this farming system activity. For this, two experiments were conducted in a randomized block design with four replications: one with corn grown in the spacing of 0.50 m and the other with 1.0 m between rows. Treatments were arranged in the same way in both experiments, in a 2x4 factorial design, with the first factor to the dose applied nicosulfuron ( 0 and 8 g ha - 1 ) and as second the forage seeding rates (0, 2, 4 and 6 kg of seeds per hectare). Microbiological soil properties were evaluated only in the experiment with 0.5 m spacing between rows of corn. For microbiological analyzes soil samples of rhizosphere soil were collected during flowering maize to determine the respiratory rate, the carbon associated with microbial biomass, metabolic quotient, the diversity and number of spores, total glomalin and glomalin extracted easily, and were also collected the finer roots of corn to determine the percentages of colonization by these hyphae. The accumulation of dry matter of shoots and leaf area were negatively altered corn when corn was grown at a spacing of 1.00 m, while the height of plants increased. Increasing the seeding rate brachiaria reduced by up to 15 % corn yield. However, this reduction was three times lower when applied to 1/5 the recommended dose of nicosulfuron (8 g ha- 1). The levels of foliar nitrogen on corn reverse responded to increased density of forage in the consortium. The increased density of forage maize grown in the spacing of 1.00 m between rows promoted the linear reduction of P and K, independent of the application of nicosulfuron. However, for the spacing of 0.50m this reduction was seen only in the absence of herbicide. Highest values for all variables related to production were observed with narrow row spacing and herbicide application. The highest density of seeding and herbicide application brachiaria interfered with microbiological indicators of soil. Narrow row spacing of corn combined application of suboptimal dose of nicosulfuron reduced the negative effects of the interference of U. Brizantha about nutrition and corn production.