Import?ncia da arboriza??o de pastagens com leguminosas fixadoras de Nitrog?nio

• Autor(a) principal: Dias, Paulo Francisco
• Data de Publicação: 2005
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRRJ
• Texto Completo: https://tede.ufrrj.br/jspui/handle/jspui/3946
• topic: Agrofloresta; Ciclagem de nutrientes; Fauna de solo; Sustentabilidade de pastagens; Nutri??o de pastagem; Agroforestry; Nutrient cycling; soil fauna; pasture sustainability; pasture nutrition; Agronomia

The leguminous trees can be a viable alternative in the recovery of degraded pastures areas, as suppliers of nitrogen and other functions which lessen the impacts of the activity on the environment. Currently, there is a very strong link to environmental management for this activity, the ecological and economic potential of the areas in study are the principal determining factors for their distribution and level of adoption. This being the case, the work had as general objectives: to select species of leguminous trees for planting in pastures; to evaluate the introduction of leguminous trees in pastures without protection of the transplants; to evaluate the contribution of nitrogen-fixing leguminous trees to the yield, quality of grass, on the characteristics of communities of soil macrofauna and, availability of alternatives for the adoption of the practice of tree planting in pastures. In order to conduct these studies, field experiments were set up in pastures of Brachiaria brizantha cv Marandu and Cynodon sp. Tifton 85, located in the Integrated System of Agroecology Production (ISAP ? Organic farm), Dairy Cow Area of PESAGRO/EES and rural producers located next to the Funil/FURNAS dam ? Itatiaia, RJ. Transplants of the species utilized in the experiments were prepared in the Experimental Field nursery of Embrapa Agrobiology, located in Seropedica, RJ and in the cities where the experiments were conducted. The group made up of the leguminous trees M. artemisiana, A. holosericea, M. tenuiflora, P. guachapele, A. auriculiformis, M. caesalpiniifolia and E. contortisiliquum showed potential for being introduced in pastures of the forage grasses Braqui?ria and Tifton 85, without having the need for protection of the transplants. The introduction of trees in pastures shows great potential for providing and maintaining the nutritional quality of forage under the conditions that were studied. Shade had a positive effect on the production of dry mass and nutrient content of the Survenola grass (Digitaria setivalva X Digitaria valida). According to tree heights and the chosen tree species, the distance of 2 times the projection of the canopy was not influenced by the tree. The transfer of N from the tree species is between 0 and 30%, being the greatest in the area of the projection of the canopy, and practically null at 2 times the projection of the canopy. The species E. contortisiliquum proved to be promising in improving soil fertility, and simultaneously providing a better nutritional quality of forage in the area of influence of its canopy and greater quantities of N, P, K, Ca and Mg produced per m2. The presence of legumes, whether or not they fix N2, contributes to the increase in richness of certain groups of soil fauna, principally (Oligochaetas, Coleoptera, Aranae and Formicidae). For the legume P. dubium, which showed the least amount development, not be a N2-fixing species provided favourable conditions for the dominance of the formicidae group in relation to the other two ecosystems with nitrogen-fixing legumes, as observed in the pasture outside of the influences of the canopy of the trees.