Fertilizantes de leguminosas: tecnologia inovadora de adubação verde para provisão de nitrogênio em sistemas orgânicos de produção. / Legume fertilizers: innovative technology of green manuring for nitrogen supply in organic farming systems.
AUTOR(ES)
Maxwell Merçon Tezolin Barros Almeida
DATA DE PUBLICAÇÃO
2007
RESUMO
One of the main limitations to the organic food production is the reduced availability of low cost and efficient nitrogen (N) sources. Green manuring practices, in rotation or intercropped, have been used, but hardly are they able to supply crop needs. This dissertation presents an innovative technology of green manuring, derived of the cutting, dehydration and milling of the aerial biomass of some plants from Leguminosae family (with high potential of biological N2 fixation, N accumulation and handling easiness), with posterior storage and use of the produced material, called legume fertilizer. The technology allows the green manure storage, the production systematization and its use in more appropriate amounts and times, favoring the synchronization/efficiency of N provision. The objects of this study were: the development and evaluation of different production forms of legume fertilizers three herbaceous species: velvet bean (Mucuna pruriens), sunn hemp (Crotalaria juncea) and arachis (Arachis pintoi), and two species of tree: gliricidia (Gliricidia sepium) and leucaena (Leucaena leucocephala) ; the physical and chemical characterization of these materials, the utilization potential as alternative sources of N for organic farming systems, their influence on the shelf life of lettuce (Lactuca sativa cv. Vera), on chemical and biological soil attributes and on germination and establishment of arugula (Eruca sativa cv. Cultivada) seedlings. Three experiments have been conducted: one in field with lettuce, and two in green house with arugula. Legume fertilizers were compared at N basis with poultry bed manure from meat industry. The gliricidia fertilizer showed better physical and chemical attributes (lower C/N and lignin/N ratios) implying higher potential for biodisponibilization of N. This potential was corroborated for two experiments, in which the concentration and accumulation of N in the aerial part of lettuce and arugula was significantly superior to the other organic sources of N (velvet bean fertilizer and poultry bed manure). However, in the other experiment of arugula, the efficiency of five legume fertilizers and poultry bed manure were similar. The incorporation and the reduction of the applied doses of N had increased the efficiency of the provision of N for arugula. Antagonistic effect had been only observed on the germination and establishment of arugula seedlings when the legume fertilizers had been incorporated in the soil, but not when applied in surface. Lettuce shelf life was not affected by application of these organic sources of used N. The legume fertilizers and the poultry bed manure had favored the accumulation of C and total N, and the soil microbial activity with similar magnitudes. This dissertation indicates that legume fertilizers are promising sources of N for the organic farming systems, capable to replace the factory poultry bed manure at the same N level. This potential assumes relevance since poultry bed manure, one of the most used and efficient sources of organic of N, has some restrictions for its use in organic agriculture.
ASSUNTO(S)
fitotecnia fertilizantes nitrogenados. organic agriculture organic fertilizers nitrogenated fertilizers. agricultura orgânica fertilizantes orgânicos
