Use este identificador para citar ou linkar para este item: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/668177
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Campo DCValorIdioma
dc.contributor.authorSCHROTH, G.
dc.contributor.authorSALAZAR, E.
dc.contributor.authorSILVA JUNIOR, J. P. da
dc.contributor.authorSEIXAS, R.
dc.contributor.authorMACEDO, J. L. V. de
dc.date.accessioned2025-03-18T20:30:14Z-
dc.date.available2025-03-18T20:30:14Z-
dc.date.created1999-05-20
dc.date.issued1999
dc.identifier.citationIn: SHIFT PROJECT ENV 23 (Manaus-AM). Recuperacao de areas degradadas e abandonadas, atraves de sistemas de policultivo. Manaus: Embrapa Amazônia Ocidental, 1999.
dc.identifier.urihttp://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/668177-
dc.descriptionUnder rainforest vegetation, the Oxisols and Ultisols which dominate Amazonian uplands are characterized by relatively high availability of N in relation to other nutrients. When the rainforest vegetation is converted into agricultural systems, the disruption of the nutrient recycling mechanisms of the forest under conditions of intensive rainfalls and permeable soils increases the potencial for N leaching. In a previous study, substantial amounts of mineral N were found in the subsoil of central Amazonia Oxisol under various tree crops and a legumenous cover crops, indicating that even under perennial cropping systems, much of the mineralized soil and fertilizer N may be lost unproductively. We hypothesized that the spatial and temporal patterns of N availability and N mineralization in the soil of a polycultural system would influence the efficiency with which N is taken up by the trees instead of being leached. The analysis of such pattens coul lead to strategies for improving this efficiency and reducing the dependence of the system on external nutrient inputs. The concentration of mineral N and the net N mineralization in the topsoil were measured at five occasions during 10 months in a multi-strata agroforestry system on an Oxisol in central Amazonia, Brazil. The system was composed of three tree crop species and a leguminous cover crop, and was studied at two fertilization levels. The net N mineralization was highest under the cover crop, intermediate under a tree crop where the soil was also covered by the cover crop. This resulted in higher mineral N concentrations in the soil under the cover crop than under the tree crops during part of the rainy season. The increased N mineralization under the cover crop was due to higher total N in the soil, higher soil moisture and presumably a larger pool of readily mineralizable N components in the soil compared to the tree crops. Other fertility parameters also differed significantly between sampling positions within the plots, but this had no major influence on net N mineralization. Also, the fertilization level had no significant influence on N mineralization. As most of the N was mineralized under the cover crop at some distance from the trees, the uptake of the mineralized N by the tree crops could presumably be increased, and N leaching reduced, by a higher tree density and an altered management of the cover crop to increase N mineralization in the soil close to the trees. In view of the high total N mineralization rates in the system (349 kg ha-1 yr-1) and unclear yield responses of the tree crops to N fertilization at this site, it is concluded that after an establishment phase, the fertilization with N of tree crops with well-developed root systems may not always be necessary on this soil type.
dc.language.isoeng
dc.rightsopenAccess
dc.subjectAgrofloresta
dc.subjectBrasil
dc.subjectAmazonas
dc.subjectManaus
dc.titleSpatial and temporal patterns of N availability and N mineralization under tree crops and a cover crop in a multi-strata agroforestry system of central Amazonia.
dc.typeParte de livro
dc.subject.thesagroCultivo Multiplo
dc.subject.thesagroFertilidade do Solo
dc.subject.thesagroFloresta Tropical Úmida
dc.subject.thesagroNitrogênio
dc.subject.thesagroSolo
dc.subject.nalthesaurusagroforestry
dc.subject.nalthesaurusmultiple cropping
dc.subject.nalthesaurusnitrogen
dc.subject.nalthesaurusnitrogen fertilizers
dc.subject.nalthesaurussoil
dc.subject.nalthesaurussoil fertility
dc.subject.nalthesaurustropical rain forests
dc.description.notesRelatório Anual 1998.
dc.format.extent2p. 58-89.
riaa.ainfo.id668177
riaa.ainfo.lastupdate2025-03-18
dc.contributor.institutionJOSE PEREIRA DA SILVA JUNIOR, CPAA; JEFERSON LUIS VASCONCELOS DE MACEDO, CPAA.
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