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Título: | Nitrogen transfer between high- and low-quality leaves on a nutrient-poor Oxisol determined by 15N enrichment |
Autor: | Schwendener, Carol Melanie Lehmann, Johannes Camargo, Plínio Barbosa de Luizâo, Regina Celi Costa Fernandes, Erick C.M. |
Palavras-chave: | Biodiversity Biomass Forestry Gas Emissions Nitrogen Nutrition Soils Microbial Biomass Mineralization Nitrogen Transfer Plants (botany) Decomposition Leaf Litter Mulch Soil Nitrogen Biodiversity Biomass Emission Forestry Leaves Nitrogen Soil Gliricidia Gliricidia Sepium Theobroma Theobroma Grandiflorum |
Data do documento: | 2005 |
Revista: | Soil Biology and Biochemistry |
É parte de: | Volume 37, Número 4, Pags. 787-794 |
Abstract: | It has been proposed that the C/N ratio, or quality, of litter or mulch mixtures affects N release. Although total N release from these mixtures and the effects on soil N are relatively well understood, a mechanistic understanding of the interactions between litter species with respect to their N release is still lacking. This study examines decomposition and N dynamics in mixtures of high-quality leguminous mulch, gliricidia [Gliricidia sepium (Jacq.) Kunth. ex Walp.] with a C/N ratio of 13, and low-quality cupuaçu [Theobroma grandiflorum (Wild. ex Spring) Schumann] litter with a C/N ratio of 42, which occur in combination in agroforestry systems. Ratios of 100:0, 80:20, 50:50, 20:80, 0:100 of fresh 15N-enriched gliricidia leaves and senescent cupuaçu leaves, totaling the same dry weight of 6.64 t ha-1, were applied to an Oxisol and sampled at 6, 14, 38, and 96 days after application. After more than 40% of the N in the gliricidia leaves had been released and the microbial biomass N reached its peak, a significant increase in available soil N occurred at day 14, which was more pronounced with greater amounts of gliricidia in the leaf mixture. However, relative to the N applied in the leaf mixture, there was no significant difference in available soil N with greater proportions of gliricidia. Total N release from the mixtures corresponded to the total N applied by gliricidia. Until day 38, cupuaçu C mineralization was significantly faster in the presence of the highest proportion of gliricidia compared to lower proportions. This faster C mineralization of more than 0.5% per day, however, did not increase total C loss or N release from cupuaçu leaves after 96 days. The use of 15N tracers identified an N transfer from gliricidia leaves and the soil to cupuaçu leaves and consequently, a lower N release from gliricidia to the soil in the presence of cupuaçu leaves. Though we expected that available N in the soil would also decrease with greater amounts of cupuaçu litter in the mixture, our results indicated an additive effect of the two species on N release and soil mineral N, with gross interactions between them canceling net interactive effects. Therefore, N release of leaf mixtures behaved as predicted from a calculated sum of individual release patterns, in spite of a transfer of N from the high- to the low-quality leaves. © 2004 Elsevier Ltd. All rights reserved. |
DOI: | 10.1016/j.soilbio.2004.10.011 |
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