Carbono, serapilheira e fertilidade do solo em monocultivo e sistema silvipastoril
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Data
2025-06-26
Autores
Coelho, Marino Salgarello
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Universidade Federal do Espírito Santo
Resumo
Silvopastoral systems are an alternative for the recovery of degraded pastures. Therefore, the objective of this study was to evaluate the litterfall input and decomposition, the increase in nutrient levels, and the C and N stock in the soil in different models of monoculture and silvopastoral systems in the south of Espírito Santo. Cultivation systems were implemented in the municipality of Jerônimo Monteiro, ES, Brazil: pasture in monoculture, eucalyptus in monoculture, pasture and eucalyptus in a silvopastoral system, pasture, eucalyptus, and leucaena in a silvopastoral system, and pasture and araribá (Caesalpinia ferrea) in a silvopastoral system. Soil fertility, soil C and N stock, the contribution of trees to soil C formation, biological N fixation, and litterfall input using collectors and litterbags to evaluate the decomposition of forest species' leaves were analyzed over a one-year period. The pasture in monoculture and the pasture and araribá in a silvopastoral system treatments showed the highest soil nutrient levels, attributed to low absorption and above-ground biomass composition compared to the eucalyptus in monoculture, pasture and eucalyptus in a silvopastoral system, and pasture, eucalyptus, and leucaena in a silvopastoral system. Total organic carbon and total nitrogen contents tended to increase over the 36 months of analysis, while phosphorus, potassium, and sulfur showed a decrease in their soil content. The carbon and nitrogen stock in the soil did not show considerable increases at 36 months. Only the pasture in monoculture treatment showed a higher N stock considering the depth down to 40 cm. Although no differences were found in the C and N stock in the studied systems, there was a change in the soil surface (up to 5 cm) from a grass-derived C source to a tree-derived C source in the eucalyptus in monoculture and pasture and eucalyptus in a silvopastoral system treatments. For the nitrogen stock, the biological fixation by legumes did not promote an increase of this nutrient in the soil. There was no difference in the annual dry mass input from leaves, miscellaneous components, and the total. Each silvopastoral system presented a different input dynamic over time, related to the region's climatic conditions and management. The pasture and araribá in a silvopastoral system treatment correlated senescence with wet periods, the eucalyptus in monoculture treatment correlated with temperature, while the pasture and eucalyptus in a silvopastoral system and the pasture, eucalyptus, and leucaena in a silvopastoral system treatments correlated negatively with winds. The total content of contributed nutrients followed a pattern in descending order of quantity: Ca>K>Mg>P>S for leaves and K>Ca>Mg>P>S for miscellaneous components and the total. The decomposition of the araribá species was greater than that of the eucalyptus species, and the nutrient mineralization speed followed the descending order K>Mg>P>S>Ca for the eucalyptus species and K>P>Mg>Ca>S for the araribá species. The systems with eucalyptus tended to contribute a greater dry mass, which ensured a higher nutrient input compared to the system with araribá. The decomposition dynamics showed that the leaves of the araribá species have a higher decomposition rate and nutrient availability. The use of a silvopastoral system aids in nutrient cycling and in improving the sustainability of agricultural activity and the environmental quality of properties
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Palavras-chave
Fertilidade do solo , Ciclagem de nutrientes , Centrolobium tomentosum , Isótopos estáveis , Variáveis climáticas , Integração pecuária floresta , Soil fertility , Nutrient cycling , Centrolobium tomentosum , Stable isotopes , Climatic variables , Livestock-forest integration