Soil erosion, dissolved organic carbon and nutrient losses under different land use systems in a small catchment in northern Vietnam.

摘要

The export of dissolved organic carbon (DOC) from agricultural soils can represent an important pathway of soil organic carbon loss. However, despite its importance in terrestrial and downstream aquatic ecosystems, most work has focused on temperate agrosystems with tropical and sub-tropical ecosystems being ignored. Here we present the results of a series of rain simulation experiments aimed at examining DOC export from sloping lands in North Vietnam. Three regularly used agricultural practices were tested and compared with Bare soils. We also compared the impact of leaf litter in two planted forest sites. We found high rates of DOC export (0.03-0.25 g C m -2) during a 40 min rain episode with the lowest rates observed in the Bare soils and the highest in the planted Forest without leaf litter. This is equivalent to a loss of between 0.001 and 0.008% of the total soil organic carbon in the upper 10 cm during a single, intense rain event. This work highlights the impact of different agricultural practices (Bare soil, hoeing, mulching and fallow) and land use (planted Forest with or without leaf litter) on the export of DOC from upland, tropical soils and further underlines the importance of studying DOC fluxes from agricultural land as it represents an important and highly mobile component of ecosystem carbon fluxes.