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Sevilla, Spain

Munoz-Rojas M.,CSIC - Institute of Natural Resources and Agriculture Biology of Seville | Munoz-Rojas M.,MED Soil Research Group | Jordan A.,MED Soil Research Group | Zavala L.M.,MED Soil Research Group | And 4 more authors.
Solid Earth | Year: 2012

Soil C sequestration through changes in land use and management is one of the sustainable and long-term strategies to mitigate climate change. This research explores and quantifies the role of soil and land use as determinants of the ability of soils to store C along Mediterranean systems. Detailed studies of soil organic C (SOC) dynamics are necessary in order to identify factors determining fluctuations and intensity of changes. In this study, SOC contents from different soil and land use types have been investigated in Andalusia (Southern Spain). We have used soil information from different databases, as well as land use digital maps, climate databases and digital elevation models. The average SOC content for each soil control section (0-25, 25-50 and 50-75 cm) was determined and SOC stocks were calculated for each combination of soil and land use type, using soil and land cover maps. The total organic C stocks in soils of Andalusia is 415 Tg for the upper 75cm, with average values ranging from 15.9 Mg C ha-1 (Solonchaks under "arable land") to 107.6 Mg Cha-1 (Fluvisols from "wetlands"). Up to 55 % of SOC accumulates in the top 25 cm of soil (229.7 Tg). This research constitutes a preliminary assessment for modelling SOC stock under scenarios of land use and climate change. © Author(s) 2012. CC Attribution 3.0 License. Source

Zavala L.M.,MED Soil Research Group | Zavala L.M.,University of Seville | JordaN A.,MED Soil Research Group | JordaN A.,University of Seville | And 4 more authors.
Soil Science and Plant Nutrition | Year: 2010

Rock fragments are a key factor for determining erosion rates, particularly in arid and semiarid environments where vegetation cover is very low. However, the effect of rock fragments in non-cultivated bare soils is still not well understood. Currently, there is a need for quantitative information on the effects of rock fragments on hydrological soil processes, in order to improve soil erosion models. The main objective of the present research was to study the influence of rock fragment cover on run-off and interrill soil erosion under simulated rainfall in Mediterranean bare soils in south-western Spain. Thirty-six rainfall simulation experiments were carried out at an intensity of 26.8 mm h-1 over 60 min under three different classes of rock fragment cover (<50%, 50-60% and >60%). Ponding and run-off flow were delayed in soils with high rock fragment cover. In addition, sediment yield and soil erosion rates were higher in soils with a low rock fragment cover. The relationship between soil loss rate and rock fragment cover was described by an exponential function. After this first set of experiments, rock fragments were removed from sites with the highest cover (>60%) and the rainfall simulation experiments were repeated. The steady-state run-off rate and soil loss increased significantly, showing that run-off and soil erosion were partly conditioned by rock fragment cover. These results have significant implications for erosion modelling and soil conservation practices in areas with the same climate and soil characteristics. © 2010 Japanese Society of Soil Science and Plant Nutrition. Source

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