Abstract
Soil organic carbon (SOC) is one of the central issues in dealing with soil fertility as well as environmental and food safety. Due to the lack of relevant data sources and methodologies, analyzing SOC dynamics has been a challenge in Morocco. During the last two decades, process-based models have been adopted as alternative and powerful tools for modeling SOC dynamics; whereas, information and knowledge on the most sensitive model inputs under different climate, and soil conditions are still very limited. For this purpose, a sensitivity analysis was conducted in the present work, using the DeNitrification-DeComposition (DNDC) model based on the data collected at a semi-arid region (Merchouch station, Morocco). The objective is to identify the most influential factors affecting the DNDC-modeled SOC dynamics in a semi-arid region across different climatic and soil conditions. The results of sensitivity analysis highlighted air temperature as the main determinant of SOC. A decrease in air temperature of 4 °C results in an almost 161 kg C ha−1 yr−1 increase in C sequestration rate. Initial SOC was also confirmed to be one of the most sensitive parameters for SOC. There was a 96 kg C ha−1 yr−1 increase in C sequestration rate under low initial SOC (0.005 kg C ha−1). In the DNDC, air temperature in climatic factors and initial SOC in variable soil properties had the largest impacts on SOC accumulation in Merchouch station. We can conclude that the sensitivity analysis conducted in this study within the DNDC can contribute to provide a scientific evidence of uncertainties of the selected inputs variables who can lead to uncertainties on the SOC in the study site. The information in this paper can be helpful for scientists and policy makers, who are dealing with regions of similar environmental conditions as Merchouch Station, by identifying alternative scenarios of soil carbon sequestration.
Highlights
Soil organic carbon (SOC) plays an important role in determining soil fertility, soil structure, nutrient retention, susceptibility to land degradation, and water holding capacity, and sustains food production [1,2,3,4,5]
Eleven alternative soil conditions were considered to represent the range of pH, SOC and clay content commonly observed in the study site
The sensitivity analysis test indicated that the SOC was sensitive to initial SOC and clay content
Summary
Soil organic carbon (SOC) plays an important role in determining soil fertility, soil structure, nutrient retention, susceptibility to land degradation, and water holding capacity, and sustains food production [1,2,3,4,5]. The improvement of this major soil component is of high importance, especially for soils with intrinsically low levels of organic matter in their surface layers. Mediterranean agricultural areas have typically a lower SOC than temperate zones depending on seasonal dryness and particular climate features [16,17]
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