Challenges of soil carbon sequestration in the NENA region

Abstract

Abstract. The Near East North Africa (NENA) region spans over 14 % of the total surface of the Earth and hosts 10 % of its population. Soils of the NENA region are mostly highly vulnerable to degradation, and future food security will much depend on sustainable agricultural measures. Weather variability, drought and depleting vegetation are dominant causes of the decline in soil organic carbon (SOC). In this work the status of SOC was studied, using a land capability model and soil mapping. The land capability model showed that most NENA countries and territories (17 out of 20) suffer from low productive lands (> 80 %). Stocks of SOC were mapped (1:5 000 000) in topsoils (0–0.30 m) and subsoils (0.30–1 m). The maps showed that 69 % of soil resources are shown to have a stock of SOC below the threshold of 30 tons ha−1. The stocks varied between ≈10 tons ha−1 in shrublands and 60 tons ha−1 for evergreen forests. Highest stocks were found in forests, irrigated crops, mixed orchards and saline flooded vegetation. The stocks of soil inorganic carbon (SIC) were higher than those of SOC. In subsoils, the SIC ranged between 25 and 450 tons ha−1, against 20 to 45 tons ha−1 for SOC. Results highlight the contribution of the NENA region to global SOC stock in the topsoil (4.1 %). The paper also discusses agricultural practices that are favorable to carbon sequestration such as organic amendment, no till or minimum tillage, crop rotation and mulching and the constraints caused by geomorphological and climatic conditions. The effects of crop rotations on SOC are related to the amounts of above and belowground biomass produced and retained in the system. Some knowledge gaps exist, especially in aspects related to the impact of climate change and effect of irrigation on SOC, and on SIC at the level of the soil profile and soil landscape. Still, major constraints facing soil carbon sequestration are policy-relevant and socioeconomic in nature, rather than scientific.

Performance of wheat-based cropping systems and economic risk of low relative productivity assessment in a sub-dry Mediterranean environment

“…Without underestimating the role of plant genetics, the efficient management of water and N has been identified as a crucial need for closing the yield gap, which is estimated by comparing the observed yield with the attainable one (Mueller et al, 2012), of main cereal crops (Sinclair and Rufty, 2012) notably on arid and semi-arid soils with low organic carbon and nitrogen content (Darwish et al, 2018). Downscaling to field and farm levels made it possible to study and analyse the economic risk that farmers and producers could face, in relation to their adopted cropping systems (Di Falco and Perrings, 2005;Komarek et al, 2015;Mahmood et al, 2017;Valle et al, 2004).…”

A Review of Libyan Soil Databases for Use within an Ecosystem Services Framework

“…Soils in Libya have developed under arid conditions with limited soil organic carbon (SOC) and abundant soil inorganic carbon (SIC). A study [41] of soil carbon sequestration in the Near East North Africa (NENA) region found that 69% of the soils in the region had SOC stocks below 30 tons ha −1 . Soil types that were dominated by calcareous rocks (Solonchaks, Rendzinas, Yermosols) had the highest SIC content, while Lithosols and Xerosols had the lowest SIC content [41].…”

“…A study [41] of soil carbon sequestration in the Near East North Africa (NENA) region found that 69% of the soils in the region had SOC stocks below 30 tons ha −1 . Soil types that were dominated by calcareous rocks (Solonchaks, Rendzinas, Yermosols) had the highest SIC content, while Lithosols and Xerosols had the lowest SIC content [41]. In general, Libyan soils store significant amounts of SIC (Table 9, Figure 6).…”

On the use of validated ocean models to investigate the evolution of primary productivity in the Levantine Sea

“…Their importance lies in their ability to sustain all living organisms and to incorporate a broad range of ecosystem goods and services, including global biogeochemical cycling, food, and energy production, regulation of temperature, as well as providing a source of transport, recreation and job creation (Costanza 1999). Anthropogenic activities and land degradation are negatively affecting marine ecosystems (Darwish et al 2018;Ghoussein et al 2018). Continuous monitoring of these ecosystems has become a must to better understand and improve planning and decision-making, especially in regions with scarce data (Douvere and Ehler 2011;Fadel et al 2014).…”