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.
THE IMPACT OF TREATMENT OF ORGANIC MANURES ON FUTURE SOIL CARBON SEQUESTRATION UNDER DIFFERENT TILLAGE SYSTEMS IN PAKISTAN
