World’s Soil Resources

3 - Sustainable land management mapping.
In each unit of the national map, the prevailing land management practices were inventoried using a
standard methodology (Liniger et al., 2011). This allowed the characterization of practices in terms of type of
intervention (agronomic, vegetative etc) and in terms of objectives (prevention, mitigation or rehabilitation).
At the same time, the extent, trend and efficiency of the conservation practices were assessed. Examples of
outputs are given for the main conservation types used in the country (Figure 13.8.) and for the impact of soil
degradation on ecosystem goods and services (Figure 13.9.).
13.6 | Conclusions
Although there is a wealth of local and national studies on soil change in the region, a systematic and
standardized approach is lacking. Results on the extent and intensity of soil change processes still refer to the
GLASOD study carried out in the late 1980s.
The degradation of natural resources in arable lands is considered as one of the main threats to agricultural
production in all countries of the region. Ecosystem service quality and capacity is greatly reduced by degradation
caused by salinity, erosion, contamination and poor management that leads to a loss of soil organic matter.
Water erosion is predominant in that part of the region which has sloping lands. Where rainfed agriculture
is practiced, water erosion may even occur in gently sloping areas. Wind erosion is also a causative factor of
topsoil removal. Population increase has resulted in soil disturbance due to uncontrolled human activities
such as mining and open quarries that have triggered and accelerated erosion processes. Degradation due to
salinity and sodicity varies geographically with climate, agricultural activities, irrigation methods and land
management policies and is mainly restricted to irrigated farming systems. Causative factors are of intrinsic
origin, seawater intrusion or irrigation from groundwater with elevated salt content. Degradation due to
contamination is mainly found in countries with high population, high oil production or heavy mining. In
irrigated farming systems with overuse of chemicals, the load of toxic elements in groundwater is increased.
Salinity has greatly reduced crop yields and increased economic annual losses across the region to nearly
US$1 billion, equivalent to as much as US$1 604 ha -1 to US$2 748 ha -1 . In some countries the reduction in soil
productivity was estimated to be in the range of 30-35 percent of the potential productivity.
Responses to degradation caused by erosion include improving soil resilience by increasing C inputs. This can
be achieved using organic manures, compost and synthetic soil conditioners and soil conservation measures
on sloping lands. Policies and regulation and socio-economic factors at individual country level were found
to help reverse land degradation due to erosion. Ways of reclaiming salt-affected soils include: salt leaching
and drainage interventions, crop-based management, chemical and organic amendments, fertilizers, salt
tolerant plants, crop management and phytoremediation. Measures to contain degradation caused by oil
contamination include farming techniques that partly eliminate hydrocarbons through decomposition,
and bio-remediation using some grass species. With effective desertification control, the potential annual
C sequestration rate could reach values between 0.2 to 0.4 Pg C yr -1 , compared to the 1.0 Pg C yr -1 in drylands
worldwide. Ranking of soil threats is given in Table 13.3.
Status of the World’s Soil Resources | Main Report Regional Assessment of Soil Changes
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in the Near East and North Africa