Author: Mahtab Hama Salih Faqe Qadir
Author contact: [email protected]
Publisher: University of Sulaimani
The study was conducted to assess land desertification, soil quality, land suitability and land
capability classification for drylands in some parts of Iraq and Iraqi Kurdistan Region.
The study area included arid and semi-arid lands located between longitudes 43° 25′ 41″-
46° 28′ 1″ E and latitudes 34° 18′ 33″- 36° 20′ 56″ N which include some parts of the
governorates of Sulaimani, Diyala, Kirkuk, and Erbil in Iraq covering area of 2645600 ha.
Twenty pedons were drilled and described morphologically. In addition to that, eighty nine
surface soil samples were taken from the neighboring area for these pedons. All soil samples
were taken to the laboratory and air dried, sieved through a 2mm screen and analyzed for
physical and chemical properties.
Desertification was assessed according to MEDALUS project (Kosmas et al., 1999b) and
using GIS technique.
According to the mean annual precipitation (mm), the study area was found to fall into three
zones included zone 2 [Arid (100-300) mm], zone 3 [Semiarid (300-500) mm] and zone 4
[dry subhumid (˃500) mm] as classified by (FAO, 1998). Soil quality was then assessed in
Land suitability classes for the study area were determined according the proposal of Sys et
The land capability classes and subclasses were arrived at according to the guidelines in Soil
Survey Manual (AISLUS, 1971).
The results obtained from this study were as following:-
1- Desertification assessment
a- Soil quality indicator (SQI)
– Soil texture ranged between class 2 (moderate) and class 3 (poor) with an area of 737100
ha and 1908500 ha, which covered 27.86% and 72.14%, of the study area respectively.
– The parent materials of all the soil of the study area were within class 2 (moderate).
– The index of rock fragment for all the soils of the study area was generally within class 3
(bare to slightly stony) which occupied 99.25% of the total area.
The index of soil slope in the largest part of the study area was within class2 (gentle),
with an area of 2561000 ha, which occupied 96.80% of the study area, and the remaining
space was between classes 1, 3 and 4, which occupied only 3.20% of total study area.
– The soil depth index was classified as class 1(deep).
– The soil drainage classes were found to be in class 2 (imperfectly drained) and class3
(poorly drained) with an area of 2150600 ha and 495000 ha at a rate of 81.29 and
– The organic matter index was divided into class 2 (good), class 3 (poor) and class 4 (very
poor).The area of class 3 was 2144300 ha with a rate of 81% of the total study area; thus
it succeeded the class 2 and class 4 that occupied the area of 224800 ha and 276500 ha
with a rate of 8.5 and 10.5% of the total study area respectively.
– Calcium carbonate index was found to be in class 3 (poor) which occupied 2608200 ha
with a rate of 98.59% of the total study area.
In calculating the weight of the soil quality indicators it seemed that the soil of the study area
could be divided into two classes, firstly, class 2 (2514700 ha), which occupied 95% of the
study area and secondly class 3 (low quality) with an area of 130900 ha which was 5% of the
b- Vegetation quality indicator (VQI)
– It was found that the plant cover to be in class 2 (low), so the study area was not well
protected against desertification.
– The risk of fires was found to be of class 2 (moderate).
– The drought resistance was found to be in class 5 (very poor).
– The study area was divided into two classes according to protection from erosion. The
area of class 3 (Low) was 803700 ha and the area of class 4 (very low) was 1841900 ha,
which occupied 30.38% and 69.62% of the total study area respectively.
Vegetation quality indicator consisted of class 2 (moderate quality) with an area of 760100 ha
and class3 (low quality) whose its area was 1885500 ha, they occupy 28.73% and 71.27% of
the total study area, respectively.
c- Climate Quality indicator (CQI)
– The study area was divided into two classes in terms of the quantity of precipitation.
Class 1(high quality) its area was 289800 ha, which was about 10.95% of the total study
area, but class2 (moderate quality) which occupied an area of 2355800 ha and was about
89.05% of the total study area.
– Aridity index for the study area was found to be in classes 4 and 5 which occupied an
area of 706500 ha and 1939100 ha with a rate of 26.70% and 73.30% respectively.
– The climate quality of the study area was found to fall in class 2 (moderate class).
d- Management quality indicator (MQI)
– Cropland for the study area was within the class 2 ( medium landuse intensity).
– Policy criteria was divided into three main classes, class 1 ( high), class 2 (moderate) and
class 3 (low) with an area of 486500 ha (18.39%),715000 ha (27.03%) and 1444100 ha
Management quality indicator for the study area was divided into three classes, includes the
class 1 (high) and its area was 456200 ha, class2 (moderate) its area was 747100 ha and
finally class3 (low) and its area 1442300 ha they occupied 17.24, 28.24 and 54.52% of total
study area respectively.
e- Environmentally sensitive areas to desertification (ESAs)
The most common type of Environmentally Sensitive Areas to Desertification (ESA) for the
study area was class C3 (Critical) with an area of 1112700 ha (42.06%) of the study area,
followed by classes C2 and C1 with an area of 759700 ha and 364000 ha which covered
28.71% and 13.76% of the study area respectively. The Fragile classes (F3 and F2) occupied
309300 ha and 99900 ha with a rate of 11.69 and 3.78%, respectively.
2- Soil quality for the study area
a. The clay% in zone 4 and zone3 was 38.6 and 37.5% respectively, with a significant
difference with zone2, which reached 20.7%, while there was not significant difference
between zone 3 and zone 4.
b. Insignificant differences (P= 0.163) was found between arid zones in means of bulk
density. Zone 4 outperformed zone 3, which surpassed zone 2 with values of
(1.66, 1.62 and 1.59) Mg m
c. Significant differences between zone3 and zone 4 in the mean organic carbon content at
rate of 0.90%, 0.81% respectively whereas zone 3 outperformed zone 4, and both
outperformed zone 2 significantly which reached 0.46%.
d. Soil pH did not show any significant variation across zone 2 (7.89), zone 3 (7.86), and
zone 4 (7.77) (P˃0.05). However, there were little differences in values, where zone 2
was higher than zone 3, which in turn surpassed zone 4.
e. Soils of all zones were not saline where values of EC were 0.48, 0.38 and 0.20 dS m
zone 2, zone 3 and zone 4 respectively, showing no significant differences among zones
of the study area.
f. There was no significant differences among zones in available potassium (P˃0.05), but
they varied in values, Available potassium was higher in zone 4 (0.614 Cmolc kg-1
followed by zone 3 (0.564 cmolc kg-1
) and zone2 (0.451 cmolc kg-1
g. Available nitrogen significantly varied between zone 2 in one hand, and zone 3 and zone
4 the other, with a value of 1.567 g kg
, 2.334 g kg
and 2.222 g kg
for zone 2, zone 3
and zone 4 respectively, but there were not significant differences between zone3 and
h. The available P did not show any significant differences in arid zone classes giving
values of 4.32 μg kg
, 5.65 μg kg
and 4.78 μg kg
for zone 4, zone 3 and zone 2
i. Concentration of exchangeable calcium did not show any significant variation across all
zones, the zone 4 has the highest value followed by zone 3 and zone 2 with values of
22.5 cmolc kg-1
, 22.3 cmolc kg-1
and 18.2 cmolc kg-1
j. Exchangeable Mg2+ showed no significant variation between zone 3 and zone 4, but they
varied with zone 2 by a mean value of (5.1, 7.4 and 1.6) cmolc kg-1
for zone 4, zone 3 and
zone 2 respectively.
k. The values of exchangeable Na+ were (0.215, 0.221 and 0.193) cmolc kg-1
for zone 4,
zone 3 and zone 2 respectively. Zone 2 differed significantly with zone 3, but not
significantly with zone 4.
l. The exchangeable Potassium K+
values were (0.40, 0.53 and 0.59) cmolc kg-1
for zone 2,
zone 3 and zone 4 respectively. Zone 2 varied significantly with zone 4, but there was
insignificant variation between zone 2 and zone 3, also between zone 3 and zone 4. The
pattern distribution of exchangeable Potassium K+ was similar to the available K+
m.Cation exchange capacity varied significantly within all arid zone classes. The highest
value occurred in zone 4 (26.1 cmolc kg-1
) followed by zone 3 (21.9 cmolc kg-1
zone 2 (15.7 cmolc kg-1
n. Significant differences were found among carbonate minerals content in arid zone
classes, least value appeared in zone 2 (316.4 g kg
) followed by zone 3 (204.0 g kg
and then zone 4 (171.0 g kg
3- Land suitability for wheat crops
a. The soil of the study area was deep and there were no depth limitations, with rate values
of 90, 95, and 100 for most pedons.
b. The soil texture rate value was ranged between 98 and 100 for the study area. In general,
this was not considered as limitation factor for growing of wheat crop.
c. The estimated value of carbonate was between 40-100, indicating that the carbonates; in
general, considered as a limitation factor for wheat growing.
d. The value of soil salinity rating was 95.2 and 95.3 for most parts of the study area
indicating that there are simple limitations.
e. The rate value of soil reaction was between 87-100.The degree of soil reaction did not
reach the alkalinity that could be effective in the growth of wheat.
f. The value of cation exchange capacity may have a different effect on soil suitability. In
some locations, the value reached 60 indicating a specific effect for soil suitability, but in
most other locations the value was 100 indicating that there was no limitation.
g. Values of organic carbon rating differed among the study sites, where in most sites it was
100 indicating no specific limitation where as it decreased in other sites to reach 73.
h. Flooding characteristic did not have any effect on soil suitability for wheat growing
throughout the study area, where the value was 100 for all sites.
i. Soil drainage did not play an important role in soil suitability and the rate value was 95
and 100 for most locations.
j. The rate value for base saturation was 100 for all sites of the study area. This indicated
that there was no effect on soil suitability.
k. The rate value for total cations was 100 for all sites of the study area. This indicates that
they had no effect on soil suitability.
l. The results showed the dominance of three classes that represent the land suitability of
the study area for Wheat crop as follows:
Class S2 (moderately suitable):- The land of this class could be moderately suitable
for wheat growth, with an area of 260800 ha, which is about 10% of the study area.
Class S3 (marginally suitable):- This land is characterized as marginal. Land area was
1844700 ha, which occupied 69.72% of the study area.
N1 (currently unsuitable):- This area was 539100 ha, which occupied 20.37% of the
4- Land capability classification
Land Capability Classes were divided into five main categories including:
Class II: This class covers 42500 ha, which accounts for 1.6%. Capability sub-class of
this class included IIe1 and IIs1e1.
Class III: The land capability class III covers an area of 77000 ha, which accounts for
2.9% of the total study area. Capability sub-class of this class included IIIe, IIIs, IIIew,
IIIc, and IIIce.
Class IV: Covering an area of 2090600 ha (79%). Capability sub-class of this class
included IVe, IVs, IVes, and IVc.
Class V: covering 420000 ha, which account for 15.9% of total area.
Class VI: covering an area of 15500 ha (only 0.6% from the study area).
Cite this article
Mahtab H. Faqe Qadr. 2020. CLASSIFICATION AND STATUS OF LAND DEGREDATION AND DESETIFICATION OF DRYLANDS IN KURDISTAN REGION-IRAQ, University of Sulaimani. Kurdistan Iraq