The Nature of the Effect of the Physiographic Location on the Spectral Behavior of Soil Horizons and the Distribution of Vegetation in Central and Northern Iraq

Three soil sites in central and northern Iraq were chosen to represent the nature of three physiographic units, namely, the mountainous unit, the undulating unit, and the river basin unit, to study the effect of unit variation on the nature of soil pedological properties and its spectral behavior. The results reached a diagnosis of the nature of the variation in the characteristics of the soil represented by the variation of the morphological characteristics represented by the difference of the wavelength if 5YR prevailed for the elevation within the mountainous unit and the soil color was dark reddish-brown, while in the rest of the units it was 10YR and the predominance of the light color was affected by the different physiographic units, which was reflected in the diagnosis of the surface diagnostic horizon Mollic horizon Representing the mountainous unit, and subsurface horizon representing the Argillic horizon, and Ochric horizon, and calcic horizon within the undulating unit, as well as the high content of organic matter and iron oxides in the mountainous unit, and the values reached 34.1 grams.9.02 as well as the variability of the soil separations, as the sand separation increased in the amount representing the unit of the river basin and reached 486 g.kg and The lowest value of the spectral reflectivity was in the region representing the mountainous physiographic unit, and it reached 35% for the subsurface horizon, while the reflectivity in the rest of the units rose to 62%. Absorption bands were diagnosed at wavelengths 1400 and 1900 nm. Near-infrared is represented by wavelengths 1750-2000 and at wavelengths 2000-2500. The values of the natural variation index for plants were 0.30 with an area of 4357 km2.


Introduction
The term physiographic is used to denote the nature of the topography of large areas in terms of varying heights in totality and the geographical shapes that result in the sum of a number of them to form one physiographic unit [1].[2] explained that the soils of Iraq differ among themselves as a result of the difference in soil formation factors, as they differ from one physiographic region to another.In addition, there are differences within one physiographic unit, which are due to a difference in heights, he original material, and the depth of the soil, in addition to the difference in topography.And natural plants .
The northern and north-eastern soils of the race are distinguished by the presence of relatively developed soils in some areas.This is due to the availability of some factors that help in this, foremost among which is the increase in rainfall rates with the increase in the density of natural vegetation cover and the change of its type towards trees, in addition to the increase in the period of time in which the original materials were exposed to the influence of factors Natural [3].Remote sensing technologies are an effective method for serving soil surveys, especially if they are associated with physiographic and geomorphological analyses, as they help in the integrated link between geomorphology and the processes of soil formation and formation, and reduce field observations necessary to set the boundaries of separation between soil units [4].[5], 2006 concluded in a study of the effect of the physiographic site on the genetic and evolutionary condition of some gypsum soils in Iraq, that the morphological characteristics showed a variation in the pedons of the study sites within their secondary physiographic units, and this discrepancy was reflected by the physiographic location and in turn reflects the nature of the variation in the locational factors of each soil such as topography, the degree of slope, and the variation in The chronological age and the rates of the amount of precipitation falling, as well as the variation in the physiographic and chemical characteristics, with the dominance of sand, then silt and clay, and a clear variation in the soil texture and the distribution of the separations with depth.Soil properties affect the response curves of the electromagnetic spectrum and the interpretation of remote sensing data.And interaction with electromagnetic energy according to their different physical and chemical properties, which causes a difference in the amount of energy emitted or reflected from these objects and within certain spectral limits, which facilitates the process of detection and distinction between the features of the earth's surface through the processes of interpreting the data recorded by the sensors.At the present time, research in quantitative spectral analysis to predict the behavior and properties of soil and motivated by developments in the field of statistics and spectral analysis within specific spectral fields and in several variables continues to progress and develop, as [6] showed that spectral analysis of soil properties showed three spectral regions that are sensitive to soil pedological and spectral properties, which are rays Visible near-infrared spectral region from 0.4 to 1 µm that contains spectral information on soil color, iron content, soil water, and organic matter content as well as nearinfrared (SWIR) that gives information on sulfates, carbonates, soil water, and matter content.Organic as well as thermal infrared area TIR that gives information on quartz, feldspar, silica minerals, clay, and organic compounds.Soil spectral reflectivity is a well-known technology for rapidly and quantitatively evaluating soil properties and has become a very useful tool over the past 20 years in the laboratory and field with increasing sensitivity to portable spectral ranges.[7].[8] concluded through his study a variation in the values of spectral reflectivity spatially according to the physiographic location as a result of the difference in the prevailing ground covers as well as the difference in the depths of groundwater and soil moisture, as the study area included five physiographic units (river shoulders unit, river basin unit, unit Irrigation canals shoulders, buried basins unit, high terraces unit).[9] concluded that all secondary physiographic units contain high levels of carbonate minerals, and also showed the significant effect of agricultural exploitation on most soil characteristics and in most soil characteristics and in the sites of secondary physiographic events.The results of the study showed that the spectral reflectivity characteristics can be used in the diagnosis It revealed the spatial distribution of the dominant taxonomic units for the two soil orders, Aridisols and Entisols.The study also created the possibility of isolation And the diagnosis of taxonomic units within the level sub-great group Haplogypsids Typic or Haplosalids Typic For the rest of the prevailing taxonomic units within the study area [10].This study aims to know the effect of the physiographic site on the nature of the morphological, physical, and chemical characteristics of the soil, as well as to know the effect of these units on their spectral behavior curve, to diagnose the spectral bands most capable of showing the spectral differences of these soils and horizons, and to know the nature of the distribution and density of the natural vegetation cover in these units, using remote sensing techniques.and geographic information systems.

Study Area
Several investigations and exploratory field tours were conducted within the study area to identify the nature of the physiographic units and their impact on soil formation and the nature of the distribution of vegetation cover.Three physiographic units were identified within the mountainous, hill, and river basin units.The first site was chosen within the mountainous physiographic unit in Sulaymaniyah Governorate, which is located in northeastern Iraq, between longitude 22-03-59-44-E and latitude 37-

Fieldwork/Morphological Characteristics
The samples representing the soils of the study sites were excavated within the physiographic units, and the surface and subsurface diagnostic horizons were diagnosed based on the morphological description form and the morphological characteristics ,horizon, horizon thickness, color in dry and wet conditions, soil texture, soil structure, soil consistency, Root distribution, Soil horizon boundary, with documenting the prevailing morphological features within the soil pedon according to soil survey manual [11].

Physical and Chemical Properties
It was estimated after taking soil samples from the field, which are models of the horizons of surface and subsurface soil deposits.The samples were air dried, then ground and passed through a sieve with a diameter of 2 mm, in preparation for conducting physical and chemical mineral measurements.Soil texture (sand, silt, and clay) were estimated using the international absorbent method described by [11], and reported in [13].The bulk density was estimated according to [14].Soil pH was measured by making an extract (1:1), using a device ((pH Meter), and according to [13].The electrical conductivity of the soil was measured by making an extract (1:1), using an (Ec Meter) device [13].The organic matter was estimated according to [15].The cation exchange capacity was estimated according to [16].Calcium carbonate (lime) was determined by [17].iron was determined according to [18].

Office Work
The spectral reflectivity curves of the selected soil models were measured from the surface and subsurface diagnostic horizons using a device measuring the spectral reflectivity ratio of the soil models within the wavelengths in a range between (350-2500) nm.The soil shall be prepared for measurement (i.e.air-dried and sieved through a sieve with a diameter of 2 mm) and the soil shall be kneaded in a Petri dish and the fumes emitted from the device shall be directed vertically on the model, which in turn reflects the radiation spectrally and according to the components of the model and expresses it as a percentage of white color in the form of a spectral curve and wavelengths Multiple, according to [19].The vegetation cover index was also calculated for satellite visualization and physiographic units within the study areas based on [20] and using the ARC GIS 10.8 program.

The Effect of the Physiographic Site on some Morphological Characteristics of the Soils of the Study Sites
The results of the morphological description of the surface and internal characteristics of the pedon of the study soils sites show in Table 1 that there is a state of variation in the nature of the morphology of these characteristics between the various other sites, due to; the influence of the nature of the physiographic sites, both within the main and secondary physiographic unit on a large scale, and the and the resulting effect on the nature of the activity of soil formation factors and processes.Especially the climate (rain and temperature) as well the the effect the vegetation factor, which is one of the effective factors in soil formation and development, as well as the influence of the nature of the physiographic site on the nature of the site conditions for each soil pedon, especially the topographic and the degree of slope, whose impact is reflected in the surface and internal characteristics of soil pedons such as type The nature of soil horizon, color, soil texture, soil structure, and soil consistency, the nature of the root distribution, and the nature of soil horizon boundary, these factors helped individually or collectively in causing a kind of variation in the horizontal surface of the soil unit and the internal vertical of the soil body or soil profile.The results a morphological description of the soil pedon located in the Bazian region, which is located within the physiographical unit (the mountainous region), indicating that it is located within the developed soils because it contains the surface diagnostic Mollic horizon, and sub-surface diagnostic horizon as the illuvail horizon (horizon B) representing Argillic horizon, which represents the horizon of collecting some colloidal materials transferred from the surface horizons and their collection.In the subsurface horizons as a result of the activity of some pedogenic processes, especially the processes of loss, illuvaition and removal of calcification, which helped to form a horizon that collects some materials, including clay materials and carbonate minerals, which are among the morphological features of the formation of illuvail horizons, according to soil taxonomy [21].And the climatic conditions represented by the increase in rainfall helped this region to diversify the vegetation cover, especially trees, as well as the relatively long life span and topography to activate some pedogenic processes responsible for the formation of the illuvial horizon which refers to the movement of soil components from the surface horizons to the subsurface horizons, especially carbonates and separable Clay may indicate a state of dissolution and transport in this region as a result of increased precipitation, which leads to the removal of binders and then the movement of soil components with depth, and this is an agreement with [22].The results of the morphological characterization Table (1) show the internal characteristics of the soil pedon, which is characterized by a dark color, especially for the surface diagnostic horizons, for the presence of good content of organic matter.It was also observed that the color persists with the depth of the horizon that follows it.The activity may be due to the dark color development process, which works to mix organic materials with the components of Mineral soil and give the soil a dark color.The color of the soil in the wet state ranged from dark reddish-brown at wavelength 10YR at the surface horizon A to reddish-brown at the horizon C k1 At wavelength 5YR, and value ranged between (3-6), while the chroma value ranged from (2-3) In dry state, the soil color ranged from reddish-gray at wavelength 5YR at the surface horizon A to light reddish brown at the horizon C k2.The brithness (value) ranged between 5-6, while the value of chroma ranged from (2-3).The dark color is attributed to the high content of organic matter, which amounted to 34.1 gm.kg. - In the surface diagnostic horizon A, as well as the effect of silt, which reduces soil color values, as silt is an effective soil component and has the ability to bind with iron compounds and organic matter, as well as its ability to retain moisture to a large extent, and this agrees with [23,24].It also shows the results of the morphological description of soil pedon located within the hilly unit of the undulating area in the Qara Hanjir region.The color of this pedon is distinguished by a yellowish-brown color in the wet state at wavelength 10 YR of all horizons, while the value of value ranged between (5-6) and the value of chroma (4-6).In the dry state, it was characterized by a light yellowish-brown color for all horizons, the value of value (6), and the value of chroma (4).The reason for this is attributed to the topography of the area that is not completely flat, as the slope reached 2-3%, which has a direct impact on the sites where soil residues, organic matter, and minerals are collected.And the salts that you consider to be components of soil differentiation in terms of wavelength and color purity [1].The soil texture class ranged between clay texture for the surface horizon and the horizon that follows it, and clay loam texture class for the subsurface horizon C k2.It was also observed that the aggregate of pebbles outside the body of the soil pedon, as well as the presence of rock pieces inside the soil pedon and within the horizon structure within the soil structure unit, is a distinctive morphological phenomenon confirming the influence of this soil pedon by the sources of sedimentation and the nature of the effect of the physiographic unit.As for the river basin unit, the dominant soil color of light color in its degree of gray and brown is not dark, and the high values of color density or brightness.

Particle Size Distribution
The results of the particle size distribution of the soil pedon, Table (2), indicate that there is a state of variation in the content of the study's soil components of the soil particles and the nature of their distribution with depth, within the physiographic units of the study areas.
The results indicate that the soil pedon located within the physiographic unit of the mountainous region with a high content of clay, then silt, then sand, as it reflects the nature of the clay-origin material of this soil, as it is noted in the first pedon that the percentage of clay increased in the subsurface horizons, as it ranged from (300-410).gm.kg -1 And that the increase in clay in horizon B may be attributed mainly to the role of the climate factor in a major degree due to the increase in the rate of rainfall in addition to the role of the vegetation cover and the root material.This is consistent with what was indicated by [25] that the process of transporting clay and its sedimentation is a pedogenic process that requires the presence of precipitates higher than evaporation that helps disperse and carry clay and transport it from the surface horizon to the subsurface horizons.The value of Silt for the first pedon ranged between (210-505) gm.kg-1.The lowest value was on horizon C k3 The highest value was at C horizon k2 , and the distribution of sand was low in the first pedon, as it ranged between (115-380) g.kg.
-1 .The lowest value on the horizon is B tk and higher in C k3 The reason for the low percentage of sand is due to the type of calcareous-clay origin material, weather conditions, and the type of wind and water deposits.
The results indicated that the soil pedons located within the physiographic unit (undulating area) did not show the requirements for achieving and diagnosing the argillic horizon, despite the presence of slightly high content of clay joints with the depth of the subsurface horizon in Table 2. Pedon.The reason for this may be attributed to the fact that this site is located in a sloping area, and the slope works to increase the movement of water to the side in the direction of the slope and thus reduces the entry of water into the soil body, which led to a decrease in the activity of soil formation processes and the transfer of soil components towards the surface horizons, and this is consistent with With [22].As the content of the clay separator for the third batch ranged between (355-420) g. kg -1 is the lowest value on the horizon.B k The highest value in sight 1 C k .As for the silt distribution, it decreased with depth (225-270) gm.kg -1 The lowest value on the horizon C k1 The highest value in the subsurface horizon is B k For the third point, the variation in silt proportions may be associated with the parent material and weathering conditions consistent with [26] As for the total sand separation, it ranged between (340-420) g.kg -1 The lowest value on the horizon B k The highest value in sight 1 C k For the third volume, the results indicate that the volume located within the physiographic unit (the river basin) has shown an opposite pattern to the volumes of the mountainous region and the undulating region, as the rule was for sand separation, then clay, then silt, as the content of the total sand separation ranged between (460-486) g.kg.
-1 The lowest value is in the horizon A and the highest value C k1 For the third place, since the rise and fall in the content of the total sand separation are affected by the nature of sedimentation and the physiographic location, and this is consistent with (Ali, 2022).We note from the results that the content values of the clay separation ranged between (294-420) g.kg.
-1 The lowest value in sight C k1 The highest value in the subsurface horizon of the second seat, while the distribution of silt separation ranged between (208-505) g.kg.
-1 The lowest value in the Ck2 horizon and the highest value in the B horizon For the first place, the high values of these classes confirm the occurrence of pedogenic transmission processes affected by the nature of the site variation of these classes within the different physiographic units.

Bulk Density
It is noted from Table (1) that there is a discrepancy in the bulk density values of the soils of the study areas within the physiographic units, where the bulk density values in all the study soils were related to the type of soil texture class, organic matter content, calcium carbonate content, and sometimes to the type of vegetation cover and the physiographic location of these areas.The results indicate that the values of the bulk density of the pedon located within the physiographic unit (the mountainous region) ranged between (1.41-1.76)megagrams.m-3,as it reached the lowest value in horizon A of the first pedon, and the reason for this is attributed to the increase in organic matter in the horizon.surface and this is consistent with [26,27,28], and the highest value is in the C horizon.The first pedon is due to the high content of calcium carbonate, especially in the subsurface horizons, which led to an increase in the value of bulk density in it and a decrease in the total porosity of the soil, which led to clogging of the pores, in addition to the role of calcium carbonate as a binder for soil particles, which increases its cohesion and integration, and this is consistent with With [30,24,26,31] for the values of the bulk density of the reservoirs located within the physiographic unit (undulating area), it ranged between (1.78-1.30)megagrams.m-3,as it reached the lowest value in the subsurface horizon of the third reservoir within the physiographic units (the river basin), as it was characterized by a decrease in the values of Bulk density, and the reason for this is due to the increase in the content of the sand separation in which the percentage of voids or pores is few but large and continuous, as well as the high specific weight of the sandy soil granules consisting of primary minerals, and this is consistent with both [32] that the increase in bulk density in The volume represented by the mountainous unit leads to an increase in the content of the separated clay, which leads to filling the pores, as well as an increase in the bonding strength between the soil particles, and thus a decrease in porosity, and an increase in the values of the total bulk density [33,26] as mentioned [34] that the soil content of clay, silt and organic matter is associated with an inverse relationship with the bulk density values with a significant effect in reducing it.In addition, the increase in calcium carbonate leads to an increase in bulk density values [31].

Chemical Characteristics
It is noted from the results, Table 3 , that the values of pH for all study areas located within its main and secondary physiographic units ranged from neutral to low, and this is consistent with [35,36,22,37,38], and that this range is due to the factors and processes of soil formation as well as the influence of calcium carbonate, and this is consistent with [39,40] Electrical conductivity, as the results indicate a decrease in the electrical conductivity values of the soils of the study areas, and this indicates that the study soils are not saline, as the values of the electrical conductivity of the potholes located within the physiographic unit (the mountainous region) ranged between (0.57-1.8).located within the physiographic unit (the confluent region) ranged between (0.26-1.4) decisemns-1 .We note from the results a decrease in the values of the electrical conductivity of the electrodes located within the main physiographic unit, and these results are consistent with [40] and with many previous researchers [42,43,22,38,40]who They confirmed that most of the soils of northern Iraq are non-saline and not subject to salinization.As for the values located within the physiographic unit (the river basin), they showed an opposite pattern to the values of the mountainous region and the undulating region in the values of electrical conductivity, as they ranged between (0.25-2.85) decimens. - This is due to the high groundwater, as well as the importance of salinization and the low internal drainage, and this is consistent with [9].Table 3.The results of Table (3) indicate that there is a discrepancy in the organic matter content of the aggregates located within the main and secondary physiographic units.It was noted from Table (2) that the values of organic matter for the aggregates located within the physiographic unit (the mountainous region) ranged between (34.1-5.3)g. kg -1 The lowest value in the subsurface horizon is C k3 The second meter has the highest value in the surface diagnostics A of the first meter, and this was identical to the spectral behavior of this horizon, as the value of its spectral reflectivity reached (26% for the horizon A) at a wavelength of approximately 1900 nanometers, and this was confirmed by [38,44]The increase in the content of organic matter in the soil clearly and effectively affects the values of the spectral reflectivity of the soil, and this means that whenever the content of organic matter in the soil increases, the values of the spectral reflectivity of the soil decrease.As for the organic matter content of the pretzels located within the physiographic unit (the corrugated area), it ranged between (31.0-4.4)g.kg.
-1 The lowest value in the subsurface horizon is C k1 The third and highest value in the surface diagnostic horizon A of the fourth, due to the vegetation represented by pine trees and the natural vegetation prevailing in this region as mentioned above in the morphological description, and this applies with what was indicated by [5,45] that the content of Soil content of organic matter depends mainly on vegetation cover, root system and climatic conditions.As for the minerals located within the physiographic unit (the river basin), they showed a different pattern in the values of the organic matter content, as they ranged between (4.2-11) g.kg.
-1 The lowest value in the subsurface horizon is C 2 The fifth degree has the highest value in the surface characterization A of the fifth degree, and this is due to the fact that these sedimentary soils are newly formed and undeveloped.It is clear from the observation of Table (2) that there is a large variation in the values of the exchange capacity of the soils of the study sites in all the main and secondary physiographic units, in line with the state of variation In the soil, which is the content of fine particles of clay and silt, and the content of organic matter.The values of the cationic exchange capacity of the pots located within the physiographic unit (the mountainous region) ranged between (16.61-24.52)cmol of charge per kg. - The lowest value in the subsurface horizon is C k3 The second volume has the highest value in the subsurface horizon (B tk ) for the first volume, and the reason for this discrepancy is due to the high content of clay and silt.This is due to the content of organic matter in the soil, as the values of the exchange capacity increase with the increase in the soil content of organic matter, and this is consistent with [46] (10.96-13.57)two cents of a shipment, kg -1 The lowest value on the horizon C 1 The highest value in the surface diagnostic horizon A of the fifth compound, and the decrease in the cation exchange capacity in this unit is attributed to the lack of organic matter content in this unit compared to the main physiographic units, in addition to the increase in its content of separated sand.These results are consistent with [47].Table (2) shows the variation in the content of total carbonate minerals for the minerals located within the main and secondary physiographic units.the values of calcium carbonate for pots located within the physiographic units (the mountainous region) ranged between (112-396) g.kg.
-1 The lowest value in the surface horizon A of the first place and the highest value in the subsurface horizon C k3 For the first place, this increase is due to the occurrence of a state of continuous dissolution and transport of this component with depth, and it may be associated with chemical conditions that make the carbonate in its dissolved form and in the form of solutions or suspensions and thus facilitate its movement with the soil solution.When the water reaches a state of saturation with carbonates at some depths, then happens Sedimentation in different soil horizons.The process of dissolving and transporting is known as decalcification, [48,22].This was confirmed by the results of the morphological description.Calcium carbonate clusters were seen in the form of white knots of different sizes in this area.The pedogenic evolution of calcium carbonate is also attributed to The high amount of precipitation that exceeds 632.6 mm/year, which is sufficient to dissolve this compound and move it, and then precipitate it at this depth, and this agrees with [22].The values of calcium carbonate minerals for the pots located within the physiographic unit (undulating region) ranged between (236-380) g.kg.
-1 The lowest value in the surface diagnostic horizon A of the fourth gauge and the highest value in the surface diagnostic horizon A of the third gauge, and it is noted from the results that the gain horizon B k For the third issue, this reflects the successive effect of the surface addition processes of carbonate minerals in the surface horizon, which were transported from oceanic sites by the processes of erosion and water sedimentation, which helped in the accumulation of carbonates.As a result of the availability of suitable moisture, it helped to dissolve and transport carbonate minerals from the surface horizons and collect them in the horizons close to the surface.kg -1 This is consistent with what was mentioned by [49].As for the minerals located within the physiographic unit (the river basin), the carbonate content ranged between (305-256) g.kg.
-1 The lowest value in the subsurface horizon is C 2 For the fifth and highest value in the subsurface horizon is C 2 For the sixth volume, it is noted from the results that these sites showed a similar pattern in the decrease in the values of the distribution of calcium carbonate, and due to the fact that the parent material is Alluvium sedimentary materials, there are no significant differences in the carbonate content in these sites, and this is consistent with [5].Table (2) indicates a variation in the values of total iron oxides for the soil values of the study areas within its primary and secondary physiographic units.These factors, together or individually, contributed to the occurrence of a state of variation in the activity of the different weathering processes, especially chemical ones, which helped to release iron in its free nature in the soil in different proportions within the study sites [26].
As the values of iron oxides for the minerals located within the physiographic unit (the mountainous region) ranged between (9.02-3.72)g.kg.
-1 The lowest value in the subsurface horizon is C k3 The first degree has the highest value in the surface diagnostic horizon A of the first degree, as this horizon is characterized by a dark reddish-brown color, as mentioned in the morphological description, and this high value is due to the containment of these soils to opaque minerals, and this is consistent with [26], and is also attributed to soil high content of organic matter and separated clay, The values of iron oxides for the pots located within the physiographic units (the wavy region) ranged between (1.8-8.63), the lowest value in the surface diagnostic horizon A of the third pot [50,51].
Where they confirmed the presence of a highly significant positive relationship between the content of organic matter and free iron oxides.As for the minerals located within the physiographic unit (river basin), the values of iron oxides ranged between (4.31-2.65)g.kg.
-1 .This decrease is attributed to the fact that these soils are sedimentary, undeveloped, with low content of organic matter, and separated by clay.

Spectral Reflectivity
The results of the spectral reflectivity curves and the spectral behavior of the surface and subsurface profile horizons of the aggregates located within the main and secondary physiographic unit showed that they were different in their spectral behavior, due to the influence of environmental conditions on the formation and development of these soils.At the longest wavelength of 1900 nm, as in the figure ( 2,3,4) which was identified as the main absorption band of water, the spectral reflectivity ratio at the 1259 (2023) 012021 IOP Publishing doi:10.1088/1755-1315/1259/1/01202110 surface horizon A of the first scale was 29% at wavelengths 1850,2100 nm, while the subsurface horizon B tk The spectral reflectivity was 35% at the wavelength of 1750, as well as the stability of the high reflectivity ratio at the wavelengths of 1800 and 1850 nm, as well as the diagnosis of deep water absorption bands at the wavelengths of 1900 and 1950 nm and weak absorption bands at the wavelengths of 1400 nm.As for the second block, whose spectral behavior was distinctive and different from the behavior of the first block, the surface, and subsurface diagnostic horizons were also distinguished by their spectral behavior within the same block and in the same physiographic unit, as the spectral reflectivity rate was 38% for the subsurface horizon C. k2 For the second term confined at wavelengths 1250,1800 nm, as for the surface reflectivity of the subsurface horizon C k3 For the second degree, it was 58 % at wavelengths of 1200, 1300, 1300 nm.
It is noted through the results a discrepancy in the spectral reflectivity values between the first and second places of the mountainous region, and this is due to a difference in the content of organic matter and iron oxides, and this is consistent with [23,52,53,54,55,56,38].As for the ridges located within the undulating region and the hills, the highest percentage of the spectral reflectivity of the 3rd radius at the subsurface horizon was 62% B. K 58% were recorded at the surface diagnostic horizon A at water absorption bands for both horizons at wavelengths 1600, 1650, 1700, 1750, 1800, 2150 nm.
As for the fourth degree, the highest value of reflectivity was recorded for the surface diagnostic horizon A of 38% at the wavelength of 1850 nm, and it was recorded at 52% for the subsurface horizon at the wavelength of 2100,2150 nm.Through the results, it is noted that there is a discrepancy in the spectral reflectivity values of the third and fourth premises, as the highest value of the spectral reflectivity of the third premises was recorded at the B horizon.This is due to the high content of calcium carbonate, and this is consistent with [56].The decrease in the reflectivity value of the fourth volume at the surface horizon is also attributed to the increase in its content of organic matter, as the more organic matter increases, the darker the color of the soil, and this is consistent with [57].It is noted through the results a slight difference in the spectral reflectivity values of the river basin beds.This is due to the fact that these soils are newly formed and undeveloped.It was also noted that the values of spectral reflectivity were higher in the secondary physiographic unit compared to the main physiographic unit, due to the high content of the sand separator, where the greater the sand separator, the greater the spectral reflectivity.

Vegetation Distribution in Physiographic Units
The results of the vegetative variation index of the physiographic units indicate elbaT 4 of variation in the distribution and density of vegetation cover within the secondary selected physiographic units, The categories of vegetation are divided according to [58,59] if the vegetation cover is medium in density with a number of forest trees represented by pine and oak trees, an area of approximately 4357.352475 square kilometers within the mountain physiographic units, The vegetation cover is formed in the province Sulaymaniyah is mostly of medium-density trees that form forests in many areas of the study area, and that (91%) of these forests are oak trees and (4%) are Pine trees, which also grow on the banks of rivers and mountain valleys are trees Willow, elm, walnut, wild fig

Conclusions
The nature of the variability of the physiographic units affected the morphology of the internal characteristics of the soil and the nature of the presence and diagnosis of the surface and subsurface diagnostic horizons of the soil pedons, as the surface diagnostic horizons represented by the Mollic horizon were diagnosed in the mountainous physiographic unit and the diagnostic subsurface horizon of Argillic horizon..While the surface diagnostic horizons represented by the Ochric horizon and the subsurface diagnostic horizons represented by the classic horizon were diagnosed in the undulating physiographic unit (the hills), while the genetic diagnostic horizons were not diagnosed in the physiographic unit representing the river basin unit due to the nature of soils being affected by river sediments.The physiographic unit has a clear effect on the nature of the variation of the soil texture class and the nature of the distribution of the soil particle if the soft texture class prevailed represented by the dominance of the clay and silt separated in the mountainous and wavy physiographic units (hills) while the sand separation had the dominance in the physiographic unit represented by the river basin.High organic matter content in the mountainous unit as a result of its influence on the nature of the vegetation cover distribution and climatic conditions.The highest values of iron oxides were found within the mountainous physiographic unit.The nature of the variability of the physiographic units affected the variance of their spectral behavior curve, which reflects the variance of their internal pedological characteristics if they were less spectral reflectivity of the region representing the mountain physiographic unit as a result of the influence of the nature of the dark color represented by the values of value and chroma, which reflects the formative nature of these horizons and their impact on the nature of their physiographic units as well as with the height of their material organic matter as well as the content of loam and soil moisture.While the spectral reflectivity was higher in the physiographic units represented by the undulating and hill unit and the river basin.The deep spectral bands were detected at 1900 wavelengths in magnitude representing the wavy physiographic unit as water absorption bands and for the surface and subsurface horizon.Diagnosis of spectral absorption bands of iron oxides at the wavelength of 1000 nm at the surface and subsurface diagnostic horizons of the sites located within the mountain physiographic unit.The highest percentage of spectral reflectivity was 62% at the sixth pedon within the river basin unit in the Altun Kupri township and at the wavelength 2100-2150 nm.The absence of dense vegetation cover in all physiographic sites, and medium vegetation cover prevailed in the physiographic unit represented by the mountainous unit in northern Iraq in Sulaymaniyah.
12-38-35 N-and within the village of Bazian, which is 30 km from the center of Sulaymaniyah Governorate.The second site is within the undulating physiographic unit within Kirkuk Governorate Northern Iraq between longitudes E 44-07-55-45 and latitudes 27-10-45-35-N in the village of Qara Hanjir.Pedons representatives of the soils of the study area were identified in Figure 1.Other surface samples were sampled by ten samples.The third site within the physiographic unit identified the river basin in the district of Alton Kobri, located between the longitudes 44-07-55-45-E and two latitudes 35-45-10-21-N.It identified Pedons representative of the soils of the study area, and samples of surface samples by ten samples.Mountainous unit undulating unit (the hills) River Basin Unit.

Figure 1 .
Figure 1.Shows the study areas within the selected physiographic units.

Figure 2 . 11 Figure 3 .
Figure 2. Spectral behavior of the surface and subsurface horizon within the mountain physiographic unit.

Figure 4 .
Figure 4. Spectral behavior of the surface and subsurface horizon within River basin physiographic unit.
, and wild apple to little vegetation cover within the undulating and hill physiographic unit in the Qara Hanjir region, is represented by grasses and some field crops grown in moderate areas and by following the system of fixed sprinkler irrigation.The river basin areas are represented by Tamarix and Willow trees and Alhagi mauroram, with an area estimated at about 2181.59685square kilometers.

Table 1 .
Table of the morphological characteristics of the soil pedon within the physiographic units.
Table of the physical characteristics of the soil pedon of the study area.
Table the physical characteristics of the soil pedon of the study area.

Table 4 .
Variation in the distribution and density of vegetation cover within the secondary selected physiographic units.