The Pedological Variation in some of Soil Characteristics of Alkhaleej and Al-Aali Project in Al-Alam District / Iraq

The goal of research to study pedological heterogeneity in soil morphological and physical Characteristics in the Al-Khaleej and Al-Aali Al-Muwahed Project soils in Salahaldin Government. The (6) six soil pedon were chosen and their distribution based on the area of the soil series in study area. The soil morphologically properties were described according to soil survey staff, 2006. The soil physical properties (soil texture, Bulk density, and Compaction) were selected. The results show there is a variation in the morphological, where the thickness of the horizons differed and was the largest in the surface horizon at the peduns P1 and P3, while the color was found that all study sites are located within a page 10YR, which is the dominant wavelength for most Iraqi soils, while the soil texture was clayey and sandy in P1, P2, and P4, and mixed in P3, P5, and P6. The results showed that the soil texture ranged between admixture and admixture clay and sandy, and it was noted that the soil texture classes took the following order: sand > silt > clay, and it was noted that there was a predominance of sand content as it ranged between (417 and 722) g.kg-1 in the C2 horizon for each of P5 and P2 respectively, and a decrease was found in the bulk density in the surface horizons of the soils of the study sites and an increase in the average diameter weighted by the open ground.


Introduction
Pedological studies are considered the basis from which the rest of the sciences related to soil should start.These studies provide integrated information about the nature of soils, identifying their various morphological, physical and fertility characteristics.Thus, they provide soil users with a wide range of information to make the right decision in the field of using these soils.The study of the spatial variability of soil characteristics are of great importance in soil management for various agricultural applications, and the studies of spatial variances today are among the important means to raise the efficiency of soil surveying and classification.Soil variations and its heterogeneity are either spatial variability or temporal variability, and spatial variations are the most common.The study of spatial variability are an attempt to establish an effective management system in terms of fertilizer requirements in particular and water resources in general, and technological progress has helped a lot in this field, as it has become possible to give an accurate estimate of sampling and the relationship of that to the accuracy of measuring properties and predicting the characteristics of unspecified sites [1,2].The [3] show the differences between soil series based on variation in morphological 1259 (2023) 012030 IOP Publishing doi:10.1088/1755-1315/1259/1/012030 2 characteristics of soil layers, and recognition of the spatial variation of soil and plant characteristics in agricultural fields allows for estimating plant growth conditions and developing fertilizer recommendations required for the agricultural field and applying a good management system.The [4] found that variation in the morphological characteristics horizontally between the study sites and vertically within the same site, as it was found that the structure of the soil was between soft and sub anguler blocky in the surface horizons under the different vegetation covers compared to the fallow land site.The results of the physical analysis reached by [5] showed that there was a variation in soil texture in the vertical and horizontal directions in the study area, with the predominance of silt and clay particles and a decrease in the percentage of sand particles.The goals of research are study soil morphological and physical properties in Alkhaleej and Al-Aali Project soils in Al Alame City, Salahaldin Province, Iraq.

Study Area
The Alkhaleej and Al-Aali soils survey Project in Al Alame City, Salahaldin Province, Iraq were selected base on variation in soil physical and morphological properties.This project were prepared by Ministry of Agriculture and Irrigation/ general Authority of Agricultural Research / Soil Investigation Division in 1991.The project area is 42.5 km 2 and according to geographical coordinate data are located between longitudes 43˚ 40' 17.02" E and latitudes 34˚ 44' 10.19 N (Figure 1).Climate data have been collected during the years 2000-2022 from Tikrit Station.The mean minimum monthly temperature ranged from 6.46 ºC in January to 29.30 ºC in July.In addition, the mean maximum monthly temperature ranged from 13.40 ºC in January to 44.86 ºC in July.The mean monthly rainfall ranged from 0.0 mm in July and August to 37.12 mm in January.

Soil Pedon and Sampling
The (6) six soil pedon were selected and distributed based on the area of the soil series from the total area of the project.It is described morphologically according to the guid mentioned in [6].The soil samples were obtained from both horizon to determine soil colour, bulck density, and soil physical properties.Then, field information is collected for each site, which includes natural vegetation, land 1259 (2023) 012030 IOP Publishing doi:10.1088/1755-1315/1259/1/0120303 use, groundwater, and surface condition, slope, and management practices.Soil samples were taken to laboratory, and the soil physical Soil Texture were determined in the Department of Soil Science and Water Resources at the Tikrit University.

Laboratory Procedures
The estimation of Soil texture was estimated using a hydrometer described in [7].The bulk density was estimated using the Core Method described in [8].Soil Compaction was calculated using the equation given in [9].

The Thickness of the Horizons
It was noted from the results of Table (1) that the thickness of the horizons in the (P2, P3, P5 and P6) varied among themselves, especially in the surface horizon Ap, which is affected by the agricultural operations, and this may be due to the agricultural operations, especially plowing, in which the plow is used.As for the rest of the study sites, the thickness of the horizons differed depending on the nature of the agricultural operations, the agricultural system, and the type of vegetation cover, and this may be due to the repeated cultivation operations and the use of different types of plows.during the formation phase of this region.

Volumetric Distribution of Soil Classes
The size distribution of soil artifacts is one of the most important and stable morphological characteristics over time, which reflects the extent of the homogeneity of the parent material .The results indicate that the soil texture was dominated by sand and silt joints and the lowest clay content, and this is due to the sedimentation nature of the sedimentary plain soil adjacent to the Tigris River, and that the texture varied between Loam (highly fine) and the Sandy Clay Loam (medium soft) to the Sandy Loam (coarse).With the presence of Variation for the vertically separated, with the predominance of the Sandy Loam texture in the P1 and P4.The noticeable variation in the vertical soil texture within the soil series is due to the nature of the parent material and the extent of its homogeneity during sedimentation.Which is known as the phenomenon of stratification, which was referred to by [10] and [11].

Soil Construction
The results showed the presence of crumbly and granular structure in the plowed surface horizons, and that the dominant type of structure was the acute and non-acute block structure, but there was a difference in the degree of hardness, as it was low and medium hardness in the surface horizons and strong to very strong in the subsurface horizons, except for the horizons with content The soil is higher than sand, as it was weak in hardness and a relatively weak and broken construction.This is a result of the different soil characteristics, especially the content of organic matter, as well as the role of agricultural operations in sites that witness plowing operations and the dismantling of the surface horizons layer, while the subsurface horizons for this had a solid structure due to the weight of agricultural machinery.

Soil Consistency
The results showed that the soil consistency was in the surface horizons between fractured and slightly hard in the dry state and brittle to very fragile in the wet state, while the subsurface horizons did not differ much from the surface horizons.

Boundaries Between Horizons
The boundaries between the clear horizons are located in the surface horizons due to its exposure to external factors, especially the factors of vegetation and climate.While it was gradual to sudden in some subsurface horizons, so it was found that the boundaries between horizons are affected by the nature of the movement of soil components, their transmission, sedimentation, and the factors affecting the formation of horizons.

Root Distribution
It was found from the results of Table (1) related to the morphological description of the distribution of roots in the body of the soil, that their distribution was between the plentiful coarse and the average abundance, and that their sizes ranged between coarse and medium coarse in P2 and P6 respectively, while the rest of the peduncles had roots in them Small in number and small in size.

Volumetric Distribution of Soil Particles
The results of Table (4) indicate that the soil texture ranged between Loam and sandy Loam, and Sandy Clay Loam, and it was noted that the soil texture took the following order: sand > silt > clay, and it was noted that there was a predominance of the sand content as it ranged between (419.00 -745.66)g.kg -1 at the C2 horizon in P3 3 and at the C2 horizon of P4, respectively.It was also noted that the sand content had varied horizontally in the surface horizons of the soils of the study sites, as the value reached 439.00, 494.00, 524.00, 524.00, 599.00 and 616.91 g.kg -1 in P3, P6, P2, P5, P1 and P4, respectively.As for the vertical distribution of sand content, there was a variation according to the location, as it increased with depth at P1.It decreased relatively in the subsurface horizons, and then increased again in the horizons located below it.This is probably due to the nature of sedimentation and soil formation.As for the silt content, it ranged from (132.5) g.kg -1 at the C2 horizon of the P4 pods to (381.00) g.kg-1 at the C2 horizon of the P4 pods, and it was noticed that there was irregularity in the subsurface horizons.As for the content of clay, which is considered one of the important soil components that indicate its fertility and the degree of its development, the results show that it was relatively low in the study sites, as its values ranged between (88.00 -280.00)g.kg -1 No. 5 on the relay.As for the horizontal arrangement between the study sites, the following sequence was taken in the surface horizon: P2, P1, P4, P3, P5 and P6, and the values were 150.00, 180.00, 182.34, 225.00, 230.00 and 235.00 g.kg -1 , respectively, and this is probably due to the processes Repeated plowing leads to the destruction of coarse soil particles and increases the size of fine soil particles.

Bulk Density
The results presented in the table showed that the bulk density values were low in the surface horizons of the soil of pedons under the influence of vegetation cover, as these values reached (1.38, 1.38, 1.38, 1.42, 1.43 and 1.52) µg.m-3 for P2, P3, P4, P6, P5 and P1 respectively, and it was found that the bulk density values were relatively low in the subsurface horizons and for all study sites as well.Plant residues that increase the organic matter content, as well as the nature of the root system of the vegetation itself.This is consistent with [12] and [13].

Figure 1 .
Figure 1.Map of area Study and Iraq .
It is noted from the results the low distribution of compressibility values in the soil pedons at the different study sites, which varied between 49.62 in the C2 horizon of the No. 3 to 60.38 in the C2 horizon of the P1.The decrease in the values of this characteristic when cultivated land is attributed primarily to the decrease in agricultural operations at this type of land use, as well as the role of tree 1259 (2023) 012030 MOHAMMED AHMED KADHIM Classification of some soils of eastern Shatt Al-Arab region in Basrah province and evaluation of land suitability for agricultural purposes by using remote sensing technologies thesis College of Agriculture University of BASRAH [6] Soil Survey Staff 2006 Keys to soil Taxonomy tenth edition united states department of agriculture natural resources conservation serviceSWWashington DC [7] Gee and Bauder 1986 Partial size analysis in methods of soil analysis Part1Physical and mineralogical methods 2 ndedA Klute: 383-409 [8] Black C A DD Evans JL White LE Ensminger and F E Clark 1965 Methods of soil analysis Am Socof Agron No9 part 1 [9] Nikiforoff CC (1941) Morphological classification of soil stracture Soil Sci 52: 193 -211 [10] Buringh P CH Edelman 1955 Some remarks about the soil of the alluvial plain of Iraq South of Baghdad NetheriJ Agric Sci31:40-49 [11] Al-Dulaimi Iyad Abdullah Khalaf 2007 Soil color and reflectivity and their relationship to some physical and chemical properties of soil Master Thesis University of Mosul College of Agriculture and Forestry [12] Tanga AAT F Erenso and B Lemma 2014 Effects of three tree species on microclimate and soil amelioration in the central rift valley of Ethiopia Journal of Soil Science and Environmental Management 55:62-71 [13] Tate KW DM Dudly NK McDougald MR and George 2004 Effect of canopy and grazing on soil bulk density jRange management 57: 411-417