SOIL MAPPING OF WEST MENIA AREA, EGYPT USING REMOTE SENSING AND GIS TECHNIQUES.

Ismail M., El Ghonamey Y. K. and Ganzour Shimaa K. Soil, Water and Environment Research Institute. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 08 August 2019 Final Accepted: 10 September 2019 Published: October 2019

In recent years, thematic mapping has undergone a revolution as the result of advances in geographic information science and remote sensing. For soil mapping archived data is often sufficient and this is available at low cost (Green, 1992).
GIS was used to identify the potential for certain irrigated agriculture for some soils in Western Desert, Egypt (Ismail et al., 2012) Green, 1992 stated that integration of Remote Sensing within a GIS database can decrease the cost, reduce the time and increase the detailed information gathered for soil survey. Particularly, the use of Digital Elevation Model (DEM) is important to derive landscape attributes that are utilized in land forms characterization (Brough, 1986) Satellite remote sensing (RS) in conjunction with geographic information system (GIS), have been widely applied and recognized as a powerful and effective tools in analyzing land use categories (Ehlers et.al, 1990; Harris &Veturea 1995 andWeng, 2001). GIS provide indispensable tools for decision makers. Both RS and GIS techniques are considered very important geometric tools, which are fully utilized in the developing countries (Arafat, 2003). The integration of remotely sensed data, GIS and spatial statistics provides useful tools for modeling variability to predict the distribution, presence, and pattern of soil characteristics (Kalkhan et al., 2000). The potential of the integrated approach in using GIS and RS data for quantitative land evaluation has been demonstrated by Martin & Saha (2009).
Land capability is very important step in the reclamation process of the desert to determine the capability of soil cultivation to meet the requirement of the population. To make the evaluation were used by Sys rating systems a methodology produced by Sys et al. (1991). The Sys rating systems were suggested under the structure of the FAO Framework for Land Evaluation (FAO, 1976).
The objectives for this study are: (a) producing soil properties maps. (b) evaluating land capability in current and potential. (c) producing soil fertility maps.

Climate
As shown in Table1 the lowest value of rain (0.0) was in June, July and August while the highest value (3.43) in February. The maximum degree (38.77) was in July while the minimum degree (18.88) was in January. The lowest value of relative humidity (24.81%) was in May while the highest value (58.96%) in December. While The lowest value of wind speed (2.07 m/s) was in November while the highest value (3.61 m/s) in August.

Geology:
According to the geological map, produced by EGSA (1988) Moghra Formation is the main formation which represents an area of about (74.9 %) of the total studied area, covering the southern part, Gravely Platform Formation representing an area of (25.1 %) of the total studied area, which concentrated in the northern part of the studied area ( Figure 2) Color enhancement operations were used to create new images which is increased the amount of information that can be visually interpreted from the data (Daels, 1986).
Universal Transverse Mercator projection (UTM) were used as main projection of all data and output maps (Daels, 1986).
The geo-statistical analysis techniques were used to create Digital Elevation Model (DEM) using the semivariogram parameters (Stein, 1998) of contour lines and spot heights.

Field Work:
Seventy-two soil profiles were collected to represent the soils of the studied area. Morphological descriptions of soil profiles were descriped according to FAO, 2006. Soil samples were collected for laboratory analyses.
Nine water samples were collected from the wells in the studied area. Water samples were analyzed to determine some chemical properties according to USDA (2004). These included the electric conductivity (ECe), soluble cations and anions and Sodium Adsorption Ratio (SAR). Suitability of water for irrigation was determine according to the limitations outlined by FAO (1985).

Laboratory Analyses:
The collected soil samples were air dried, crushed and prepared for laboratory analyses, to determine soil chemical and physical properties according to USDA, 2004 methods: particle size distribution, electrical conductivity (ECe) in the soil paste extract, calcium carbonate, gypsum, macronutrients and micronutrients.

Producing thematic maps
The parameters of geo-statistical approach of the surface layer (seventy-two soil samples) were intered using Arc GIS 10.3 to produce soil salinity, soil sodicity, soil lime, soil gypsum, soil texture and soil depth maps. From the semi-variogram operation, it could be possible define which models fitted to the experimental semi-variogram values. The parameters of semi-variogram for best fitting a model were used to interpolate the thematic soil properties based on ordinary Kriging (Stein, 1998).

Land Capability:
Land capability for agriculture was assessed according to the method of Land Capability techniques using the rating tables of FAO (1985), Sys and Verheye (1978) and Sys et al. (1991). The method of land evaluation used according to the following equation: 100 100 100 100 100 100 100 Where: Ci = Capability index (%), t = Slope, x = Texture, d = Soil depth, l = Lime, g = Gypsum and n = Salinity and alkalinity

Producing fertility maps
According to geo-statistical analyses (Stein, 1998) the mas for macronutrients and micronutrients were produced using the classes in Table 2 Figure 3 shows the height areas located in the middle side and the elevation ranged from 139 to 159 meter above sea level. The low areas located in the northern and western areas for the studied area as the elevation ranged between 120 and 133 meter above sea level.

Physiographic soil map of the studied area
Based on sentinel-2 image taken during August 2019, digital elevation model (DEM), the topography and field check, the physiography of the studied area has been identified ( Table 3). The obtained data in (Table 3) showed that the representative soil profiles vary in their characteristics mainly due to they have been developed on different landscapeland form-Relief , i.e. alluvial plain, and terraces ( Figure 4) as shown in the following discussion.

AP112 unit
This soil is undulating topography belong to alluvial plain landscape and represented by 7 soil profiles Nos. 3, 6, 7, 8, 15, 18 and 27 .The soil texture vary between Loamy Sand and Sandy Loam, CaCO 3 between 4.3 and 11.3 %. EC value in dS m -1 ranged from 2.6 to 11.8 and ESP from 7.0 to 27.6 ( Table 4). Soil gypsum content vary between 3.2 and 7.9%.

AP121 unit
This unit is Almost Flat topography belong to alluvial plain and represented by 4 soil profiles Nos. 67, 68, 69 and 71 .The soil texture vary between Loamy Sand and Sandy Loam, CaCO 3 between 9.6 and 14 %. EC value in dS m -1 ranged from 1.7 to 9.8 and ESP from 2.6 to 9.2 (Table 4). Soil gypsum content vary between 6.6 and 13.5 %.

AP122 unit
These soils are undulating topography belong to alluvial plain and represented by 5 soil profiles Nos. 63, 64, 65, 66, and 72 .The soil texture vary between Loamy Sand and Sandy Loam, CaCO 3 between 4.3 and 14 %. EC value in dS m -1 ranged from 0.3 to 2.8 and ESP from 3.4 to 12.9 (Table 4). Soil gypsum content vary between 4.5 and 7.5 %.

AT112 unit
This unit is gently undulating topography belong to terraces landscape and represented by 3 soil profiles Nos. 33, 36 and 50 .The soil texture vary between Loamy Sand and Sandy Loam, CaCO 3 between 12.7 and 18.4 %. EC value in dS m -1 ranged from 2.5 to 5.3 and ESP from 5.2 to 6.5 (Table 4). Soil gypsum content vary between 6.3 and 14.3 %.

AT113 unit
This unit is undulating topography belong to terraces landscape and represented by 3 soil profiles Nos. 34, 40 and 47 .The soil texture is Sandy Loam, CaCO 3 between 10.4 and 16.9 %. EC value in dS m -1 ranged from 6.3 to 11.9 and ESP from 3.7 to 19.5 (Table 4). Soil gypsum content vary between 7.0 and 14.3 %.

AT221 unit
This unit is gently undulating topography belong to terraces landscape and represented by 4 soil profiles Nos. 52, 54, 55 and 62 .The soil texture vary between Loamy Sand and Sandy Loam, CaCO 3 between 10.0 and 19.0 %. EC value in dS m -1 ranged from 0.7 to 7.3 and ESP from 3.3 to 12 (Table 4). Soil gypsum content vary between 5.5 and 9.3 %.

AT222 unit
This unit is undulating topography belong to terraces landscape and represented by 6 soil profiles Nos. 57, 58, 59, 60, 61 and 70 .The soil texture vary between Loamy Sand and Sandy Loam, CaCO 3 between 5.0 and 14.6 %. EC value in dS m -1 ranged from 0.4 to 3.7 and ESP from 3.1 to 7.4 ( Table 4). Soil gypsum content vary between 3.3 and 11. %.

AT223 unit
These soils are undulating topography belong to terraces landscape and represented by 2 soil profiles Nos. 53 and 56 .The soil texture is Sandy Loam, CaCO 3 between 10.3 and 11.5 %. EC value in dS m -1 ranged from 3.0 to 11.8 and ESP from 8 to 15.6 ( Table 4). Soil gypsum content vary between 7.4 and 8.8 %.

Producing thematic maps of the studied area: Soil depth map
The total depth of soil profiles were between 55 and 140 cm with mean 105 and the standard deviation is 22.89. Figure 5 indicated that the soils of very deep whereas depth more than 120 cm cover about 1415 Feddans (15.59 % of the total studied area . The deep soils represented an area of about 4163 Feddans (45.86 % of the total studied area) where as depth is between 100 and 120 cm. the soils of moderately deep were about 3500 Feddans (38.55 %% of the total studied area) with depth from 50 to 100 cm.  Figure 6 indicated the dominant soil texture is Sandy Loam that representing an area about 6822 Feddans (75.15 % of the total studied area). On other hand the soils of Loamy Sand were 2256 Feddans (24.85 % of the total studied area).

Soil salinity map
Using geo-statistical approach for 72 soil samples for surface layer. ECe values ranged from 0.3 to 15.9 dS m -1 within mean of 5.85. The standard deviation is 4.3 %. As indicated in Figure 7 and Table 4 the soils of slightly saline (ECe less than 4) cover an area of about 27.97 % of the total studied area. The soils of moderately saline soils (ECe 4 -8) representing an area of about 38.82 % of the total studied area. The highly saline soils (ECe 8 -16) 33.21% of the total studied area.

Soil sodicity map
Exchangeable Sodium Percentage (ESP) ranged between 2.55 and 27.6 for surface layers within mean of 8.66 and the standard deviation is 5.16 %. Figure 8 and Table 4 indicated that the soils of non sodic whereas ESP less than 15 cover about 92.72 % of the total studied area. The soils of sodic-affected areas as ESP more than 15 cover about 7.28 % of the total studied area.

Soil lime map
Calcium carbonate was between 2.62 %and 23.2% with mean 11.28% and the standard deviation is 11.28%. Figure  9 indicated that the soils of moderately calcareous whereas CaCO 3 ranged from 2 to 10 % cover about 29.34 % (2664 Feddans) of the total studied area. The soils of strongly calcareous represented an area of about (6414) Feddans (70.66 % of the total studied area) where as CaCO 3 is between 10 and 25 %.

Soil gypsum map
Soil gypsum content was between 1.1 and 14.3 % with mean 7.32 % and the standard deviation is 2.8 %. Figure 10 indicated that the soils of Slightly gypsiric whereas gypsum content less than 5 % cover about 5.88 % of the total studied area (533 Feddans). The soils of moderately gypsiric represented an area of about 8545 Feddan (94.12 % of the total studied area) where as gypsum content is between 5 and 15 %. Land Capability for agriculture Current land capability Current land capability refers to the capability for a defined land in its present condition without major improvement (FAO, 1976). It may refer to the present use of land, either with existing or improved management practices, or to a different use. The current capability of the studied area is estimated by the present land characteristics and their ratings outlined by Sys et al. (1991). Figure (11) shows a detailed description of the current land capability subclasses in the studied area Using ARC GIS to overlay all factors i.e. depth, texture, topography, salinity, sodicity, and lime (calcium carbonate) to produce land capability map (Figure 8). One order (S) and four subclasses (S 2 x, S 3 t, S 3 d and S 3 d, t) were recognize in the studied soils, the current capability classes is given as follows. Potential land capability for this propose, the land utilization is applicable after executing specified major land improvements as proposed in the current study according to their necessity. In The studied area, land improvements is required to management the severity of limitations exiting in the area under consideration such as; Leveling of undulating surfaces of high and low land area, modern irrigation systems such as drip and sprinkler to save irrigation water and prevent rise of ground water table. Add organic fertilizers, green manures and soil conditioners to increase soil fertility and improve the physical and chemical soil properties.
Potential land capability of studied soils as shown in Figure (

Producing fertility maps of the studied area: Available Nitrogen
The data in Table 4 reveals the available nitrogen content was between 21 and 79 mg kg -1 with mean 56.4 and the standard deviation is 12.77. Figure 13 revealed that the soil of low nitrogen was the smallest area (222 Feddans, 2.45 % of the total studied area). While the soils of medium were the large class (8856 Feddans, 97.55 % of the total studied area).

Figure 13:-Soil available nitrogen content Available Phosphorous
All values for available phosphorous were less than 5 mg kg -1 (Table 4), so all soils is one class (low). Available phosphorous ranged between 0.05 and 3.49 mg kg -1 with mean 0.66 and the standard deviation is 0.56.

Available Potassium
The data in Table 4 reveals the available potassium content was between 28.2 and 416.8 mg kg -1 with mean 179.06 and the standard deviation is 104.53. Figure 14 revealed that the soil of low potassium class (6128 Feddans, 67.5 % of the total studied area). While the soils of medium class were (2932 Feddans, 32.3 % of the total studied area). The high class potassium was (18 Feddans, 0.2 % of the total studied area).  Table 4 indicated that the content of available iron was between 0.47 and 12.35 mg kg -1 with mean 3.41 and the standard deviation is 2.93. Figure 15 revealed that the soil of low iron class (6768 Feddans, 74.56 % of the total studied area). While the soils of medium class was (2223 Feddans, 24.48 % of the total studied area). The high class iron was (87 Feddans, 0.96 % of the total studied area).

Available Manganese
The data in Table 4 reveals the available manganese content for all values less than 2 mg kg -1 so all soils are low class. Available manganese ranged between 0.05 and 1.97 mg kg -1 with mean 0.91 and the standard deviation is 0.55.

Available Zinc
The data in Table 4 showed the available zinc content for all values less than 1mg kg -1 so all soils are low class. Available zinc ranged between 0.006 and 0.9 mg kg -1 with mean 0.19 and the standard deviation is 0.18.

Available Copper
The data in Table 4 indicated the available copper content for all values less than 0.5 mg kg -1 so all soils are low class. Available copper ranged between 0.002 and 0.18 mg kg -1 with mean 0.011 and the standard deviation is 0.03.

Water quality for irrigation
The ground water is the only source for irrigation. The chemical analysis was done to detect the degree of water quality for irrigation (FAO, 1985) as follows: TDS (mg l -1 ) Water quality 0-600 Suitable for irrigation 600-1100 Moderately suitable for irrigation 1100-2100 Low suitable for irrigation More than 2100 Not suitable for irrigation unless for highly tolerant salinity crops The water quality for water samples from 9 wells were classified as (C3-S1) class (high salinity and low alkalinity) for all water samples except for samples Nos. 4 and 8 is (C2-S1) (moderately salinity and low alkalinity). On other hand water sample No. 7 is (C4-S1) (very highly saline and low sodium water) not suitable for irrigation purposes where it contains more than 2100 mg l -1 salts (Table 5).