AGRICULTURAL CAPABILITY AND SUITABILITY OF WADI EL-FARIGH, WESTERN DESERT OF EGYPT

1- INTRODUCTION

 Nowadays, great attention is paid by the Egyptian Authorities for the establishment of new settlements and land reclamation projects to overcome the overpopulation

 problem. To overcome the problem and narrow the gap that exist between food production and consumption, Egyptian authorities adopted policies aiming at self-sufficiency in food production. This accomplished by horizontal extension of cultivated areas. This fact necessitates an essential demand for evaluating and classifying the soil according to its agricultural productivity. A modern nation, as a modern business, must have adequate information on many complex interrelated aspects of their activities in order to make decisions. Land use is the only one such aspect, but knowledge about land use and land cover has become increasingly important as the national plans to overcome the problems of hazard, uncontrolled development, deteriorating environmental quality, loss of prime agricultural lands, destruction of important wetlands, and loss of fish and wildlife habitat, Anderson et al. (2001). Land use data are needed in the analysis of environmental processes and problems that must be understood if living conditions and standards are to be improved or maintained at current level.

Inappropriate land use leads to inefficient exploitation of natural resources, destruction of the land resources, poverty and other social problems, Rossiter (1996).   Land evaluation is defined as the process of land performance assessment when the land is used for specific purposes, (FAO, 1985) or as all methods to explain or predict the use potential of land, Van Diepen et al., (1991). Information about soil and site properties is the raw materials for indicating land evaluation. These are often considered as land characteristics which can be directly observed or assessed. Indirect land evaluation normally uses a combination of soil characteristics and qualities, Beek (1978). Land evaluation includes qualitative and quantitative systems. Land may be evaluated directly by endeavors that are by growing crops. Direct evaluation is limited value unless the evaluator has the resources to collect a large amount of information, Olsen (1981) . Those most land evaluation systems are indirect. They suppose that certain soil and site properties influence the success of a particular land use in a reasonably predictable manner, and that the quality of land can be concluded from observation of those properties, Vink (1983). The first endeavor for rating the soil attributes was carried out by Storie (1932) whereas the soil attributes were categorized into three factors. It was revised and modified by, Olsen (1974). whereas the equation was recognized by the land productivity index. The latest modification of the Storie Index was published in 1978, which was also revised by UCDAVIS (2008) using the same concept for getting the index rating. With represent to this modification. FAO (1981) designed a framework for land evaluation to serve practical purposes. This framework aims to attain three basic principles, they are, i) land suitability is assessed and classified with respect to specific kinds of use, whereas each kind of use has own land requirements, ii) evaluation requires a comparison of the benefits obtained and the inputs required for different types of land, and iii) a multidisciplinary approach is required. Sys and Verheye (1978) made an attempt to evaluate the physical land characteristics for irrigation based on the framework for land evaluation. The detailed of this system will be illustrated later. Sys (1980) designed methods for rating the land characteristics and qualities, whereas the land characteristics are measurable properties of the physical environment related to land use. Computers have been applied to land evaluation at different level of detail. One of these computer programs is called Mediterranean Land Evaluation Information System (MicroLEIS), De La Rosa et al. (1992) for land evaluation in Mediterranean climates. This program includes a series of computerized models used for agro-ecological evaluation. They are based on productivity related aspects. Recently, the International Rice Research Institute developed a new computer program called Land Use Suitability Evaluation Tool (LUSET), Yen et al. (2006). This program is based on the criteria of FAO (1981) Framework and Sys et al. (1991). In this respect, the southwestern fringes of the Nile Delta constitute a promising area for land reclamation due to its favorable soil, availability of groundwater and accessibility to Cairo, Alexandria, Central Delta and the northwestern coast. So the area under consideration, Wadi El- Farigh, attracts the attention of several investments in the field of land reclamation. In this area several water wells were drilled for groundwater exploration and exploitation for the construction farms. Accordingly, it is recently subjected to intensive studies in the field of geology, pedology and hydrology.

Hence the studies which related to the groundwater potentialities of Wadi El Farigh proved that the quality and quantity of groundwater are fair enough establishing the agricultural projects including field crops, fruit, and vegetables.  So the present study aims at asses the land capability and land suitability of Wadi El-Farigh soils based on their physical and chemical characteristics.

2- MATERIALS AND METHODS

2.1. GENERAL OCCURRENCE AND FEATURES

The investigated area, Wadi El-Farigh, lies to the southwestern portion of the Nile Delta occupying a small part of the northern Western Desert. It is bounded by Cairo Alexandria highway from its east portion and extended westward to the western extreme of Wadi El Farigh basin. On the other hand, it is bounded from the north by Wadi El Natrun. The area is bounded by Latitudes 29° 59' 59.96" N to 30° 13' 08.57" N and Longitudes 30° 24' 57.14" E to 30° 58' 02.28" E,   (Fig. 1). The area of study occupies a desert portion of Egypt with extremely arid climatic conditions, while in the northern portions of the study area arid climatic conditions are prevailing. The prevailing climate is characterized by long hot summer, short worm winter, low rainfall and high evaporation intensities. The average minimum air temperature is recorded during February and it varies from 4.7 ºC (Maryuit station) to 8.5 ºC (Ganakles station), while the maximum air temperature is recorded in July, where it varies from 40.2 ºC (Giza station) to 33.5 ºC (Ganakles station), Egyptian Meteorological Authority (2006). The mean annual rainfall ranges between 13.8 mm/year (Maryuit station) and 18.3 mm/year (West Cairo station). The maximum rainfall value is recorded at January, February, March, November and December, while the minimum values were recorded in June, July and August. The evaporation intensity indicated that the average values of evaporation vary from 1.73 mm/day in January (winter) at Maryuit station to 17 mm/day in July (summer) at Cairo station. The relative humidity is generally higher in winter than in summer. The maximum and minimum relative humidity values are recorded in January and May respectively. It varies from 75.02 % at Maryuit station to 44.2 % at Wadi El Natrun station. The degree of aridity is determined by using the Emberger formula (1955) indicated that the desert condition is prevailing within the study area under consideration. As for the geological setting, the geological map established by El Abd (2005) indicated that the geological structure of Wadi El-Farigh is mainly placed in early Pleistocene age, late Pleistocene age and Quaternary age. The current study is depending on the recent study related to the geomorphic setting carried out by El Abd (2005) to recognize the main geomorphic unit covered Wadi El-Farigh. Accordingly Wadi El-Farigh is representing mainly by structural depression as a landform. Structural depressions constitute one of the main land features in the study area. As for the water resources. Groundwater is considered the mainly source of water for irrigation in the study area. Concerning the Miocene groundwater, the total salinities reflect that, the groundwater is mainly suitable for agriculture (TDS ranges from 179.45 to 286.25 mg/l) with exceptional cases where the groundwater salinity is over than 3000 mg/l, El Abd (2005).

2.2. SOIL SAMPLING AND LABORATORY ANALYSIS

Two different types of digital data were used in the present study. Landsat Thematic Mapper, ETM8, path 177 row 39, (Fig. 2) acquired on March 19th, 2013, Digital Elevation Model, EM-30m, (Fig. 3), acquired on June 26th, 2003, were provided by U.S Geological Survey Website accessed in 2015. The DEM was used to create and the general slope dominated through the study area, (Fig. 4). Based on the Landsat data of the study area was supervisory classified. 

Ground truth followed in this work was done by selecting several sampling sites for representing the two units which are the barren soils and cultivated soils. Accordingly, fourteen soil profiles were dug to 150 cm depth unless hindered by bedrock or water table. These soil profiles were pedo-morphologically described according FAO (2006). The exact location of the soil profiles (14) were precisely defined in the field using the Global Positioning System (GPS; Garmin Montana 650) and plotted on maps (Figs.3&4) Based on the pedo-morphological description, 40 soil samples were collected for the laboratory analyses. The collected soil samples were dried, crashed and sieved through a 2-mm sieve. The coarse size; gravels and stones, was determined volumetrically (Soil Survey Staff, 2004), while the fine size was taken and kept for physical, chemical, fertility analyses.

The routine analyses including soil pH, electrical conductivity, soluble cations and anions were estimated in the soil paste extract, (Bashour and Sayegh, 2007). Calcium, magnesium, chloride, carbonate, and bicarbonate were determined titrimetrically. Potassium and sodium was determined photo-metrically using Flame photometer. Finally, the sulfate was calculated by subtracting the total soluble anions from the total soluble cations. The total calcium carbonate was measured by treating the samples with HCl and the evolved CO₂ was measured manometrically, (Soil Survey Staff, 2004.). The organic matter content was estimated using Walkley and Balk titration method, (Bashour and Sayegh, 2007). The particle size distribution (size <2mm) was carried out by using dry sieving, Piper (1950).

 2-3- SOIL AND LAND CLASSIFICATION

Based on the field examination and laboratory analyses, soil classification was carried out to the sub group level using Key of soil taxonomy, Soil Survey Staff (2014). Two systems for land evaluation were carried out through two steps. First evaluate the Land capability classification by using Modified Storie Index Rating, UCDVIS (2008): The calculation was run and coding using Visual Basic for application under Microsoft Excel created by Aldabaa (2012). Second, evaluate the Land suitability classification by using Land Use Suitability Evaluation Tool (LUSET), Yen et al. (2006) a computer- based program.

 3- RESULTS AND DISCUSSIONS

3-1- THE SOIL PROPERTIES OF THE STUDY AREA

The area of the study occupies an area of about 200350 feddan. Based on the unsupervised and supervised maps the area is divided into two types of soils, namely cultivated soils and barren soils. The cultivated soils represented 28.35% of the total area, and the barren soils represented 71.65% (Fig. 5). The characteristics of each soil unite will be discussed as follow:

3-1-1- CULTIVATED SOILS:

This unit occupies approximately 58500 feddan, the soils of this unit are represented by 10 soil profiles (1 to 10). It is a cultivated area planted mainly with the following:

• Perennials: Mango, Olives, Orange and Grapes.
• Annuals: Alfalfa.
• Seasonal: Tomato, Eggplant, and Onion.

 The topography of this unite is almost flat with leveled slop, except the areas that are represented by soil profiles 1and 3 where the topography is gently undulating with gently sloping and nearly level respectively, and the surface is covered by residual plant leaves and shoots and scattered varisized rock fragments. Some pedological features have been detected in this unit such as, many fine to medium roots, many partially decomposed organic matter, and many fine to coarse rock fragments. The soils are generally deep where the effective depth is ranging from 100 to 150 cm. except the areas that are represented by soil profiles, 1 and 2 are very shallow and the depth almost 20 cm. Soil profiles, no. 8 and 10 are bounded by very consolidated layer .Physically, the soil texture of the study area is course textured (coarse to medium sand) while the structure and consistency are massive and soft. The gravel content is fluctuated between 0 to 24.05%. The high value of gravel is found in soil profiles no.5 and 7, and the gravels are accumulated on the surface. Calcium carbonate varies from 0.15 to 8.3% with remarkable increasing in the subsurface layers (Table 1). The chemical data, which are displayed in table 2, show that soils of this unit are generally free saline soils (<2 dS/m), except areas that are represented by profiles numbers. 5,6,7,8 the soils are slightly to moderately saline or saline (2-8 dS/m).The dominant cation is sodium followed by calcium then magnesium and the least dominant is potassium where as the dominant anion is chloride followed by sulphate then bicarbonate. The soil reaction is ranging from neutral to slightly alkaline (6.93-7.6) with few exceptions where the soil reaction is moderately alkaline (7.8-8.4) such as surface layers of the area that represented by profile no. 3 and subsurface and deepest layers of the area that is  represented by profile no. 5.

 The fertility status, which is shown table (1), revel that the organic matter content is ranging from 0.52 and 2.14 % and show accumulation  on the surface because these soils are cultivated. In general, the low value of organic matter is due to the hyperthermic temperature dominating in the study area. This type of condition leads to accelerate the mineralization processes leading to decrease the organic matter content. The available nitrogen is marginal whereas its values ranged from 30 to 76 mg/kg except areas that are represented by profile no.1 where it increases to reach 102 mg/kg. The soils are poor in phosphorus (less than 14 mg/kg) except areas that are represented by profiles numbers. 1, 2, 3, 6, and 9, where it increases to range from 18.6 -32.2 mg/kg, while they have no adequate content of potassium (< 120 ppm) except areas that represented by profiles numbers.1, 6, 8, 9 where its content is ranging from 121 to 762 ppm.

 3-1-2- BARREN SOILS

This unite occupies approximately 141,850 feddan, the soils of this unit are represented by 4 soil profiles (11 to 14).The topography of this unite is flat with level slop, and the surface is covered by sand sheet.

The soils are generally deep where the effective depth is 150 cm. Soil profiles no. 8 and 10 are bounded by much consolidated layer. Physically, the soils are of course texture 

(course to medium sand) and the surface layers are the coarser, while the structure and consistency are massive and soft. The gravel content is almost 22.5%, it is only occurred on the surface layers. The soils of this unit are slightly calcareous as the calcium carbonate < 2, (Table,3).The chemical data, which are displayed in table 4, show that soils of this unit  are generally  free saline soils (<2 dS/m).

Table 2: Some chemical properties of Wadi El Farigh, (Cultivated soils).

Table 3: Some Physical properties and Fertility status of Wadi El Farigh, (Barren area).

Table 4: Some Chemical properties of Wadi El Farigh, (Barren soils).

 The dominant cation is sodium followed by calcium then magnesium and the least dominant is potassium where as the dominant anion is chloride followed by sulfate then bicarbonate. The soil reaction is slightly alkaline (7.46 - 7.7) .