Usage of Geographic Information System for Management of Soil Fertility, Egypt

The current work was implemented to introduce an exclusive description for fertilization of an area equivalent to 50459.04 hectare situated along El Bahria Oasis Road – Giza Governorate, Egypt. GIS and GPS techniques were implicated in this study. Soil survey was carried out where the main physical, chemical properties and fertility parameters were engaged. The studied area was classified into two orders; Aridisols and Entisols. Geographic database for the soil properties and nutrients under study were built up and digital maps were produced. Land evaluation was done according to Storie & Sys and others; Land capability of the studied area showed four classes namely; II, III, IV and V with respect of storie). The land suitability for some crops (winter crops, summer crops and orchard trees) were appraised for the area under investigation and exported to GIS to be displayed in digital maps. Taking into account the contents of the nutrients present in soil the Fertilizer requirements for suitable crops were estimated; spatial analyst tools in Arc/GIS were used to create digital maps for the requirements of key figures nutrients (N, P, K) calculated in kg /hectare; The resulted map for fertilizers needs could be considered of enormous potential for precision farming application.


Introduction
Global demand for food is tremendously rising due to higher population growth rate and the developing countries would share the highest percentage of such demand. Therefore, they should swiftly shift from conventional farming to precision one even at the rural districts and land reclamation; in order to boost the cultivation production. Land evaluation provides essential information on land resource, landform, land use, vegetation, climate and soil properties for a defined area. Concepts, definitions and case studies of land evaluation can be found in numerous publications such as (Storie, 1932 and1978;Sys and Verheye, 1978and Sys, et al., 1991. Land capability classification: USDA, (1973) has provided specific guidelines for land capability classification. This system has been adopted to include eight classes of land designated by Roman numerals. The risks of soil damage or limitations in use become progressively from class I to VIII. Capability grouping of soils is designed 1) to help landowners and others to use and interpret the soil maps; 2) to introduce users to the details of the soil map itself and 3) to make possible broad generalizations based on soil potentialities, limitations in use and management problems. The capability classification provides three major categories of soil groupings: I. capability unit, II. capability subclass and III. Capability class according to USDA, (1961 and2015) and Office of Environment and Heritage, (2012). The third and broadest category in the capability classification places all soils in eight capability classes . Tideman, (1990) confirmed that land capability is governed by the different land attributes such as types of soil "depth and texture, underlying geology, topography, hydrology… etc." land has a limited resource and with increasing population the demands for land become more competitive. Any given area of land can have a multitude of potential uses and all may need to be considered in planning and management of land resources. As for land suitability classification; Beek and Bennema, (1972) stated that it is a function of crop requirements and land characteristics i.e., it is a measure of how well qualities of land unit match the requirements of a particular form of land use (FAO, 1976and Sys et al., 1991& 1993. Suitability analysis can answer the question (what is to grow where?), in order to define suitability of an area for a specific practice, several criteria need to be evaluated (Belka, 2005). Depending on the land use limitations FAO, (1976) classified land suitability into two orders and 4 classes. Land suitability orders indicate whether land is assessed as suitable or not suitable for the use under consideration; Order S suitable "land of which having sustained use and expected to yield benefits which justify inputs, without unacceptable risk of damage to land resources", Order N suitable "land of which have qualities that appear to rule out sustained use". Nonetheless, the 4 classes are class; S1 "highly suitable", class S2 "moderately suitable", class S3 "marginally suitable", class N1 "not suitable" and class N2 "permanently not suitable". Evaluation of land capability for reclamation an area requires data include, chemical and/or physical soil properties and topographic level. One of the sustainable agricultural indicator is to cultivate crops that physically suitable for the soils. Land suitability analysis for crops is a prerequisite to achieve optimum utilization of available land resources for sustainable agricultural production.
Combination of GIS, geospatial mapping and RS technologies is a very powerful tool to achieve such task. Moreover, it helps in building up geographical database, in form of digital maps, for plant nutrients needed for relevant crops. Thereafter, appraisal the actual amounts of various fertilizers needed for the yields would be grown therein; taking into consideration the nutrient levels in soils, the grown plant needs and soil characteristics. Such specific digital maps can rationalize the consumption of the mineral fertilizers used. Egypt pays great attention to the development of its agricultural resources, either through the land reclamation or through maximizing the productivity of soil unit. The current study area is a part of the future promising governmental land reclamation and for developing modern rural districts to interact with the state development plan the current work was accomplished. The ultimate goal of this study is mainly to contribute in achieving the strategic objectives of such plan. In more specific words, this work aims to achieve the following objectives: ▪ To execute soil survey for an area suitable for agricultural development of Egypt being incorporated in land reclamation plan. ▪ To build up a geographic soil database for the main soil physical, chemical properties and nutrient contents of study area and depicting digital maps for the different soil characteristics and nutrients contents. ▪ To perform the land capability classification and land suitability for some crops. ▪ To establish a framework of geographical database for calculating fertilizer requirements based on soil characteristics and land use types.

Study Area
The study area is virgin; it located at the Giza Governorate, Egypt and situated in the Western Desert, at El Baharia Oasis Road, It is in the extend of the south western direction of Wadi El Fargh. The area is bounded by the following four points:

Map (1): General location of the study area in Egypt
Map (2): Location map of the tested soil profiles

Soil survey execution for identifying the main soil physical, chemical properties and Nutrient status in the study area
A grid system was overlaid on the study area with a lag of 3 km distance to identify the location of the observation points. This was followed by a field work to collect representative soil samples; fifty seven soil profiles were allocated to represent the study area, Map (2). The soil profiles were dug to a depth of 150 cm unless opposed by bedrock or extremely hard layer. A total number of 178 soil samples were collected from the layers in order to determine the main soil physical and chemical characteristics as well as nutrients levels. The definite locations of the study soil profiles were recorded using GPS (MODEL GARMYN), which exported to ARC/GIS. A point map was created to represent the locations of the study soil profiles and used to create the geographic database for the different soil attributes.

Physical and chemical soil properties
▪ Particle size distribution was estimated using the International Pipette Method, described by Piper, (1950). ▪ Total calcium carbonate content was determined volumetrically using Scheibler's Calcimeter (Wright, 1939). ▪ Organic matter was determined using the Walkley and Black method (Jackson, 1967). ▪ Soil pH was measured in 1:2.5 soil water suspensions by using a pH meter (Van Reeuwijk, 1993). ▪ Soil paste extract was prepared for each soil sample, where determinations, Electrical conductivity (ECe), (CONDUCTANCE METER-YSI MODEL 35)&Soluble anions and cations (Jackson, 1967). ▪ The Gypsum content of soil was determined by precipitation with acetone according to Schoonover, (1952). ▪ Sodium Adsorption Ratio (SAR) a ratio for soil extracts used to express the relative activity of sodium ions in exchange reactions with soil according to Bower et al., (1952). "SAR=Na/ Ca+Mg /2" ▪ Exchangeable Sodium Percentage (ESP), it calculated by the formula according to Allison et al., (1954).

Nutrient status
▪ Total nitrogen was determined by Kjeldahl methods using sodium hydroxide and boric acid according to Jackson, (1973). ▪ Total contents of macronutrients (P and K) in soil samples were extracted through digestion with perchloric-hydrofluoric acids (Hesse, 1971). ▪ Total phosphorus was determined using ascorbic acid method described by Houba et al. (1995). Where light absorbance was measured by Spectro-Photometer at 882 nm. (Model SPECTRONIC 21D). ▪ Total potassium was measured using Flame Spectro-Photometer (Model JENWAY PFP7). ▪ Available nitrogen was extracted from 5.0 g soil with 50 mL 2 M KCl (Page et al., 1982), and determined using Kjeldahl methods (Jackson, 1973). ▪ Available phosphorus in soil was extracted using sodium bicarbonate solution, 0.5 M at pH 8.5 according to Olsen et al., (1954) and determined used ascorbic acid (Van Reeuwijk, 1993). Absorbance was detected using Spectro-Photometer at 882 nm. (Model SPECTRONIC 21D). ▪ Available potassium in soil was extracted using 1 N ammonium acetate solution" NH4OAC "at pH 7 according to Page et al., (1982) and determined using flame spectrophotometer (Model JENWAY PFP7). ▪ Available Fe, Mn, Zn and Cu were extracted using DTPA method (Lindsay and Norvell, 1978).
Available tested micronutrients were determined by Atomic Absorption Spectrophotometer, (Model GBC 932).

Coding soil database attributes and obtaining digital map
Results of physical, chemical properties and nutrient contents of the tested soils were entered as soil attributes for the soil profiles map. The attributes were coded using Arc/GIS (V., 10.3) as a geographic database. IDW Interpolation type was executed to produce the different soil properties and nutrient contents digital maps.

Soils classification
Soil classification is carried out according to USDA, (2014).

Land capability classification maps
Land capability was done using the rating suggested by Storie, (1932 and1978) where, application in this equation: Where; Ci= Capability index, A= Soil depth, B= Texture, C= Slope, X1= Salinity, X2= CaCO3 content and X3= Gypsum content.

Mapping land suitability for some crops
Land suitability was done using the rating tables suggested by Sys et al., (1993) for alfalfa and sugar beet (winter crops); where, maize and sorghum (summer crops); olives and citrus (orchard trees).
Current and potential "land capability" and/ or "land suitability for crops" was calculated for the study area. The current "land capability" and/ or "land suitability for crops" indicates that "capability" and/ or "suitability for selected crops" of the area under the prevailing conditions of the soil. Whereas, the potential "capability" and/ or "suitability" reflects the "land capability" and/ or "suitability for the same selected crops " of the area but after curbing and improving limiting factors such as salinity.
The evaluation is carried out by comparing the land characteristics with the limitation levels of the requirement tables. In addition, "capability index" and "suitability index for selected crops" were calculated using Stories equation and were added as open attributes table for the soil profiles point map. The attributes were coded using Arc/GIS as a geographic database for the profiles point map were used for interpolation (natural neighbor) activities then create symbolical/classified to produce capability and suitability digital map of different classes.

Framework of fertilizer requirements calculation
The fertilizer requirements of the study area were calculated using the geographical database through the capabilities of Arc/GIS then fertilizer requirement maps were produced according to the prevalent soils characteristics and the proposed land use type.

Results and Discussion
*All Maps represent physical, chemical and nutrient content for average surface and subsurface layers of the study area.

Soil depth:
The study area is considered in terms of land use as virgin area with flat to undulating desert formations. Some of normal faults with strike slip movements seem to have affected the location. As indicated from Map (3), an area of approximately 2000 hectare there are moderately deep profiles, e.g., profiles 7, 13, 14, 15 and 21. According to the proposed limits after FAO (1990), while, 96.04% of the study area is considered very deep soils that could be suitable for either shallow and deep rooted cultivation.

Soil texture:
Soil texture is considered one of the most important soil criteria affecting soil behavior and land management, and it influences a number of physical and chemical soil characteristics. The obtained results showed that sand fractions dominated the soil particles in all the study soil samples, Map (4). Particle size distributions for the study soils are presented in Maps (5).
The results revealed that most of the study area exhibits coarse sand texture, especially in the surface layers samples, and sometimes with medium to coarse textured as the texture varies between sand to sandy loam excluding profile 40 which possess sand clay loam due to the occurrence of shale deposits in that location. It appears that the soils under consideration may reflect multi-depositional regimes throughout soil profile layers. Desert pavement is commonly observed in the study area as high gravel contents were concentrated on the soil surface.

Map (3): Depth of soils in the study area
Map (4): Sand contents Map (5): Distribution pattern of textural classes 3.1.3. Soil salinity and alkalinity: Salinity is one of the main factors which limits the distribution of plant communities in their natural habitats and is causing increasingly severe agricultural problems.
The study soils are characterized by different salinity levels ranged between non-saline (0.79 dS m -1 ) to extremely highly saline (110.40 dS m -1 ). The highly saline values may be related mostly to salinity inherited from dominating Eocene limestone. Whereas, the lowest EC values were more related to the permeable coarse textural soils. The distribution pattern of soil salinity in the study area, Map (6) shows that more than 31% of the area is non-saline, 1741.86 hectare to slightly saline soils, 14035.59 hectare. This confirms the potentiality of the study area for agriculture. The highly saline and very highly saline soils constitute only 22.16 % and 3.89 %, respectively.

Soil reaction-pH:
Having the correct soil pH is crucial for the healthy plant growth as it affects the amount of nutrient available to plants (Nur et al., 2014). Soil pH is considered as one of the most essential factors influencing plant uptake of trace element (Kabata-Pendias, 2001). The variation in soil pH usually is related to parent material, rainfall, topography and organic matter. From the obtained pH data in the current study, Map (7), the study soils are slightly alkaline to alkaline with pH values between 7.23 to 9.16. The alkaline pH values indicate that the soils are saturated with basic exchangeable cations besides the occurrence of free CaCO3 in the soil. The most majority of the investigated soils have pH values in the range of 8.00 to 8.38.

Organic matter content:
Organic matter influences many soil characteristics including color, nutrient retaining or turnover and stability, holding capacity and soil aggregations (Tagwirg et al, 1992). The data of OM% exhibited in, Map (8), show that the study area have general extremely low content of organic matter as the values are ranged from 0.02 to 0.34%. This is mainly could be related to the non-arable desert nature with no vegetation cover due to scarcity of precipitation and to the common coarse texture prevailing in the area.

Gypsum content:
Gypsum presence imparts to soils properties and affects soil development including soil morphology, water holding capacity, nutrient, water availability for plants, root growth and the standard concepts of soil texture and rapture resistance, (Susan et al., 2014).

Exchangeable Sodium Percentage (ESP):
The detrimental effect of sodium in soils has been widely investigated. It has been reported, for example that high ESP may enhance chemical dispersion of soils, which leads to crust formation and decreases infiltration rate (Robinson and Phillips, 2001). Soils ESP and SAR are positively related because soils solution cations and exchangeable cations are nearly always in equilibrium with each other (Singer and Munns, 1996). Dispersion problems may appear at a greater ESP or SAR. A limit beyond which the ESP is harmful to the soil structure is difficult to assess especially in sandy soils. In general, no problems are experienced in soils with ESP<15 under arid climate. However, the ESP is not the only indicator of soil stability because the salt concentration of the soil solution also affects soil dispersion. The distribution pattern of the obtained ESP values is illustrated in Map (11)

Nutrients contents in the study soils
3.2.1. Total macronutrients contents: Many investigators concluded that a soil system is a function of soil potentiality for essential plant nutrients, which was usually, related to the nature of soil parent material. This may result from combination of compositional differences between the physical and chemical conditions in soils (Officer et al., 2006). The soil factors which influence the contents of the primary macronutrients (NPK) are mineralogical composition, soil texture, organic matter content, soil reaction, calcium carbonate and soil depth. The following discussion will be devoted to discuss the contents of NPK; the key players for the plant product.
a. Nitrogen; The obtained results are illustrated; the soils are very poor in total N content as it ranges between 30.5 to 140.0 mg kg -1 , apart from profile 40 that recorded 350 mg kg -1 , in top soil. The lowest total N value (0.02%) was recorded in a profile bottom, whereas the highest value (0.34%) was recorded in a profile surface.
b. Phosphorus; Values of total P differed widely in the study soils depending on the type of deposits. Total P contents mostly vary between 88.7 to 191.6 mg kg -1 , apart from the shale deposits in profile 40 that have 327.5, 356.2 and 342.3 mg kg -1 in its successive layers respectively. In general it seems that marine and lacustrine deposits present in the study area played a substantial role in elevating total P content in the soils.
c. Potassium; Concerning the data of total K recorded in the different study soil, it ranged between 1160.2 to 9431.6 mg kg -1 with no obvious distribution pattern trend through the profiles depth. The majority of study area soils possess total K values ranged between 3000-5000 mg kg -1 . Such higher value could be ascribed to the mineralogical composition. In this respect Ibrahim (2001) demonstrated that higher K value could be related to occurrence of feldspars arising from the recent lacustrine sediments.

Available macronutrients contents:
Macronutrients status of the soils is an important aspect in context of sustainable agriculture production and it play a vital role in maintaining soil health and also productivity of crops. Regarding the available N, P and K data presented in the following is a brief description.
a. Nitrogen; Data of available N show that the available contents are generally low and do not exceed 18.8% of the total contents and it tends to decrease in coarse textured soils and organic matter. Data demonstrate that the distribution of available N range between 6.58 to 33.76 mg kg -1 . As clear from Map (12), the whole study area has low contents of available nitrogen that are grouped into one class, low (<40 mg kg -1 ) and the maximum recorded value is 33.76 mg kg -1 .

b.
Phosphorus; Data of the available P values, revealed that they did not exceed 3.8% of the total content, presumably due to either adsorption on the surface of CaCO3 particles and/or precipitation due the reaction with soluble Ca that may available from the relatively high gypsum contents in the study area. This finding is consistent with the results reported by (Borhamy, 2001) as he indicated that the available content of P usually do not exceed 5% of the total content. The relatively high values of soil pH and adsorption of P on Mn and Fe oxides may also reduce P availability in the study area. As indicated in Map (13), the recorded values of available P in the study area ranged between 1.60 to 7.23 mg kg -1 and allocated in different categories; low content (<5 mg kg -1 ), and medium content (5-10 mg kg -1 ) occupied 46799.37 and 3659.67 hectare, respectively. (14) show that the available K does not exceed 4.3% of the total K contents, the values ranged between 52.24 to 367.8 mg kg -1 . However, only limited area possess medium available K values range between 200-400 mg kg -1 (2.19 % of total area), while the majority of study area possess low available K values less than 200 mg kg -1 (97.80 % of total area).

Available micronutrients contents:
There are many essential factors that may affect the contents of such micronutrients among them organic matters, soil pH, lime content, sand, silt and clay contents.

a. Iron;
Fe is largely present in soils as insoluble Fe (III) oxides and its solubility greatly affected by the redox potential. The obtained data indicated that more than 99% of the study soils possess very low to low available Fe; ranged between 1.02 to 5.56 mg kg -1 .
b. Manganese; Available amounts of Mn ranged between 0.36 to 2.19 mg kg -1 . The lowest available Mn values are associated with the coarse texture higher content of CaCO3 in similar results were obtained by (Ibrahim, 2001).However, the study area has low in available Mn content.

c. Zinc;
Available Zn values in most of the study area are very low to low, these values ranged between 0.16 to 1.33 mg kg -1 . Approx. 78.66% of the study area has very low value <0.5 mg kg -1 .

d. Copper;
The obtained data revealed that 97.85 % of the study soils possess very low to low amounts that range from 0.10 to 0.94 mg kg -1 . The lowest values attributed to the relatively coarse skeletal texture grade with low OM contents being of a very poor ability for Cu retention.

Soil classification
The purpose of soil classification is to provide basis for grouping and memorizing, to integrate knowledge of soils, to relate soils to each other and to their environments and to enable predictions of the soils behavior and response to anthropogenic intervention in its natural development. In the light of these results it could be concluded that the study area possesses two main soil Orders namely; Aridisols and Entisols covering 21168.49 and 29031.14 hectare; respectively, in addition, rock is covering 259.33 hectare.

Current land capability:
Land capability assessment is considered one of the most important outputs of soil studies. Estimation of current land capability is illustrated in Map (15). The results revealed that the studied area possesses 48102.12 hectare of capable soils with classes II, III, IV, i.e. 95.33 % of the studied area, whereas the remaining areas are of very poor capability and/or of rocky in nature. The capability of the studied area varies from "good to very poor "according to some existing limiting factors as salinity, coarse texture, gravels content, calcium carbonate content, gypsum content and shallow soil depth. Part of these limiting factors could be corrected with time as salinity and gypsum while, texture, gravels content, calcium carbonate and shallow soil depth are considered economically not correctable.

Potential land capability:
Land capability of the studied area is governed by different limiting factors. Some of these factors can be improved through appropriate soil management practices to enhance its land capability, Map (16). These management practices include leaching of salinity of some profiles where salinity leaching could drop soil salinity to 4 dS m -1 as these of profiles having coarse fraction and very deep besides they are lacking the impact of higher gypsum or calcium carbonate aggregate in their layers. While other profiles are affected by gypsum and calcium carbonate content so prediction for salt leaching is moderate. On the other hand, the presence of petrocalcic horizon sand layers with high gypsum content are expected to hinder salt leaching process in four profiles. By applying salt leaching management, the potential capability classes of the studied area are expected to be developed as Potential Class II, III, IV and V as presented in Map (16). Potential class II covers an area of approx. 6761.55 hectare (13.40% of the studied soils). This area is located in the eastern south and western south of the studied area. Potential class III covers an area of approx. 33921.13 hectare (67.22% of the studied area). Potential class IV covers an area of approx. 9303.08 (18.43% of the studied area). Very poorly potential class V covers a limited area of approx. 216.41 (0.43% of the studied area).

Land suitability for crops
Land suitability for crops is considered a very important issue in the reclamation of desert area and predicts the suitable land use in the area. Physical land suitability emphasizes the potential success of cultivating a specific crop in this area. Therefore, current and potential land suitability digital maps were produced for the studied soils. Current land suitability maps reflecting the soil suitability for selected crops under the current soil properties. While, the potential suitability is representing the crops suitability for the area after leaching salinity. Brief discussion of the tested crops is given below: (17)

GIS fertilizer requirements digital maps for the selected crops
The resulted available nutrients status maps (expressed in mg kg -1 ) were used later for the calculation of fertilizer requirements for the proposed crops according to the recommended fertilizer requirements for each specific crop. This was done by simple subtract operation between the existing nutrients contents map and the recommended quantity of fertilizers to the proposed crops. The resulted fertilizers needs digital maps could be multiplied by simple conversion factors to have maps displaying the needed fertilizers in any commercial fertilizer forms. ➢ We should pay attention to P fertilization of the reclaimed land. The estimated need for this land is approx. 714 kg/hectare in the form of superphosphate (15.5%). The spatial distribution of the needed P fertilization is exhibited in Map (33). P fertilization map shows that the maximum needed P reached 42.8 kg P/hectare, whereas the average need for the whole studied area 39.7 kg P/hectare. Most of the studied area in needs to P fertilization 38.0 40.5 kg P/hectare (32073.0 hectare).
➢ K fertilization is recommended to be added at a rate of 238 kg/hectare of potassium sulfate (48%) during servicing or with the first batch of adding nitrogen fertilizer. However, the total studied soils show adequate potassium contents for sugar beet requirements; only just bio-fertility could be utilized.
3.6.2. Fertilization maps for some summer crops.

Maize (Zea Mays L.)
➢ N fertilization needed is 952 kg/ hectare in the form of ammonium nitrate 33.5%. In three doses they should be applied the first at cultivation, the second after thinning and the third batch before the second irrigation (ARC-Ministry of Agriculture-Egypt, brochure No.962). The distribution pattern of N fertilization needs of the studied area is shown in Map (34) (37), in the studied area, approx. 34142.7 hectare (68.15%) needs approx. 23.0-25.5 kg P/hectare. The recorded average needed of phosphorus fertilization reached to 24.1 kg P/hectare.
➢ The recommended addition of potassium sulfate during the land preparation is a rate of 238 kg/hectare. The total studied soils show adequate amounts potassium for sorghum cultivation.
3.6.3. Fertilization maps for some orchard trees.

*Citrus (Citrus Spp):
The following is a proposed program to fertilize citrus trees of age 1-3 years in the reclaimed lands (ARC-Ministry of Agriculture-Egypt, brochure No.366).
➢ Trees need N fertilization is 833 kg ammonium sulfate (20.5%) per hectare, for one year, where this amount is added through 21 dosages added from the second half of February and ending June. In addition, is recommending to be added 47.6-59.5 m 2 of manure per hectare. As Map (38), illustrates the distribution pattern of N fertilization needs for the studied soils. The maximum estimated value is 155.5 kg N/hectare for year, while the average value is 141.1 kg N/hectare. A few areas approx. 1249.3 hectare of soils is needed 126.8-129.0 kg N/hectare. Whereas most of studied soils, approx. 32267.8 hectare, need fertilization at a rate ranged from 140.0-149.0 kg N/hectare for year.
➢ P fertilization at a rate of 238 kg super phosphate (15.5%) per hectare is recommended. The spatial distribution of the needed P fertilization is illustrated in Map (39). P fertilization map show that the maximum needed P reached 11.7 kg P/hectare for one year, whereas the average need for the whole studied area 8.5 kg P/hectare. Most of the studied area (13194.4 hectare). in need to P fertilization ranges 7-9.5 kg P/hectare.
➢ Recommendation for K fertilization is adding 190 kg/ hectare of potassium sulfate per year divided into two batches, the first installment in March and the second in August. However, the total studied soils show adequate potassium contents for citrus cultivation; only just bio-fertility could be applied.

Maps (38, 39): Nitrogen and phosphorus fertilizer requirements (kg N, P, /hectare) for citrus
It is worthy to mention that digital maps for micronutrients fertilizer requirements to the selected crops could be produced. But, it should be bearing in mind that it is not advisable to correct deficiency of micronutrients dominating in sandy and calcareous soils through soil addition but through foliar application.

Conclusions
The current study concluded that: Incorporation of GIS methodology could be very helpful to produce accurate digital maps for the different soil characteristics, total and available nutrients status, land capability, land suitability for crops and the adequate fertilizer recommendation requirements for them. The resulted fertilizers needs maps are considered very potential for precision farming application. Therefore, it is recommended to apply such scientific methodology, depending on the most advanced recent technology, on the other new agricultural extension areas. Furthermore, in order to achieve much more benefit of the current work or similar one, it is advisable to monitor and update the available nutrients status for the tested point (that identified by GPS).This is suggested to be done twice a year before winter and summer cultivations to retrieve updated fertilization maps. This guide could be used by the decision makers for strategic fertilization plans.