الفهرس 
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Abstract
”Fertility Assessment Of Some Soils at Nile Delta, Egypt Using GIS techniques .Evaluation of soil fertility of alluvial soils in the Nile-Delta of Egypt is very important, especially after decades of intensive cropping and loss of silt-deposits after building the High Dam in the 1960s. Accordingly, the main objectives of this study were to evaluate of soil fertility of some soils in Gharbia Governorate and their suitability for some strategic crops through using GIS techniques. This study was carried out at the Samannoud district, Gharbia Governorate, Egypt. Studied area is located between these longitudes 30°03’46”” and 30°00””N, and longitudes 31°20’03”” and 31°08’10”” E. It covers an area of about 166.2 km2 Accordingly, 17 georeferenced soil profiles were randomly distributed within the studied area. Soil samples were collected from each profile at 0-30 and 30-60 cm soil depth interval. Collected soil samples were analyzed for their physical, chemical, and fertility properties. Water samples were also collected from irrigation canals close to each soil profile. These water samples were analyzed for their chemical properties. Evaluation of soil fertility and suitability for some crops production was performed using the Agriculture Land Evaluation System (ASLE). Soils in the studied area were classified into two classes (fair and poor) according to fertility index. Land suitability for the selected crops varied from very suitable to currently unsuitable. The limitations for crop productivity in the studied area can be alleviated through using proper fertility and land management practices. Data in display the results of soil physical properties (Particle size distribution, texture classes, saturation percentage and bulk density) in the thoughtful soil profiles. Particle size distribution contain: coarse sand, fine sand, total sand, silt and clay. Coarse sand in the study areas ranged between 0.13 and 13.10 %. Fine sand varied from 9.4 and 57.8%. Total sand (TS) ranged between 9.5 and 58.0% . Silt percentage ranged between 7.0 and 49.7% . Clay percentage varied from 26.8 to 48.2%. Accordingly, the majority of soil textures in the studied area were Clay. Saturation percentage (SP) ranged between 48.3 and 88.8 % (about 76.3% on average). SP values were associated with higher clay content in the deliberate soils. The bulk density (BD) values were low and diverse from 0.91 to 1.18 g cm-3 (1.06 g cm-3 in average), which is example to fine-textured soils. Data display some soil chemical properties of the studied soil. These properties contain soluble cations (Ca2+, Mg2+, K+ and Na+) and anions (CO32-, HCO3-, Cl- and SO42-), pH, and electrical conductivity (EC). Calcium ions (Ca2+) various from 0.38 and 2.70 cmol/kg soil (about 1.00 cmol/kg in average). Magnesium ions (Mg2+) ranged between 0.17 and 2.81 cmol/kg soil (about 0.71cmol/kg in average). Potassium ions (K+) various from 0.04 and 0.43 cmol/kg soil (about 0.15 cmol/kg in average). Sodium ions (Na+) ranged between 0.01 and 0.77 cmol/kg soil (about 0.20 cmol/kg in average). Carbonates ions (CO32-) were null in soil extracts of the studied soil samples. Bicarbonate ions (HCO3-) various from 0.43 and 1.62 cmol/kg soil (about 0.82 cmolkg-1 i in average). Chloride ions (Cl-) ranged between 0.11 and 1.64 cmol/kg soil (about 0.64 cmolkg-1 in average). Sulfate ions (SO42-) various from 0.03 and 4.46 cmol/kg soil (about 0.99 cmolkg-1 in average). Soil pH ranged between 7.97 and 9.40 (about 8.53 in average). Electrical conductivity (EC) various from 0.29 and 2.37 dSm-1 (about 0.69 dSm-1 in average). This indicates that the studied soils are non-saline, which could be contributed to the good management practices in the studied area. Data display the values of exchangeable cations, cation exchange capacity (CEC), and exchangeable sodium percentage (ESP). Exchangeable Na+ various from 0.06 and 1.64 cmol/kg soil. Exchangeable K+ ranged between 0.15 and 2.04 cmol/kg soil. Exchangeable Ca2+ various from 33.90 and 70.13 cmol/kg soil. Exchangeable Mg2+ ranged between 8.22 and 38.78 cmol/kg soil . The CEC values various from 45.56 and 88.27 cmol/kg soil (about 77.67 cmol/kg soil in average). the ESP values ranged between 0.13 and 2.25 % soil (about 1.16 % in average). This indicates that the studied soils were non-sodic soils. Data display the values of available NPK, total nitrogen (TN), organic matter (OM) and C/N ratio in the studied soil samples. Available (N) ranged between 30.73 and 100.25 mg/kg soil (about 57.17 mg/kg soil in average). Available (P) various from 2.37 and 13.47 mg/kg soil (about 5.38 mg/kg soil in average). This indicates a lower phosphorous content. This also indicates that soils in the studied area are in need to fertilization with phosphorus fertilizers. Available (K) ranged between 95.88 and 957.88 mg/kg soil (about 347.57 mg/kg in average). Organic matter (OM) ranged between 0.26 and 2.20 % (about 1.11 % in average). Total (N) varied from 0.03 and 0.10 %, which indicates a very low content. The C/N ratio varied from 2.31 and 11.03, which indicates that nitrogen mineralization is the dominant process . Data is display of some chemical characteristics of the irrigation water in the studied area. A the analysis reveals that the irrigation water is non-saline where the EC was 0.59 dS m-1. The pH of the irrigation water was 7.5. The irrigation water used was non sodic where the SAR values were 0.07 dS m-1. Concerning the contents of soluble cations in irrigation water (Ca+2, Mg+2, Na+ and K+) were 4.4, 2.8, 0.11 and 0.17 meq L-1, respectively.. Concerning the values of soluble anions content in respective irrigation water used : CO=3 ions are absent. The HCO-3 anions content was 4.09 meq L-1. Values of Cl- and SO=4 were 2.51 and 0.88 meq L-1 respectively. The following indicators are explained Clay Index, OM Index, available NPK Index and fertility indices of the studied soils. According to the clay index ranged between 80.69 and 99.83 (about 92.61 in average). OM index in the studied soils ranged between 5.66 and 31.25 (about 18.56 in average). Avai_N index in the studied soils ranged between 18.49 and 62.68 (about 35.35 in average). Avai_P index ranged between 11.17 and 33.21 (about 17.53in average). Avai_P index ranged between 11.17 and 33.21 (about 17.53in average). Avai_K index ranged between 58.32 and 100.00 (about 90.09 in average). Fertility index ranged between 37.25 and 55.73 (about 45.20 in average). The fertility index was fit into two classes, which are poor and fair . data indicate that soils in the studied area were very suitable (S1) for Wheat . While were fit into two classes, which are very suitable (S1) and suitable (S2) for Maize . Also, were fit into three classes, which are very suitable (S1), suitable (S2) and currently unsuitable (N1) for Faba Bean . While were fit into two classes, which are S3= moderately suitable and S4= marginally suitable for Rice. The obtained results revealed that the majority of soils in the studied area were clayey in texture, which had an obvious impact on the soil physical properties such as the saturation percentage (SP), bulk density (BD) and total porosity. The average values of SP, BD, and total porosity were about 71%, 1.08 g cm-1, and 59%; respectively. The content soil organic matter was very low in the studied soils, where it ranged between 0.19 and 1.43% (about of 0.67% in average). Calcium carbonates were relatively in the studied soils and they varied from 0.55 to 10.40% (about 3.07% in average). Chemical properties of the studied soils revealed that sodium was the dominant cation in the soil solution followed by calcium, magnesium and potassium ions. Their average concentrations were about 0.93, 0.22, 0.19 and 0.01 meq/100 g soil, respectively. In the contrary, chlorides were the dominant anions followed by sulfates and bicarbonates. Their average values were about 0.81, 0.34, and 0.20 meq/100 g soil; respectively. Soil pH varied from 7.64 to 8.24 with an average of 7.95. Soils in the studied area were non-salinity, where the EC values varied from 0.41 to 4.65 dS m-1 with an average value of 1.88 dS m-1. The values of cation exchange capacity (CEC) were high as affected by the fine soil-texture. They varied from 40.61 to 58.87 meq/100 g soil (about 51 meq/ 100 g soil in average). The exchangeable sodium percentage (ESP) ranged between 1.90 and 11.10% (about 4.17% in average); which indicates that the studied soils were non-sodic. The average values of available NPK were about 124, 5.40, and 310 ppm; respectively. These results indicate lower contents of available phosphorous. Total nitrogen content was about 0.26% in average and organic carbon was very low (about 0.47% in average). Consequently, the C/N ratio ranged between 1:1 and 5:1, with an average of 2:1. Soil fertility evaluation using GIS models and techniques could be very helpful in providing more accurate and time-wise information about the status of soil fertility within certain area. Soils in the studied area . In conclusion, the limitations for crop productivity in the studied area were not permanent and they can be improved through proper fertility and land management practices.