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Speciation of heavy metals exerts important controls on chemical behavior, solubility, toxicity, adsorption and even physical properties of solutions (Ure and Davidson 2002). In the present study, speciation and mineral-solid phase of Cd, Ni, and Pb in solution of soil prolonged irrigated with sewage effluent were predicted using GEOCHEM model (Sposito and Mattigod (1980) and constructed stability diagrams (Sposito ,1989 andLindsay ,1979).The present data indicate that total contents of all tested metals have increased dramatically as a result of sludge amending, particularly, for Cd. In virgin soil solution, the results of speciation indicated that, free species M 2+ was the prevalent form (60.35%) followed by carbonate species MCO 3 aq (20.12%), MSO 4 (5.93%), MHCO 3 + (5.56%), MOH + (4.21%) and MCL + (4.21%), while in sludge -soil solution the sequence was; M-DOC (41.92%), followed by MHPO 4 species (26.74%), M 2+ ( 20.07%) , MHCO3 + (4.22%), MSO 4 aq (3.49%) and MCO 3 aq (2.02%). It is clear from the results that amending soil with sludge decreases active portion (M +2 ) contribution to total speciation of the tested metals. In virgin soil, the majority of both Cd and Ni was (M +2 ) species. It amounted (79.03%) and (83.8%) , respectively . While MCO 3 aq was the prominent for pb (55.86%). In sludgesoil, Pb was almost exclusively in organically complexed forms (88.54%), while the majority species of Ni was M +2 (38.56%) and for Cd, CdHPO 4aq (58.72%). The data also showed that in sludge-soil the activities (Ml -1 ) of both Pb and Ni decreased by 26% and 72%, respectively, compared to their corresponding values in virgin soil. Meanwhile, the activity of Cd increased. These findings suggesting that amending soil with sludge probably inhibit activities of some metals, while promote activity of others. The data showed that the values of activities of Cd in virgin soil was closed to the solubility of CdCO 3 (log CO 2 =-2.52) and CdSO 4 -2Cd (OH) 2 at (log So 4 =-2) , while in sludge soil ,the value of Cd +2 was under saturated with respect the constructed Cd-minerals. This suggested that other possible solid phase of cadmium may be controlling its activity in that soil .Also , the data suggested that activity of Ni +2 in virgin soil is governed by Ni 3 (PO 4 ) 2 in equilibrium by gypsite. While in sludge-soil, value of Ni +2 was controlled by Ni 3 (PO 4 ) 2 in equilibrium with Caphosphate mineral at (log CO 2 = -4.52). Also, the results indicated that Pb 3 (CO 3 ) 2 (OH) 2 was the possible solid phase which may be controlled the activity of Pb +2 , in both virgin and sludge soil.

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Twelve soil profiles representing North-West of Dashlut area, Assiut, Egypt were selected and dug, and 43 soil samples were collected from these profiles to evaluate its productive capability and suitability for growing selected crops. The soils of this area had a coarse texture grades (sand, loamy sand, and sandy loam). Most of these soils were highly saline (ECe > 16 dS/m) and showed low values of organic matter and available NPK, some of these soils are considered as calcareous. Tow modern programs including the applied system of land evaluation (ASLE) and the microcomputer land evaluation information system (MicroLEIS) were applied to assess the capability of these soils and their suitability to grow selected crops. The results of land capability showed that the soils of the study area were poor (C4), very poor (C5), and non-agricultural (C6) using the ASLE program, while the MicroLEIS (Cervatana model) program pointed that soils had moderately (S3) and marginally (N1) capable grades. Moreover, using the ASLE program, the soils of the study area were highly suitable, suitable, moderately suitable, marginally suitable, and currently not suitable and permanently not suitable for 28 field and vegetable crops and fruits. The land suitability using MicroLEIS (Almagra model) program indicated that the soils of this area were moderately suitable, marginally suitable, and non-suitable for the selected crops due to one or more of the limiting factors. The geostatistics approach performed with ordinary kriging interpolation and semivariogram was applied to create a detailed and spatialized map for each soil parameter. Circular, J-Bessel, J-Bessel, and Stable geostatistical models were used to define the spatial variability of soil parameters based on RMS, MSE, and RMSSE. The main soil limitations of these soils were soil texture, soil salinity, and low soil fertility. However, these soil limitations are none permanent and can be improved through applying suited management practices.

The pot experiment was conducted in summer season of 2017 at Assiut Governorate, Egypt, to study the influence of compost and different rates of inorganic nitrogen on growth and chemical composition roselle as well as yield. The studied treatments include the application of recommended dose of N as T 1 = urea, T 2 = compost, T 3 = 75% urea + 25 % compost and T 4 = 50% urea +50% compost. Plants treated with the combination of mineral nitrogen and organic fertilization gave the highest significant values of growth parameters, i.e., plant height, as well as fresh and dry weight of leaves, chlorophyll, carotenoids, N, P and K contents in leaves tissues. While the application of full dose in the inorganic form gave the moderate values compared to the untreated plant. The maximum sepals yield was obtained from the 100% of N from compost treatment which increased the fresh and dry weight of sepals by 228.75 and 138.96% above the untreated soil. Generally it is concluded that roselle sepals yield and quality can be improved through the treatment of 100% composted and application of 50 % urea + 50 % compost improved the growth and yield of roselle also increased the available N nutrients in the soil as well as the macronutrients concentrations. Therefore, this treatment could be recommended to obtain economical yield with satisfactory quality and to improve the soil fertility under the conditions of the studied area.