The study area is located in North of Atbara city, River Nile State, Sudan, with an altitude of (336 - 358 meters) above sea level. The study area covered about 8000 ha and is located where the coordinate is at 17.82289 to 17.82389N and 33.99974 to 34.02127E. According to [8] , the study area falls within the arid climatic zone. The average annual rainfall varies from 0 to < 100 mm. Mean maximum temperature of the hottest months (May and June) is 43˚C. Mean minimum temperature of the coldest month (January) is less than 13˚C. The mean annual relative humidity ranges between 15% to 21% (January to February), less than 15% (March to June). The predominant natural vegetation in the study area consists of the following species: Tundub (Capparis decidua), Seyal (Acacia tortilis), Usher, Musket (Prosopis chilensis), Heglig (Balanites aegypiaca) and Seder (Zizyphus spina-christi). The calculated soil temperature regime is hyperthermic and soil moisture regime is arridic. According [9] , the soils of the study area belong within Entisols and Aridisols orders.

Nine soil samples were collected from different Nile river terraces at River Nile State, North of Sudan (Table 1). At each site, approximately 5 kg of soil sample was collected from the depth of 0 - 30 cm using an auger and kept in a plastic bag. In the laboratory, soil samples were air-dried and passed through a 2 mm mesh sieve to obtain the fine earth fraction. To estimate the influence of storage period at different temperatures on the concentrations of soluble cations and anions, a 1:5 soil suspension was shaken for 30 minutes, and then extracted

with filter paper (Whatman No. 42). Each soil extract then divided into three treatments: i) control (time zero) or immediately analyzed); ii) storage for 10 days and; iii) storage for 30 days. Each treatment was replicated three times: i) storage at 10˚C; ii) storage at ambient laboratory temperature (25˚C) and; iii) storage at 45˚C in incubator.

The particle size distribution of the subsamples was determined using Particle size analyzer model (Mastersizer 2000, Malvern) and the soil texture class was determined using USDA Textural triangle [10] . Soil pH was measured in 1:5 soil suspensions using a digital pH meter Model (3510, Jenway) and the results were compared according to the classification of [11] . The electrical conductivity (EC dS/m at 25˚C) was determined in 1:5 soil extract using a conductivity meter Model (4510, Jenway) [12] and the results were compared according to the classification of [13] . Percent calcium carbonate (%CaCO₃) was estimated by Calcimeter. The samples were treated with 0.1N HCL; the volume of CO₂ from pure calcium carbonate and samples were recorded. The percent calcium carbonate was then calculated according to [14] . Extractable cations (Ca²⁺, Mg²⁺, Na⁺ and K⁺) and anions (Cl⁻, and) were determined in 1:5 soil extraction.

Changes during storage period at 10 and 30 days were determined by repeated measures analysis of variance using storage period and treatment (10˚C, 25˚C and 40˚C) as factors. Values for fresh extracts (control) were compared with those from extracts stored for 10 and 30 days by one-way analysis of variance with Turkey’s significant difference test for mean separation (P < 0.05). All statistical analysis was performed using SPSS software version 16.0 (SPSS Inc, USA).

The description of the samples sites in the study area and some of the physical and chemical properties are presented in Table 1 and Table 2 respectively. The soil texture ranged from sandy loam in the first terrace, silt loam in the second terrace (Instructional farm). While the soil texture in the Agricultural College farm was sand. This could be due to the fact that these soils falls in the mining area which are truncated soils. The soils of the study area were moderately calcareous and the %CaCO₃ ranged from 2.58% to 7.40%. The soil reaction (Soil pH) varied from alkaline to strongly alkaline with a pH value ranged from 7.46 to 8.80 [11] . According to [13] , the soils of the study area were non-saline and the electrical conductivity (EC_e) ranged from 0.22 to 0.57 dS/m. The predominant soluble cations and anions in the study area were (Na⁺ and Ca⁺⁺), (and Cl⁻) respectively.

Comparing first and second storage period there were significant difference at P < 0.05 found in all estimated cations (Table 3 and Figure 1) respectively, except for Na⁺ and K⁺. The Ca²⁺ and Mg²⁺ concentrations were significantly increased from11.22 ± 1.978^a to 17.503 ± 4.047^b and from 3.790 ± 2.794^a - 5.568 ± 3.722^b respectively. Similar trend were found when comparing 10 days with 30 days storage period, Ca²⁺ and Mg²⁺ concentrations were significantly increased from 17.503 ± 4.047^b to 23.505 ± 5.998^c in addition to K⁺ concentration

Means in each row with different letters are significantly different at P < 0.05.

which increased from 3.582 ± 1.306^a to 3.968 ± 1.430^b. These obtained results were expected specially increasing the storage period logically content in soluble solution. When we compared first and third storage period there were significant difference found in K⁺ and highly significant difference observed in Mg²⁺ (from 3.790 ± 2.794^a to 7.334 ± 4.739^c) and Ca⁺⁺ (from 11.22 ± 1.978^a to 23.505 ± 5.998^c) at P < 0.05 level. [15] reported that extractable Ca²⁺, K⁺, and Mg²⁺ were less influenced by storage period, although the effects varied among soil types.

In anions part (Table 4 and Figure 2) respectively, while comparing first and second period results shown that Cl⁻ and concentrations were significantly increased from0.318 ± 3.553^a to 0.749 ± 1.498^b and 0.808 ± 3.550^a to 0.885 ± 5.710^b respectively. However, concentrations were highly significant decreased (from 12.67 ± 2.158^a to 3.577 ± 3.186^c) with increased of storage period. Similar results were obtained by [15] . Contrasting, [16] reported that soil storage before separation of the soil solution by centrifugation caused a marked decline in P concentrations.

Comparing first and second temperature (10˚C and 25˚C), significant different were found in Mg²⁺ and Ca²⁺

*Means in each row with different letters are significantly different at P < 0.05.

from 3.790 ± 1.452^a to 5.568 ± 1.934^b and 11.22 ± 1.028^a to 17.503 ± 2.103^b respectively. Similarly significant different are found while comparing K⁺ in second and third temperature (25˚C and 45˚C), and highly significant different were found while comparing second and third temperature in Mg²⁺ and Ca²⁺ respectively (Table 5 and Figure 3). Similar results were obtained by [15] . Additionally, change in K⁺ and Ca²⁺ concentrations during low temperature storage were observed to be less significant and associated with soil types [17] .

Comparing first and second temperature (10˚C and 25˚C), significant different were found in Cl⁻ and from 0.318 ± 0.185^a to 0.749 ± 0.779^b and 0.808 ± 1.844^a to 0.885 ± 2.967^b respectively. [14] , in their study reported that, extractable PO₄ of Refrigerated samples always contained lower values than counterparts stored at

room temperature. They also pointed out that, extractable were significantly differences among the soil types. Moreover, the amounts of extractable were significantly increased during low temperature storage [15] . In contrast, [17] , reported that soil storage before separation of the soil solution by centrifugation caused a marked decline in P concentrations, including those of molybdate-reactive P and dissolved organic P, within a few days. However, concentrations were significantly influenced by increased temperature (Table 6 and Figure 4).