Thirty surface and subsurface soil samples were collected from 15 sites of El- Dakhla soils, Egypt to study the status of soil potassium forms and their relationship with the physical and chemical properties of these soils. The results indicated that the investigated soil samples showed a wide variation in soil potassium forms. This variation depended upon clay, silt and sand contents as well as soil properties. The soluble K form values ranged from 4.7 to 1332 mg/kg and the exchangeable K form differed from 5.37 to 1368.80 mg/kg. However, the non-exchangeable K form varied from 0.3 to 4.2 g/kg and the total K varied from 2.3 to 19.89 g/kg. The residual K extended from 0.9 to 17.4 g/kg. Generally, about 16.66 % of studied samples were very low in the exchangeable K form. The samples which had a moderate exchangeable K content represented 13.33% of the investigated samples. Also, about 20% of these samples were high in their content of exchangeable K. The very high exchangeable K content represented 40% of the investigated samples. The ECe value had no respectable effects on the soluble K form but, a slight effect was observed in the other K forms. This effect increased in the residual K form. The OM content more than 1% had no remarkable effects on the soluble or exchangeable K forms. However, a clear effect was observed on the residual K form. Generally, all potassium forms had highly significant positive correlations with each other and with organic matter and pH. Also, all forms except the soluble K form showed highly significant negative correlations with calcium carbonates and sand content.

In Garb El-Mawhob area, northwest of El-Dakhla Oasis, New Valley governorate, Egypt, nine transects (≈ 5km away between two consecutive ones) containing 17 soil sites were designated to evaluate the available potassium (K)and its relation with some soil properties. Surface (0-30) and subsurface (30-60) soil samples were collected from each profile, air-dried, ground, sieved and then, kept for some physical and chemical analyses. The obtained results indicated that about 56, 65 and 41% of the total soil samples contained sand, silt and clay respectively of more than 60, 10 and 30%, respectively. The saturation percentage (SP) varied from 25 to 110% and increased whenever the clay or organic matter content increased. The organic matter content differed from 0.01 to 2.48 % and decreased with soil depth. The CaCO3 content of these soils varied from 2.20 to 59.24%. The pH values ranged from 7.44 to 8.03.The electrical conductivity of the soil paste extract (ECe) differed from 0.71 to 171.30 dS/ m with an average value of 20.33dS/ m. The soluble anions could be arranged in the descending order of Cl> SO4 > HCO3. The soluble cations could be arranged in the descending order of Na >Ca> Mg > K . The sodium adsorption ratio of the soil paste extract (SARe) ranged from 0.31 to 85.20. Cation exchange capacity (CEC) values ranged from 6.58 to 62.56 cmol(+)/ kg with a mean value of 29.44 cmol(+)/ kg and it increased with soil depth. The available K ranged from 148.98 to 944.12 mg/ kg with an average value of 451.81 mg/ kg. About 47.06% of the studied soil samples contained a very high level of available K (> 450 mg/ kg),20.56% had a high K level (251- 450 mg/ kg), 29.41% showed a moderate K level (151-250 mg/kg) and only 2.94% exhibited a low K level (86-150 mg/ kg). The available K was found to be positively correlated to silt content, clay content, SP, ECe, SARe and CEC as well as soluble Na, Mg, HCO3 and SO4. However, it was negatively correlated to both sand and CaCO3 contents.

In Garb El-Mawhob area, northwest of El-Dakhla Oasis, New Valley governorate, Egypt, nine transects (≈ 5km away between two consecutive ones) containing 17 soil sites were designated to evaluate the available potassium (K)and its relation with some soil properties. Surface (0-30) and subsurface (30-60) soil samples were collected from each profile, air-dried, ground, sieved and then, kept for some physical and chemical analyses. The obtained results indicated that about 56, 65 and 41% of the total soil samples contained sand, silt and clay respectively of more than 60, 10 and 30%, respectively. The saturation percentage (SP) varied from 25 to 110% and increased whenever the clay or organic matter content increased. The organic matter content differed from 0.01 to 2.48 % and decreased with soil depth. The CaCO3 content of these soils varied from 2.20 to 59.24%. The pH values ranged from 7.44 to 8.03.The electrical conductivity of the soil paste extract (ECe) differed from 0.71 to 171.30 dS/ m with an average value of 20.33dS/ m. The soluble anions could be arranged in the descending order of Cl> SO4 > HCO3. The soluble cations could be arranged in the descending order of Na >Ca> Mg > K . The sodium adsorption ratio of the soil paste extract (SARe) ranged from 0.31 to 85.20. Cation exchange capacity (CEC) values ranged from 6.58 to 62.56 cmol(+)/ kg with a mean value of 29.44 cmol(+)/ kg and it increased with soil depth. The available K ranged from 148.98 to 944.12 mg/ kg with an average value of 451.81 mg/ kg. About 47.06% of the studied soil samples contained a very high level of available K (> 450 mg/ kg),20.56% had a high K level (251- 450 mg/ kg), 29.41% showed a moderate K level (151-250 mg/kg) and only 2.94% exhibited a low K level (86-150 mg/ kg). The available K was found to be positively correlated to silt content, clay content, SP, ECe, SARe and CEC as well as soluble Na, Mg, HCO3 and SO4. However, it was negatively correlated to both sand and CaCO3 contents.

IRRIGATION of forests with sewage water for fuel and timber production in Egypt is an approach which helps to overcome health hazards associated with sewage farming. Hopefully, sewage water will help in the expansion of the irrigated agriculture or save the fresh water for other sectors. This study was carried out to investigate the impact of irrigation with treated sewage water on the properties and nutrients status of soils in Luxor Governorate. samples of sewage water, ground water and Nile water as well as samples of soil irrigated with these water sources were collected and analyzed. The results showed that sewage water and groundwater are considered moderately saline with an ECw of 0.88 and 1.20 dS/m, respectively, while the Nile water is slightly saline (ECw 0.27 dS/m). With respect of their SAR, RSC and Cl values, all investigated water sources are of a high quality and can be used in the irrigation without limitations. Moreover, sewage water contained higher amount of organic matter, N, P and K compared to groundwater and Nile water. On the other hand, most of the soils that were irrigated with sewage water were of low levels of salinity (ECe 4dS/m) and sodocity (SARe 13), indicating no threat to soil quality. Use of sewage water in irrigation also improved the chemical properties and fertility status of the soils. It increased OM, N, K and P levels in the soils while pH and CaCO3 values decreased. The irrigation system showed effects of treated sewage water on the soil properties. The soils irrigated with sewage water under the surface irrigation system had higher values of OM, ECe, total nitrogen and available phosphorus but lower SARe and available K levels than those under the drip irrigation systems. Moreover, prolonged irrigated (15 years) with sewage water had a higher values of saturation percentage, organic matter, total nitrogen, available phosphorus, and available K but the lower ones of pH, SARe and calcium carbonate than those under the short term (4 years) use of sewage water.

IRRIGATION of forests with sewage water for fuel and timber production in Egypt is an approach which helps to overcome health hazards associated with sewage farming. Hopefully, sewage water will help in the expansion of the irrigated agriculture or save the fresh water for other sectors. This study was carried out to investigate the impact of irrigation with treated sewage water on the properties and nutrients status of soils in Luxor Governorate. samples of sewage water, ground water and Nile water as well as samples of soil irrigated with these water sources were collected and analyzed. The results showed that sewage water and groundwater are considered moderately saline with an ECw of 0.88 and 1.20 dS/m, respectively, while the Nile water is slightly saline (ECw 0.27 dS/m). With respect of their SAR, RSC and Cl values, all investigated water sources are of a high quality and can be used in the irrigation without limitations. Moreover, sewage water contained higher amount of organic matter, N, P and K compared to groundwater and Nile water. On the other hand, most of the soils that were irrigated with sewage water were of low levels of salinity (ECe 4dS/m) and sodocity (SARe 13), indicating no threat to soil quality. Use of sewage water in irrigation also improved the chemical properties and fertility status of the soils. It increased OM, N, K and P levels in the soils while pH and CaCO3 values decreased. The irrigation system showed effects of treated sewage water on the soil properties. The soils irrigated with sewage water under the surface irrigation system had higher values of OM, ECe, total nitrogen and available phosphorus but lower SARe and available K levels than those under the drip irrigation systems. Moreover, prolonged irrigated (15 years) with sewage water had a higher values of saturation percentage, organic matter, total nitrogen, available phosphorus, and available K but the lower ones of pH, SARe and calcium carbonate than those under the short term (4 years) use of sewage water.

Nine surface (0-30 cm) soil samples were collected based on their salinity levels fromEl-Dakhla oasis, New Valley, Egypt to investigate the effect of soil salinity level on phosphorus (P) forms. The soil samples were divided into two levels based on their content of soil salinity to non-saline samples (ECe4dS/m) and saline ones (ECe>4 dS/m). Seven fractions of soil P (resin-P, NaHCO3-Pi, NaHCO3-Po, NaOH-Pi, NaOH-Po, HCl-P and Residual-P) were sequentially extracted from each soil sample using the modified Hedley method. The results indicated that relative to the total P, the mean percentages of resin-P, NaHCO3-Pi, NaOH-Pi, NaOH-Po and residual-P fractions were higher in the saline soil samples (ECe>4 dS/m) than those of the non-saline ones(ECe4dS/m). On the other side, the mean level of HCl-P fraction was lower in the saline soil samples. So, soil salinity tends to motivate levels of labile P (resin-P, NaHCO3-Pi, NaHCO3-Po), NaOH-Po and residual-P to increase on the charge of reducing the HCl-P level. Significant positive correlations were recorded between the NaHCO3-Pi, NaOH-Pi and NaOH-Po fractions and the ECe, Ca+2, Mg+2, Na+, HCO3-,Cl-, SO4-2 and SARe of these soil samples.However,the NaHCO3-Po, HCl-P and residual P fractions were negatively correlated to the ECe, Na+, Cl- and SARe.

Nine surface (0-30 cm) soil samples were collected based on their salinity levels fromEl-Dakhla oasis, New Valley, Egypt to investigate the effect of soil salinity level on phosphorus (P) forms. The soil samples were divided into two levels based on their content of soil salinity to non-saline samples (ECe4dS/m) and saline ones (ECe>4 dS/m). Seven fractions of soil P (resin-P, NaHCO3-Pi, NaHCO3-Po, NaOH-Pi, NaOH-Po, HCl-P and Residual-P) were sequentially extracted from each soil sample using the modified Hedley method. The results indicated that relative to the total P, the mean percentages of resin-P, NaHCO3-Pi, NaOH-Pi, NaOH-Po and residual-P fractions were higher in the saline soil samples (ECe>4 dS/m) than those of the non-saline ones(ECe4dS/m). On the other side, the mean level of HCl-P fraction was lower in the saline soil samples. So, soil salinity tends to motivate levels of labile P (resin-P, NaHCO3-Pi, NaHCO3-Po), NaOH-Po and residual-P to increase on the charge of reducing the HCl-P level. Significant positive correlations were recorded between the NaHCO3-Pi, NaOH-Pi and NaOH-Po fractions and the ECe, Ca+2, Mg+2, Na+, HCO3-,Cl-, SO4-2 and SARe of these soil samples.However,the NaHCO3-Po, HCl-P and residual P fractions were negatively correlated to the ECe, Na+, Cl- and SARe.

Nine surface (0-30 cm) soil samples were collected based on their salinity levels fromEl-Dakhla oasis, New Valley, Egypt to investigate the effect of soil salinity level on phosphorus (P) forms. The soil samples were divided into two levels based on their content of soil salinity to non-saline samples (ECe4dS/m) and saline ones (ECe>4 dS/m). Seven fractions of soil P (resin-P, NaHCO3-Pi, NaHCO3-Po, NaOH-Pi, NaOH-Po, HCl-P and Residual-P) were sequentially extracted from each soil sample using the modified Hedley method. The results indicated that relative to the total P, the mean percentages of resin-P, NaHCO3-Pi, NaOH-Pi, NaOH-Po and residual-P fractions were higher in the saline soil samples (ECe>4 dS/m) than those of the non-saline ones(ECe4dS/m). On the other side, the mean level of HCl-P fraction was lower in the saline soil samples. So, soil salinity tends to motivate levels of labile P (resin-P, NaHCO3-Pi, NaHCO3-Po), NaOH-Po and residual-P to increase on the charge of reducing the HCl-P level. Significant positive correlations were recorded between the NaHCO3-Pi, NaOH-Pi and NaOH-Po fractions and the ECe, Ca+2, Mg+2, Na+, HCO3-,Cl-, SO4-2 and SARe of these soil samples.However,the NaHCO3-Po, HCl-P and residual P fractions were negatively correlated to the ECe, Na+, Cl- and SARe.

Remediation ofmetal polluted sites by traditional, physical and chemicalmethods demands large investments of 19 economic and technological resources compared to green remediation.Halophytic plants have been suggested to 20 be more effective in the phytoextraction of metals from the contaminated soils compared to salt-sensitive crop 21 plants. Pot experiment was conducted to study the accumulation of cadmium (Cd) by the A. lentiformis plants 22 when treated with different rates of nitrogen fertilizer. Nitrogen was applied to the soil at rate of 0, 100, 200, 23 300 and 400 mg kg−1. Increasing the level of nitrogen from 0 to 400 mg N kg−1 increased the dry biomass of 24 roots and shoots of the studied plant by 75 and 27.5%, respectively. The application of N increased the chlorophyll 25 by 100% and leaf area index by 50% and this lead to increase in the photosynthesis and plant growth. The 26 A. lentiformis plants tolerate the high levels of Cd in the soil and plant tissues. Under metal stress conditions, 27 the studied plant contained large amount of organic compounds e.g., oxalic acid, proline and phenols. These or- 28 ganic compounds had negative effect on the plant growth and Cd accumulation in the aboveground parts of the 29 plant.When 400 mg N kg−1 was added, the chlorophyll increased by 100% and the proline, phenols and oxalic 30 acid decreased by 33, 50 and 30%, respectively compared to the control treatment. The fertilization of 31 A. lentiformis plants with the highest rate of nitrogen enabled the plants to remove 7.93% of the total soil Cd dur- 32 ing a period of 105 days. Nitrogenmitigated the effect ofmetal stress and increased the accumulation of Cd in the 33 aboveground parts of A. lentiformis plants. The fertilization of A. lentiformiswith nitrogen could be an effective tool 34 to enhance Cd-phytoextraction from polluted sites.

Nowadays, using sewage wastewater in the irrigated agriculture causes hazardous environment impacts. Assessment of these negative effects is vital issue to prevent heavy metals to be introduced in the food chain. Field and laboratory studies were conducted at Ellwan, Mangabad and El-Madabegh villages, Assiut Governorate, in order to evaluate heavy metals concentrations in the edible parts of carrot, turnip and onion plantswhich were irrigated with sewage water (SW). The obtained results indicated that, the soils of the studied villages were contaminated by heavy metals. The concentrations of Zn, Cu, Pb, Cd and Ni concentrations in the edible portion of thesevegetables plants ranged between 45-70, 13- 19, 3.8-6.2, 2.85-3.85 and 2-6 mgkg–1, respectively. The obtained results showed that the concentrations of Pb, Cd and Ni in the edible plants were higher than the permissible limit levels but those of Zn and Cu were within the safe limit levels. It is worthy to mention that the irrigated edible vegetable crops especially onion, turnip and carrot with SW should be avoided. This study highlights the potential hazard for human health due to uptake of high concentrations of heavy metals especially Ni, Cd and Pb by the studied vegetable crops.