الفهرس 
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Abstract
A pot experiment was carried out in the greenhouse of Soils and Water Dept., Fac. of Agric., Assiut Univ., Assuit Governorate in order to investigate the fate of the application of the chemical phosphate fertilizers (mono-calcium phosphate, MCP, and mono-ammonium phosphate, MAP) in the soil under salinity condition effects. Each pot (28 cm diameter and 35 cm height with holes in the bottom) was filled by 14 kg of two different soils that were sieved through a 2 mm sieve. One of the soil was brought from El-Sharif Sons farm, El-Qusia district, and the other soil was brought from a farm in Arab El-Awamer village, Abnob district. Each pot was treated with the recommended dose (RD) of nitrogen and potassium fertilizers (200 kg/ fed. of NH4SO4 and 50 kg K2SO4/ fed.) that mixed well with the soil before cultivation. Two types of phosphorus fertilizers (mono-ammonium phosphate, (NH4)(H2PO4), and mono-calcium phosphate, Ca(H2PO4)2.H2O) at three levels (100%RD, 125% RD, and 75% RD) were utilized. Each experiment consisted of two phosphorus fertilizers types, three application levels, and a control treatment (without fertilization) with three replications (a total of 21 pots). The experimental treatments for each soil type were as follows: -
- 75% of the RD from mono-calcium phosphate (75% MCP)
- 100% of the recommended dose (RD) of mono-calcium phosphate (100% MCP)
- 125% of the RD from mono-calcium phosphate (125% MCP)
- 75% of the RD from mono-ammonium phosphate (75% MAP)
- 100% of the recommended dose (RD) of mono-ammonium phosphate (100% MAP)
- 125% of the RD from mono-ammonium phosphate (125% MAP)
- Control treatment without phosphorus fertilization
In each pot, ten barley seeds (Giza 128 obtained from Agric. Res. Centre) were sown on 17th November 2016 and they were cut 60 days later (January 15st, 2017). Soil samples at two depths (0- 10 and 10- 20 cm) were taken from each pot and were subjected to different chemical analyses. The obtained results could be summarized as follow: -
1. Effect of Phosphate Fertilizer Type and Level on Some Soil Properties
1.1. Arab El-awamer soil
- Soil pH increased with soil depth for all phosphorus fertilization treatments. It changed from mildly alkaline to alkaline soil pH. Adding MCP and MAP caused a slight reduction in soil pH. The soil pH values changed from 7.76 to 8.05 for all phosphorus fertilization treatments. The 75% MAP treatment realized the least soil pH values since they were 7.76 and 7.84 at the surface and subsurface layer, respectively.
- The soil salinity (ECe) varied from 1.00 to 2.20 dS/ m with an average value of 1.39 dS/ m and it increased with soil depth. The soil ECe value increased as a result of applying phosphorus fertilizer type and level and it was more pronounced in the subsurface layer than that in the surface one. The soil ECe values did not exceed the threshold limit since they were less than 4 ds/m. The maximum increase in soil salinity of the surface layer was noticed by adding MAP since it increased by 80%. The maximum increase in the soil salinity of the subsurface layer was noticed by applying 125% MCP since it increased by 58%. The soil EC values using MCP treatments were less than those of MAP ones.
- The bicarbonate concentrations ranged from 3.20 to 6.41 mmol/kg with an average value of 4.81 mmol/kg and it increased with soil depth. The highest value (6.41 mmol/kg) was noticed with the MAP application while the lowest one was recorded for the control treatment. The chloride ion concentrations extended from 0.97 to 5.34 mmol/kg with an average value of 3.16 mmol/kg and they displayed an irregular trend with soil depth. The soluble sulfate ions differed from 1.95 to 9.03 mmol/kg with an average value of 5.49 mmol/kg and it increased with soil depth. The soluble anions in the saturated soil–paste extract of the tested soil could be arranged in the descending order of SO42- > HCO3- > Cl-. The soluble calcium ions ranged from 1.28 to 3.72 mmol/kg with an average value of 2.50 mmol/kg and it increased with soil depth. The soluble magnesium varied from 2.11 to 5.32 mmol/kg with an average value of 3.72 mmol/kg and it increased with soil depth.
- The soluble sodium ions extended from 1.92 to 7.80 mmol/kg with a mean value of 4.86 mmol/kg and it increased with soil depth. The soluble potassium concentrations ranged from 0.11 to 0.34 mmol/kg with an average value of 0.23 mmol/kg and it showed an irregular trend with soil depth. The soluble cations could be ranked in the decreasing order of Na+ > Mg+2 > Ca+2 > K+.
1.2. El-Qusia soil
- Soil pH increased with soil depth for all phosphorus fertilization treatments. It changed from mildly alkaline to alkaline soil pH due to those treatments. The soil pH values were 7.83 and 8.02 at the surface and subsurface layer, respectively when the soil was treated by MCP. The corresponding values were 7.84 and 8.06 when the soil was amended by MAP. The soil pH values changed from 7.83 to 8.15 for all phosphorus fertilization treatments.
- The soil salinity (ECe) varied from 2.93 to 5.34 dS/ m with an average value of 4.14 dS/ m and it increased with soil depth. The EC values increased as a result of applying phosphorus fertilizer types and levels and it was more pronounced in the subsurface layer than that in the surface one. The maximum increase in the soil salinity of the surface layer was noticed by adding MAP since it increased by 25%. The maximum increase in the soil salinity of the subsurface layer was recorded using 125% MCP since it increased by 32%.
- The bicarbonate ions ranged from 1.63 to 3.05 mmol/kg with an average value of 2.34 mmol/kg and it decreased with soil depth. The highest value was obtained in the surface layer with 125% of MCP application while the lowest one was recorded for the control treatment. Chloride ion concentrations extended from 1.94 to 7.47 mmol/kg with an average value of 4.71 mmol/kg and they display a variable trend with soil depth. The soluble sulfate differed from 25.55 to 45.93 mmol/kg with an average value of 35.74 mmol/kg and it increased with soil depth. Generally, soluble anions in the saturated soil–paste extract of this investigated soil could be arranged in the descending order of SO42- > Cl- > HCO3-.
- The soluble calcium ions ranged from 13.26 to 20.93 mmol/kg with an average value of 17.10 mmol/kg and it increased with soil depth. Soluble magnesium varied from 3.36 to 16.14 mmol/kg with an average value of 9.75 mmol/kg and it decreased with soil depth. The soluble sodium extended from 3.34 to 25.40 mmol/kg with a mean value of 14.37 mmol/kg and it increased with soil depth. Soluble potassium ion concentrations ranged from 0.37 to 1.0 mmol/kg with an average value of 0.69 mmol/kg and it showed an irregular trend with soil depth. The soluble cations of this soil could be ranked in the decreasing order of Ca2+ > Mg+2 > Na+ > K+.
2. In Fluence of Phosphate Fertilizer Type and Level on The Soil Available (Olsen-P) Phosphorus.
2.1. Arab El-Awamer soil:
- The extractable NaHCO3-P of this soil ranged from 19.2 to 55.97 mg/kg with an average value of 31.12 mg/kg. It was noticed that the P of the surface layer was higher than that of the subsurface one at different levels of MCP application. The opposite trend was observed with MAP treatments. The highest level of P (55.97 mg/kg) was found in the surface layer amended with 125% MCP treatment. The lowest level of P (19.2 mg/kg) occurred in the surface layer of the control treatment.
2.2. El-Qusia soil:
- The NaHCO3- extractable P of this soil ranged from 12.62 to 20.89 mg/kg with an average value of 15.22 mg/kg. It was noticed that the P of the surface layer was lower than that of the subsurface one at the different levels and types of phosphate fertilizer application. The highest available level of P (20.89 mg/kg) was found in the subsurface layer treated with 75% MCP fertilizer. The lowest available level of P (12.62 mg/kg) occurred in the subsurface layer of the 100% MCP treatment.
3. Phosphorus fractionation
3.1. Arab El-awamer soil
- The recommended dose of MCP attained P concentrations of values 24.55, 44.23, 31.90, 289.75, and 96.81 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The application of 125% MCP achieved P levels of 24.92, 53.46, 41.33, 306.41, and 100.59 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The application of 75% MCP gave P values of 17.55, 42.20, 29.74, 207.90, and 96.36 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The phosphorus fractions for applying MCP treatments could be arranged in the descending order of HCl-P > Residual-P > NaHCO3-P > NaOH-P > NH4Cl-P. The recommended dose of MAP showed P levels of 19.46, 43.64, 29.65, 231.50, and 98.54 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The application of 125% MAP achieved P values of 21.40, 48.99, 40.46, 269.29, and 99.49 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The application of 75% MAP realized values of 16.57, 41.66, 29.51, 225.84, and 92.75 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The phosphorus fractions resulting from using MAP treatment, at any rate, could be arranged in the descending order of HCl-P > Res-P > NaHCO3-P > NaOH-P > NH4Cl-P.
- The relative increases in NH4Cl-P fraction were 59.1, 61.5, and 13.7% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 26.1, 38.7, and 7.4% for 100, 125, and 75% MAP treatment, respectively, compared to the control treatment. The relative increases in NaHCO3-P fraction were 17.1, 41.5, and 11.7% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 15.5, 29.7, and 10.3% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment. The relative changes in NaOH-P fraction were 14.4, 48.2, and 6.6% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 63.1, 45.1, and 5.80% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment.
-The relative increases in HCl-P form were 58.8, 68.0, and 14.0% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 26.9, 47.6, and 23.8% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment. The relative increases in Res-P fraction were 4.6, 8.7, and 4.1% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. The 6.5, 7.5, and 0.2% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment. The relative increases in Total-P fraction were 36.8, 47.9, and 10.6% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 187.0, 34.7, and 14.1% for, 125 and 75% MAP treatments, respectively, compared to the control treatment.
3.2. El-Qusia soil
- The recommended dose of MCP attained P concentrations of 3.37, 37.28, 28.39, 255.84, and 95.80 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The application of 125% MCP achieved P levels of 3.86, 39.28, 36.73, 284.46, and 126.44 mg//kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The application of 75% MCP gave P values of 2.51, 32.56, 25.67, 253.26, and 80.41 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The phosphorus fractions for applying MCP treatment could be arranged in the descending order of HCl-P > Res-P > NaHCO3-P > NaOH-P > NH4Cl-P.
- The recommended dose of MAP showed P levels of 3.17, 34.84, 26.69, 256.69, and 93.45 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-, respectively. The application of 125% MAP realized P values of 3.68, 38.00, 29.65, 281.93, and 105.62 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The application of 75% MAP achieved P values of 1.82, 31,77, 24.71, 248.33, and 76.04 mg/kg for NH4Cl-P, NaHCO3-P, NaOH-P, HCl-P, and Res-P, respectively. The phosphorus fractions resulting from using MAP treatments, at any rate, could be arranged in the descending order of HCl-P > Res-P > NaHCO3-P > NaOH-P > NH4Cl-P.
- The relative increases in NH4Cl-P fraction were 87.2, 114.4, and 39.4% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 76.1, 104.4, and 1.1% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment. The relative increases in NaHCO3-P fraction were 22.7, 29.3, and 7.1% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 14.6, 25.0, and 4.4% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment. The relative increases in NaOH-P form were 24.9, 61.6, and 12.9% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 17.4, 30.4, and 8.7% for 100, 125, and 75% MAP treatment, respectively, compared to the control treatment. The relative increases in HCl-P fraction were 15.5, 28.4, and 14.3% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 15.9, 27.3, and 12.1% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment. The relative increases in Res-P fraction were 26.9, 67.5, and 6.5% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 23.8, 39.9, and 0.7% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment. The relative increases in Total-P fraction were 19.51, 39.43, and 12.05% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. They were 17.86, 30.37 and 8.72% for 100, 125, and 75% MAP treatment, respectively, compared to the control treatment.
4. Effect Of Phosphate Fertilizer Type and Level on Biomass and Nutrient Contents of Barley Plants.
4.1. Arab El-awamer soil
- The fresh weight of barley plants increased with applying phosphate fertilizers phosphorus application nevertheless its type or level. The barley fresh weight varied between 125.69 and 178.54 g/pot. The highest value of barley fresh weight was recorded for 125% MAP while the lowest one was attained with the control treatment. The relative increases in barley fresh weight were 38.8, 37.2 and 21.4% for 100, 125, and 75% MCP treatments, respectively, the relative increases in barley fresh weight were 29.6, 42.1 and 23.3% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment.
- The dry weight of barley plants increased with phosphorus application nevertheless its type or level. The barley dry weight varied between 29.75 and 57.48 g/pot. The highest value of barley dry weight was recorded at 125% MAP while the lowest one was attained at the control treatment. The relative increases in barley dry weight were 51.2, 41.3, and 45.4% for 100, 125, and 75% MCP treatments, respectively, compared to the control one. The relative increases in barley dry weight were 52.5, 93.2, and 47.7% for 100, 125, and 75% MAP treatments, respectively, compared to the control one.
- Barley plant nutrient contents increased with phosphorus application nevertheless its type or level. The nitrogen content of barley plants varied between 2.73 and 13.04 g/kg with an average value of 7.89 g/kg. The highest value of nitrogen content of barley plants was recorded for 125% MAP treatment while the lowest one was attained with the control treatment. The relative increases in nitrogen content of barley plants were 300, 233, and 289% for 100, 125, and 75% MCP treatments, respectively, compared to the control one. The relative increases in nitrogen content of barley plants were 378, 200, and 222% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment.
- Phosphorus content of barley plants varied between 5.29 and 9.04 g/kg with an average value of 7.17 g/kg. The highest value of phosphorus content of barley plants was recorded for 100% MAP treatment while the lowest one was attained with the control treatment. The relative increases in phosphorus content of barley plants were 35.1, 27.4, and 17.4% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. The relative increases in phosphorus content of barley plants were 70.9, 22.7, and 50.3% for 100, 125, and 75% MAP treatments, respectively, compared to the control one.
- Potassium content of barley plants varied between 28.50 and 49.75 g/kg with an average value of 39.13 g/kg. The highest value of potassium content of barley plants was recorded for MAP treatment while the lowest one was attained with the control treatment. The relative increases in potassium content of barley plants were 74.5, 52.6, and 36.0% for 100, 125, and 75% MCP treatments, respectively, compared to the control one. The relative increases in potassium content of barley plants were 67.5, 48.3, and 51.8% for 100, 125, and 75% MAP treatments, respectively, compared to the control one.
4.2. El-Qusia soil
- The fresh weight of barley plants increased with phosphorus fertilizer application nevertheless its type or level. The barley fresh weight varied between 85.62 and 152.98 g/pot with an average value of 119.3 g/pot. The highest value of barley fresh weight was recorded for the MCP treatment while the lowest one was obtained with the control treatment. The relative increases in barley fresh weight were 79, 71, and 49% for 100, 125, and 75% MCP treatments, respectively, compared to the control one. The relative increases in barley fresh weight were 30, 65, and 7% for 100, 125, and 75% MAP treatments, respectively compared to the control one.
- The dry weight of barley plants increased with applying phosphate fertilizer application nevertheless of its type or level. The barley dry weight varied between 18.74 and 35.53 g/pot with an average value of 27.14 g. The highest value of barley dry weight was recorded for the MCP treatment while the lowest one was attained with the control treatment. The relative increases in barley dry weight were 78.7, 70.4, and 49.5% for 100, 125, and 75% MCP treatments, respectively, compared to the control one. The relative increases in barley dry weight were 29.6, 64.9, and 7.0% for 100, 125, and 75% MAP treatments, respectively, compared to the control one.
- Barley plant nutrient contents increased with phosphorus application nevertheless its type or level. The nitrogen content of barley plants varied between 6.83 and 17.29 g/kg with an average value of 12.06 g/kg. The highest value of nitrogen content of barley plants was recorded for 75% MAP treatment while the lowest one was attained with the control treatment. The relative increases in nitrogen content of barley plants were 32.2% for both 100% MCP and 75% MCP treatments compared to the control treatment. Moreover, increasing the MCP level by 25% showed a higher relative increase in N content of 100% MCP compared to the control treatment. The relative increases in nitrogen content of barley plants were 55.5, 37.6, and 153.2% for 100, 125, and 75% MAP treatments, respectively, compared to the control treatment.
- Phosphorus content of barley plants varied between 1.90 and 4.23 g/kg with an average value of 3.07 g/kg. The highest value of phosphorus content of barley plants was recorded for 125% MAP treatment while the lowest one was attained with the control treatment. The relative increases in phosphorus content of barley plants were 10.0, 6.3, and 97.9% for 100, 125, and 75% MCP treatments, respectively, compared to the control treatment. The relative increases in phosphorus content of barley plants were 95.8, 122.6, and 73.2% for 100, 125, and 75% MAP treatments, respectively, compared to the control one.
- Potassium content of barley plants varied between 41.25 and 57.0 g/kg with an average value of 49.13 g/kg. The highest value of potassium content of barley plants was recorded for 75% MCP treatment while the lowest one was attained with the control treatment. The relative increases in potassium content of barley plants were 0.0, 13.9, and 38.2% for 100, 125, and 75% MCP treatments, respectively, compared to the control one. The relative increases in potassium content of barley plants were 26.7, 25.6, and 34.6% for 100, 125, and 75% MAP treatments, respectively, compared to the control one.
Conclusions and Recommendations
It might be concluded that phosphorus fractions in the soil are mainly affected by some chemical properties of the soil such as soil salinity and soil reaction (pH), and different agricultural management practices, especially phosphorus fertilization. It was observed that the P of mono-ammonium phosphate was released in the soil solution faster than that of mono-calcium phosphate. Therefore, the chemical form of phosphorus fertilizer should be considered during fertilization management for maintaining adequate amounts of soil available phosphorus. Cation species (Na+, K+, and Ca2+) played a vital role in the fate of phosphorus in the soil under saline conditions they will contribute to more efficient management of phosphorus in relation to other ions. According to soil phosphorus fractionation, NaHCO3-P fraction is considered labile phosphorus, NaOH-P fraction is moderately labile phosphorus and HCl-P fraction is moderately stable phosphorus. Soil inorganic phosphorus was dominated by Ca-P fractions in calcareous soils. Also, increasing soil salinity might increase the availability of soil phosphorus. Phosphorus concentration in soil solution did not directly relate to the soil phosphorus pools, suggesting that other factors such as the hydrology or soil calcium are more important in controlling phosphorus transfer than the soil phosphorus status. As one of the recommendations of this thesis when planting barley is preferable to use mono-ammonium phosphate fertilizer in non-saline soil, while it is preferable to use mono-calcium phosphate fertilizer in saline soil. Therefore, controlling the levels of phosphate fertilizer application is essential for sustainable crop production as well as to reduce the environmental impact.