الفهرس 
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Abstract
The experimental work of present study represented in two laboratory experiments, which carried out during 2010/2011 in Mansoura University Dakahlia governorate. These experiments aim to study the nutrients availability in soil as affected by magnesium. For that, different combination of mineral fertilizers used, water content and addition of magnesium sulphate in an incubation processes with different rates of chicken manure separately. Then other experiment was used to study the effect of organic manure and magnesium on availability of nutrients during planting for 20 days in a pot experiment. The soil under study collected from the surface layer (0-20cm) at Agricultural Experimental Station Fac. of. Agric, Mansoura Univ. Soil sample air-dried and divided into two portions; the first one used in the incubation experiment using soil column and the other was stored for using it in the pot cultivation experiment.
The used treatments were as follow:
1. Incubation Experiment
Treatments were as follow: Two treatments of magnesium fertilizers:
• Without magnesium (Mg0).
• With magnesium (Mg1).
Water content at two levels:
• 100% of field capacity (W1).
• 150% of field capacity (W2).
Five treatments of mineral fertilizers:
• Control (without mineral fertilizers) (F1).
• Nitrogen (F2).
• Nitrogen + Potassium (F3).
• Nitrogen + Phosphorus (F4).
• Nitrogen + Potassium + Phosphorus (F5).
Three treatments of organic manure in a separately experiment:
• Without organic manure (OM0).
• Recommended dose of organic manure (OM1).
• Double recommended dose of organic manure (OM2).
The experimental design was spilt-spilt plot design, with three replicates where the main plots designed for magnesium fertilizer, the sub-plot for water content and the sub-sub-plot mineral fertilizers. This design was used with 2 doses of organic manure (chicken manure).
2. Pot Cultivation Experiment
Two treatments of magnesium fertilizers as following:
• Without magnesium (Mg0).
• With magnesium (Mg1).
Three treatments of organic manure as following:
• Without organic manure (OM0).
• Recommended dose of organic manure (OM1).
• Double recommended dose of organic manure (OM2).
The experimental design was spilt plot design, with three replicates where the main plots designed for magnesium fertilizer, the sub-plot for organic manure (chicken manure). The combination between organic manure and magnesium fertilizers treatments resulted in six treatments (interactions) for each cultivar of Radish crop.
The obtained results could summarize as follows:
1. Effect of treatments (magnesium, water content, mineral fertilizers and organic manure) on nutrients availability.
1.1. The single effect of the experimental treatments in the upper and lower soil sections
• The content of all av. nutrients increased significantly with adding of Mg and with 150% of field capacity in the upper and lower soil sections.
• The content of av. potassium, calcium and magnesium increased with nitrogen and potassium fertilizers addition in the upper soil section without organic manure addition.
• The content of av. phosphorus and sodium increased with adding of nitrogen, phosphorus and potassium fertilizers in the upper soil section without organic manure addition.
• The content of av. nitrogen increased with adding of nitrogen fertilizers in the upper soil section without organic manure addition.
• The content of av. potassium and calcium increased with nitrogen and potassium fertilizers addition in the lower soil section without organic manure addition.
• The content of av. phosphorus and sodium increased with nitrogen, Phosphorus and potassium fertilizers addition in the lower soil section without organic manure addition.
• The content of av. magnesium and nitrogen increased with adding of nitrogen fertilizers in the lower soil section without organic manure addition.
• The content of av. potassium increased with adding of nitrogen and potassium fertilizers in the upper soil section with recommended dose of organic manure addition.
• The content of av. phosphorus, sodium and magnesium increased with adding of nitrogen, phosphorus and potassium fertilizers in the upper soil section with recommended dose of organic manure addition.
• The content of av. nitrogen and calcium increased with adding of nitrogen fertilizers in the upper soil section with recommended dose of organic manure addition.
• The content of av. potassium, sodium and magnesium increased with adding of nitrogen and potassium fertilizers in the lower soil section with recommended dose of organic manure addition.
• The content of av. phosphorus increased with adding of nitrogen, Phosphorus and potassium fertilizers in the lower soil section with recommended dose of organic manure addition.
• The content of av. calcium and nitrogen increased with adding of nitrogen fertilizers in the lower soil section with recommended dose of organic manure addition.
• The content of av. calcium increased with adding of nitrogen and phosphorus fertilizers in the upper soil section with the double recommended dose of organic manure addition.
• The content of av. potassium, phosphorus and sodium increased with adding of nitrogen, phosphorus and potassium fertilizers in the upper soil section with the double recommended dose of organic manure addition.
• The content of av. nitrogen and magnesium increased with adding of nitrogen fertilizers in the upper soil section with the double recommended dose of organic manure addition.
• The content of av. potassium, sodium and magnesium increased with adding of nitrogen and potassium fertilizers in the lower soil section with the double recommended dose of organic manure addition.
• The content of av. phosphorus increased with adding of nitrogen, phosphorus and potassium fertilizers in the lower soil section with the double recommended dose of organic manure addition.
• The content of av. calcium and nitrogen increased with adding of nitrogen fertilizers in the lower soil section with the double recommended dose of organic manure addition.
1.2. The interaction effect of experimental treatments in the upper and lower soil sections
• The highest increasing percentage of all av. nutrients owing to Mg1W2 compared to control (Mg0W1) in the upper and lower soil sections without organic manure addition.
• The highest increasing percentage of av. potassium, phosphorus, and nitrogen and calcium owing to Mg1W2 in the upper soil section with recommended dose of organic manure addition.
• The highest increasing percentage of sodium concentration owing to Mg0W1 in the upper and lower soil sections with recommended dose of organic manure addition.
• The highest increasing percentage of av. magnesium owing to Mg1W1 in the upper and lower soil sections with recommended dose of organic manure addition.
• The highest increasing percentage of av. potassium, phosphorus, and nitrogen owing to Mg1W2 as compared to control (Mg0W1) in the lower soil section with recommended dose of organic manure addition.
• The highest increasing percentage of av. calcium owing to Mg0W2 in the lower soil section with recommended dose of organic manure addition.
• The highest increasing percentage of av. calcium, magnesium, phosphorus, and nitrogen owing to Mg1W2 as compared to control (Mg0W1) in the upper soil section with the double recommended dose of organic manure addition.
• The highest increasing percentage of sodium owing to Mg0W1 in the upper and lower soil sections with the double recommended dose of organic manure addition.
• The highest increasing percentage of av. potassium owing to Mg0W2 in the upper soil section with the double recommended dose of organic manure addition.
• The highest increasing percentage of av. calcium and magnesium owing to Mg1W1 as compared to control (Mg0W1) in the lower soil section with the double recommended dose of organic manure addition.
• The highest increasing percentage of av. potassium, phosphorus, and nitrogen owing to Mg1W2 in the lower soil section with the double recommended dose of organic manure addition.
2. Plant experiment with magnesium addition and organic manure treatments
2.1. The availability of nutrients in the soil with Mg and organic manure additions:
• The increasing percentages of nutrients availability was as follow Na > N > Mg > P > Ca > K with adding of Mg.
• The content of all av. nutrients increased significantly with OM2 treatment.
2.2. The interaction effect of experiment treatments in the soil.
• Data reveal that the highest increasing percentage of sodium owing to Mg1OM2.
2. 3. Nutrient uptake with Mg and organic manure additions:
• Increased the content of all nutrients was as follow Na> Mg> Ca > N > P > K with adding of Mg.
• The content of all av. nutrients increased significantly with OM2 treatment
2.4. The interaction effect of experiment treatments on uptake of nutrients in plant.
• Increasing uptake of magnesium, sodium, nitrogen, calcium, potassium and phosphorus with Mg1OM2.
It can be concluded that the highest mean values of the content of all Av. nutrients obtained from Mg1W2 among all treatment.
Applications of chemical fertilizers especially (magnesium, potassium and ammonium nitrate fertilizers) in the studied soils can increase availability of some nutrients in soils.
Increase the soil water content increased the availability of some nutrients.
Based on the results, it must be use fertilizers with the recommended additions and use organic manure to increase the uptake of nutrients.
In addition to this, it should be working several studies on the relationship of magnesium with each element separately and applied to the plants in the field.