الفهرس 
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Abstract
A pot experiment was performed under greenhouse conditions to study the efficiency of nitrogen fertilizers in contaminated soils, under the effect of some inorganic amendments (gypsum and rock phosphate) and organic amendments (compost) and their interaction at the Farm of Soil, Water and Environment Research Institute, Agricultural Research Center, Mansoura, Dakahlia Governorate, Egypt during winter season (2010-2011) using wheat plants (Triticum aestivum L.) cultivar Sakha 93.
Plastic pots having 35cm diameter and 50cm height were filled with 10 kg soil. Before filling the pots, the treatments of soil amendments were mixed thoroughly with the investigation soil before sowing. Gypsum was added at rate of 4 t fad-1 (40 g/pot), compost was added at rate of 4 t fad-1 (40 g/pot) and rock phosphate at rate of 400 kg fad-1 (4 g/pot). Lead treatments were also added before sowing at rate of 200 mg kg-1 (2000 mg Pb /pot) soil as PbSO4 (solid) and cadmium treatments were added at rate of 25 mg kg-1 soil (250 mg Cd /pot) as CdSO4 (liquid) after two weeks form sowing.
Treatments of nitrogen forms were added at rate of 100 mg N kg-1 (1000 mg N/pot) soil as ammonium nitrate (33.5%), ammonium nitrate + nitrification inhibitor (thiourea) and bentonite coated urea (37% N). The inhibitor was added at rate of 5% of added nitrogen.
Results can be summarized as follows:
There was a clear effect of soil amendments, nitrogen sources and pollutants on growth yield and mineral constituents of wheat plant at tillering and booting stages. At harvesting stage, ammonium nitrate plus nitrification inhibitor followed by bentonite coated urea (BCU) gave the highest mean values of straw and grains total nitrogen, phosphorus and potassium uptake at all treatments of pollutants. The values of nitrogen efficiency ratio (N.E.R) of wheat straw and grains at different stages of plant growth were slightly affected by different treatments. Treating the soil with compost or rock phosphate decreased the concentration of lead and cadmium in wheat straw and grains at harvesting stage. The application of ammonium nitrate combined with nitrification inhibitor followed by bentonite coated urea (BCU) tended to increase the residual available nitrogen phosphorus and potassium in soil, either with or without pollutants. Finally, the application of ammonium nitrate combined with nitrification inhibitor followed by bentonite coated urea (BCU) were the best N-source , either with or without pollutants. the effect of soil amendments illustrated that compost gave the greatest values of dry matter, total nitrogen phosphorus and potassium uptake and available nitrogen phosphorus and potassium in soil by wheat plants at different stages followed by rock phosphate and gypsum, the orders can be arranged as following: compost > rock phosphate > gypsum> control. It could be concluded that compost reduced the hazard effect of pollutants on wheat plants by controlling the mobility of lead and cadmium, in soil.