Abstract
Lab experiments were conducted at ascientific unit research in college of Agric. Colleg, Baghdad Univ. Soil was treated with mixture of following salts KCl ,MgCl2 , NaCl, CaCl2 to create four levels of salanity: 0.3 ,2.5 , 4.8 , 7.2 ds m-1, the treated soil samples were put in plastic cans (200gm), nitrogen fertilizer with two levels were added (as urea)(100kg N ha-1)(200N kg ha-1).The samples were incubated four weeks at 30*c. Soil samples were taken to determine NH4+ , NO3– , SAR and the number of nitrobacter and nitrosomanas bacteria. The results of the experiments showed asignificant increase in the amount of NH4+ in both treatment of tap water , the first level of nitrogen fertilizer after two weeks of incubation was 305.5 mg N kg-1 . while the amount of NH4+ decreased to 291.8 mg N kg-1 when the consentration of salinity in creased . Also there was adecline in the amount of NH4+ when the value of SAR increased and gave 281.5 mg N kg-1 soil , the elevation of salinity of the water caused reduction in the oxidation of NH4+ to NO3– which give 94.7mg N. the high salinity of water played an important role in SAR value which increased from 18 to 33.5 at 7.2 ds.m-1 , the results showed also was a clear decline in the the sailinty of water increased after four weeks of incubation number of nitrosomonas from 0.401 x 106cfu to 0.014×104 cfu . gm-1 when. we can canclude that nitrobacter bacteria more sensitive to salinity than the nitrosomonas.
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Abdul Hameed, B.A., Agric. College, Baghdad Univ.
Majaid, N. H., Agric. College, Baghdad Univ.
Farage, H. A., Agric. College, Baghdad Univ.
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