An experiment was conducted for two consecutive seasons (2004/2005 and 2005/2006) at one of the fields of Agricultural and Food Science Collage of King Faisal University to investigate the effect of Effect of soil compaction on the growth and productivity of barley and availabilityof nitrogen in soil and plant. A soil of sandy loam texture was chosen to prepare soils of different bulk density of 1.4 and 1.7 kg/cm3 to present two levels of compactions. For this purpose a plastic pipes of 60cm length and 15cm diameter were used to prepare the soil blokes. Three levels of solid Nitrogen of 0, 125, 250 kg/ha were chosen. Measurements included plant length, number of spikes, weights of roots, stems and grains. Concentration of nitrogen in soil and plant also was determined. Results showed that soil compaction (regardless of nitrogen rate) had no significant effect on weights of roots, stems. However there was a significant effect on plant length, number of spikes and grain weight in both seasons. Number of spikes decreased 7 and 14% when soil bulk density increased from 1.4 to 1.7 kg/cm3 in the first and second seasons, respectively. Grain yield also reduced 20 and 22% in the first and second seasons, respectively as the soil density increased. Significant influence on all vegetative growth and grains was observed when increasing nitrogen rates (regardless of soil density). It was found that the average stem weight of the two seasons increased 20 and 50% at 125 and 250 kg/ha nitrogen rates, respectively, also the average grain weight increased 29 and 38% at the same rates. Regardless of nitrogen rate used, concentration of nitrogen in soil, roots and stems was bigger in the soil of higher density with an increase of 21%, 7% and 16%, respectively as an average for the two seasons compared with the soil of lower density. Results showed also that in both seasons concentration of nitrogen in soil, roots and stems increased as nitrogen rate increased. It was found that concentration of nitrogen in soil increased 40% and 59% at 125 and 250 kg/ha nitrogen rates, respectively. Tillage system and suitable tractor weight at land preparation has to be highly considered achieve optimum compaction and within a condition similar to this study, it is possibly to suggest a nitrogen rate of 125 kg/ha ( 270 Urea/ ha) at soil bulk density not exceed 1.4 kg/cm3 to get the best barley yield production.