The use of synthetic soil conditioners such as polyvinyl alcohol (PVA), bitumen (Bit.)  and polyacrylamide (PAC) can be considered as a specific management to improve the efficiency of the use of nitrogen fertilizers and some chemical properties of calcareous soils that are reflected in crop productivity. Two rates of synthetic soil conditioners (PAV, Bit. and PAC) and three rates of nitrogen fertilizer (50, 75 and 100% N of recommended dose) were included in this study to evaluate their effects on some chemical properties, nutritional status and yield components of both maize and wheat crops along with nitrogen use efficiency. Field experiments were conducted in calcareous soil at Nubaria Agriculture Research Station farm during two successive seasons, summer season cultivated  with maize (Zea mays L., cv Giza 10) and winter season cultivated with wheat ( Triticum aestivum L., cv Giza 168). Results showed that the highest significant yield components of maize and wheat crops along with their total content of the indicated macronutrients were observed when  applied  high rate of polyvinyl alcohol  (0.2 %) accompanied with high rate of nitrogen fertilizer  (100% N of recommended dose)  as compared to other tested treatments. On the contrary, application of high rate polyacrylamide combined with low rate of nitrogen fertilizer generally was inferior for yield components of both maize and wheat plants. Also, data revealed that the nitrogen use efficiency was the highest (65.0 and 42.4) for maize and wheat plant, respectively, receiving 50 % nitrogen fertilizer rate in presence of 0.2 % polyvinyl alcohol. However, applied high rate of polyvinyl alcohol accompanied with low rate of nitrogen fertilizer was superior decreased pH values of soil as compared to either control or other tested treatments. An opposite trend for EC values which were superior increased in presences of all nitrogen fertilizer rates. Also, CaCO₃ values were lower when applied high rate of polyacrylamide in two seasons. The highest values of available nitrate and ammonium in soil were due to applied 0.2 % of polyvinyl alcohol combined with 75 % of nitrogen fertilizer rate compared to the other tested treatments.