The storage of organic matter in the soil depends on the mechanisms that protect it from microbial biodegradation, by physical protection through incorporation into soil aggregates and by chemical protection through association with the mineral part of the soil (clay). Due to the lack of clay in the sandy soil, this soil contains little organic matter and its ability to exchange cations is low. The rough texture of sandy soils leads to rapid water infiltration, as water loss through percolation also carries away fine soil particles and essential nutrients. Consequently, it’s crucial to supplement soil with suitable organic and mineral amendments. In fact, nitrogen is one of the most leachable elements in sandy soils. For this reason, the potato plant grown on this type of soil requires large amounts of nitrogen at all stages of its growth. The objectives of this study are (1) to improve the physico-chemical characteristics of sandy soils in arid regions through the use of organic amendments and (2) to determine the ideal dose of mineral nitrogen fertilizer to obtain the best potato yield. In the present experiment we applied 27 t. ha−1 of cattle manure before planting. The treatments consisted of different doses of nitrogen fertilizer (N0, N0.5, N1 and N1.5) corresponding to the different doses of urea 46%: 0; 0.5; 1; and 1.5 of the potato nitrogen requirements. The highest potato yield was obtained with the nitrogen dose of 0.5 of the potato requirements, with an average of 263 qx. ha−1, but the target yield was not achieved (35–55 t. ha−1). The results of the soil analysis at the end of the experiment show that this soil contains very low levels of total nitrogen (0 and 0.56 mg. kg−1 soil) and assimilable potassium (2.98 and 3.40 meq K2O5. kg−1 soil), and medium to high levels of assimilable phosphorus (0.52 and 1.45 meq P2O5. kg−1 soil).