Abstract: A field experiment was carried out in the autumn season (2021) in Al-Tokiya village/ Qalaat Sukkar district/ Dhi Qar governorate, Iraq. It is located 100 km to the north of Nasiriyah city center at a height (15 m) above sea level. The aim of this study was to improve the growth performance and yield of maize by the effect of magnesium fertilization on the availability of nutrients in the experiment soil. The experiment was applied according to a randomized complete block design (RCBD) with a factorial experiment. Three replications with three varieties of maize were applied. Each of treatment was treated with four levels of magnesium sulfate (MgSO4.H2O) (T1 ground fertilization, T2 leaves and ground fertilization + T3 leaves fertilization and T0 controls). The treatments were distributed to the experimental units (12) with dimensions of (4×3) m2. Each experimental unit included (4 lanes with a length of 4 m, a distance of 70 cm between plants. Distance of (2 m2) between the experimental unit, 1m2 variety and 2 m2 between duplicate and another were applied. Three seeds were placed in each hole. After three week of planting, thinning process was carried out. The data were collected according to the analysis of variance table. The means were analyzed according to the least significant difference test (LSD) at the level of (0.05). The most important results are summarized as follows: T3 fertilization (ground + leaves fertilization) was significantly superior in PH, magnesium, sulfur, nitrogen, phosphorous, potassium in soil, magnesium, sulfur, nitrogen. Phosphorous, potassium in plants, chlorophyll content in leaves of female flowering, number of grains in the ear, grain yield per ton/h, protein percentage in grains, sulfur in grains. The results showed that 6.83, 263.6 mg kg-1 soil 12.43 mg kg-1 soil, 15.19 mg kg-1 soil, 11.85 mg kg-1 soil, 196.9 mg kg-1 soil, 0.38 cmol L-1 0.28 cmol L-1, 2.17 cmol L-1, 0.33 cmol L-1, 2.78 cmol L-1 392 mg m-2, 67.11 days, 671