Experiments were conducted to manufacture and evaluate an automatic mango tree fertilizing unit suitable for Egyptian conditions. The performance of the developed machine was studied according to the following criteria: Four different machine forward speeds (1.6, 2.0, 2.5 and 3.4 km/h), three different soil moisture contents (24.51, 29.67 and 36.88%) and three different fertilizing depths (8, 12 and 20cm). The performance of the manufactured machine was evaluated taking into account the following indicators: the amount of fertilizer needed for each tree, field capacity, field efficiency, specific energy requirement and operating costs. The fertilizer is applied when the unit's arm touches the tree and falls next to the tree at the specified fertilization depth. The optimum operating parameters for the developed mechanized tree fertilizing unit were found at machine forward speed of 2.0 km/h, fertilizing depth of 8 cm, soil moisture content of 36.88%, which gave a field capacity of 1.9 fed/h, fertilizing efficiency of 79.17%, field efficiency of 78.84 %, quantity of fertilizer 791.7 g/tree, specific energy consumption 2.61 kWh/fed and operating costs of this manufactured machine 153.3 LE/fed.