This research was carried out at Meet Aly village, Dakahlia governorate in summer season 2013 to determine the optimum parameter which can be used to control fertilizing with variable rate technique. To achieve the aim of this research at two fertilizer prototype on row was developed by adding an electronic gate on/off (developed unit) to that hand gate on/off system (traditional unit) on the same prototype. Four forward speeds were applied namely 3.38, 4.38, 4.79 and 6.70 km/h once at fixed fertilizer rate (150 kg/fed) by traditional unit, and another at variable fertilizing rate by developed unit. To evaluate the fertilizer units performance the amount of nitrogen in soil, fuel consumption, field capacity and cost estimation were determined. From the results it can concluded that using the developed fertilizer unit; a controlled by the electronic system on/off gate saved the amount of fertilizer to 56.8 kg/fed and total costs to 209.36 LE/fed at forward speed of 4.79 km/h. It can be recommended that the applied developed technique can be tested in a large scale to test its efficiency and suggest another methodology other than soil chemical analysis such as GIS maps.