Research of efficiency of conventional production of mercantile corn was held on production parcels in agroecological conditions of Posavina in a period of vegetation in 2017. In order to define costs of crop management from the point of view of energy and production aspects, in certain stages of production of corn grain, energy consumption and utilization of the horsepower of the tractor was monitored. During working operations the maximum amount of fuel was spent for ploughing ( plough Leopard- L 30.3 VK aggregated with tractor Belarus 82.1 ) 26,4 l/ha, while the smallest amount was spent in chemical crop protection ( sprayer RAU aggregated with tractor Universal UTB 450 ) 2,7L/ha. Accordingly, efficiency in various operations of production varied within 10-20% span. In our experiment efficiency varied from 6,91% during fertilization to 23,33% in the process of ploughing, which is in this case within optimum limits. In direct input almost one third or 27,13% went for the basic tillage system ( 81,77 kWh/ha ) with a very high fuel usage of 23,33%. If we look at energy value of production of corn grains energy output will be 75243,20 MJ/ha with a ratio of 16,178 which is considered to be quite high, and productivity of 1,273 kg/MJ. In order to get the full picture of the above production of corn and energy outcome and not concentrating only on grain production, it is essential to include in energy analysis significant amounts of plant residues, that is maize biomass, which doubles the mentioned energy ratio to 31,846 and hence overall productivity of energy circulation in this production.