Energy use and economic analysis of corn silage production under three cultivated area levels in Tehran province of Iran

This study was carried out on energy consumption patterns in different sizes of farms for corn silage production. Data were collected from 40 producers, using face to face questionnaire method in Karaj city. The survey studies indicated that the most important energy inputs were machinery and chemical fertilizers with 42% and 28% of total energy input, respectively. The total consumption energy was 68,928 MJ ha−1 where the output was 148,380 MJ ha−1. The results showed that farms with more than 10 ha use the least amount of total energy per hectare. The energy ratio, energy productivity, specific energy and net energy were 2.27, 0.28 kg MJ−1, 3.76 MJ kg−1 and 79,452 MJ ha−1 respectively. Share of direct and indirect energy was 25% and 75% respectively. The econometric model was developed using Cobb–Douglas type function. The elasticity coefficients of diesel fuel, chemical fertilizers, machinery and seed were found to be statistically significant. The MPP (Marginal Physical Productivity) value showed the high impact of seed and chemical fertilizers energy inputs on corn silage yield. The economic analysis showed average total cost of production as 1973 $ ha−1 that was higher in large farms; however more yield led to better benefit to cost ratio. The GHG emissions were indicated the high CO2 output in machinery production.