Saeed Firouzi - Department of Agronomy, College of Agriculture, Rasht Branch, Islamic Azad University, Rasht, Iran
Amin Nikkhah - Young Researchers and Elite Club, Rasht Branch, Islamic Azad University, Rasht, Iran
Mehdi Khojastehpour - Department of Biosystems Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Nicholas M. Holden - UCD School of Biosystems Engineering, Agriculture and Food Science Centre, University College Dublin, Belfield, Dublin, ۴, Ireland

The energy efficiency, greenhouse gas (GHG) emissions, and carbon efficiency of paddy rice production were analysed in Sari in the Mazandaran province of Iran during 2011–2012. Data was collected through questionnaires and interviews with paddy producers. The results showed that the net energy gain was 27,932 MJ ha-1 and energy efficiency was 1.83 during production. The results of the Cobb-Douglas (CD) model showed that the energy inputs of machinery, diesel fuel, chemical fertilizers, and biocides had positive impacts on yield, while the impacts of seed and human labour were negative. For every 1 MJ increase in energy input, the inputs of seed, labour, machinery, diesel fuel, chemical fertilizers and biocides, changed the yield as -0.058, -0.992, 0.078, 0.004, 0.027, and 0.089 kg, respectively. The energy input of machinery with a high beta coefficient (0.64) had the most impact on crop yield (p≤0.01). The total GHG emission for paddy production was determined to be 1,936 kgCO2eq ha-1, with diesel fuel and machinery having the greatest contributions. Carbon efficiency was estimated to be 4.01.

Diesel Fuel, Environmental Management, sensitivity analysis, Cobb-Douglas Model