Evaluation of energy balance and greenhouse gas emissions in rice cultivation in Guilan province, northern Iran

The agricultural sector as a supplier of nutritional needs is becoming increasingly dependent on energy consumption. The present study was carried out to investigate the effect of paddy farm level of mechanization on the energy balance and greenhouse gas emissions as well as their effect on rice cultivation in Guilan province, Iran. The survey contains a strategy for assessing sustainable development in the agricultural sector and protecting the environment. To this end, the indicators of energy efficiency and the amount of greenhouse gas emissions from inputs were analyzed. The data used in this study were gathered from questionnaires during the crop years of 2013–2014. Data were grouped based on the level of mechanization. According to the results of the two groups, there was a significant difference in terms of energy input consumption, and direct, renewable, and non-renewable energies, and greenhouse gas (GHG) emissions. Net energy in high and low mechanization levels of 19,340.55 and 20,237.18 MJ ha−1 was calculated for the crop season, respectively. The share of indirect energy in both groups was approximately 80%. The renewable and non-renewable energy usages based on input were 35 and 65% in high mechanization level. Similarly, for low mechanization level, these ratios were 37 and 63%. In the high mechanization level, 44% of total greenhouse gas emissions were from diesel, 31% from nitrogen, and 13.5% from machinery. Also, in the low mechanization group, 40% of the total greenhouse gas emissions were due to nitrogen fertilization, 35.5% of diesel consumption and 11% of machinery. It should be noted that in both groups, agricultural pesticides account for less than 10% of greenhouse gas emissions. Carbon efficiencies, being the ratio of yield’s carbon content to carbon emissions, were estimated to be 10.67 and 12.85 in high and low mechanization levels, respectively. Therefore, it is implied that the low mechanization level group is more eco-friendly. The results of the Cobb–Douglas model in the low mechanization level showed that the impact of the energy input of irrigation water was positive, while that of the energy inputs of diesel fuel, chemical fertilizers, labor, and pesticides was negative.