Optimal crop management can reduce energy use and greenhouse gases emissions in rainfed canola production

Energy use and greenhouse gases (GHG) emissions in rainfed canola production in north eastern Iran were analyzed to find measures to reduce energy use and GHG emissions. Four production scenarios, i.e. a high-input, a low-input, a better crop management and a usual scenario, evaluated. All activities and production processes were monitored and recorded over three consecutive years. The usual scenario consumed 13 GJ ha-1 energy input, resulted in 52 GJ ha-1 energy output and GHG emissions of 1028 kg CO2-eq ha-1 and 556 kg CO2-eq t-1. The key factors relating to energy use and GHG emissions were nitrogen fertilizer and fuel for field operations. Compared to the usual production scenario, the better crop management production scenario was significantly more efficient; it consumed 25% less input energy, needed 17% lower amount of nitrogen fertilizer, but resulted in 35% more grain yield and output energy. This scenario also resulted in 26% less GHG emissions per unit field area and 45% less GHG emissions per ton of grain. Measures of improvement in energy use and GHG emission were identified.