Investigations on the energy efficiency of organic and integrated farming with specific emphasis on pesticide use intensity

One organic farming treatment (OF) and two integrated farming treatments (IF) with (i) situation-related pesticide use (100% HF), and (ii) application rates reduced by 50% in relation to (i), (50% HF), were compared with regard to energy efficiency. Data were used from a long-term field experiment (1997-2006) conducted on a sandy soil with moderate soil fertility and continental climate in the Federal State of Brandenburg, Germany. Net energy output, energy intensity (i.e. energy input per unit grain equivalent (GE), which makes possible comparisons between different crops related to their contributions to human or animal nutrition), and output/input ratio were used as indicators to determine the energy efficiency. Owing to different rates of mineral nitrogen (N) fertilizers in the two IF treatments from 1997 to 2001, all calculations were split for the periods 1997-2001 and 2002-2006, respectively. Energy efficiency tended to be lower in winter wheat compared with winter rye in OF and IF because of higher yields obtained while less energy was required for rye cropping. Averaged across all years and crops, the fossil energy inputs in OF (8.1GJha⁻¹) were 35% lower than in the IF treatment 100% HF (12.4GJha⁻¹). The largest shares of energy input in IF were diesel fuel (29%) and mineral fertilizers (37%). Mineral nitrogen (N) fertilizers represented 28% of the total energy input in IF. Pesticide use was attributable for 5% of the total energy input in 100% HF. In OF, most energy was needed for diesel fuel (46%). Significantly higher net energy outputs were recorded for 100% HF compared with OF in winter rye and winter wheat as well as in the entire crop rotation. However, no significant differences in net energy output were found between 100% HF and 50% HF. The energy intensity was significantly lower and the output/input ratio higher in OF compared with IF in the period from 1997 to 2001, whilst no significant differences between both farming systems concerning the two indicators were recorded from 2002 to 2006.