Energy use and carbon emission of conventional and organic sugar beet farming

The efficiency and environmental impact of sugar beet production can be measured using a variety of energy consumption and carbon emission indicators, respectively. The goal of the present study was to analyse the energy and carbon emission indicators of sugar beet production systems that involved different farming methods and farm sizes. More specifically, we analysed the effects of five tillage practices used in conventional farming systems (deep ploughing, shallow ploughing, chiselling, discing, and no tillage), four non-chemical weed control practices used in organic farming systems (inter-row loosening, inter-row cutting and mulching, smothering with white mustard, and thermal control), and five farm sizes (2, 10, 20, 40, and 80 ha). For conventional sugar beet production, the greatest efficiency (efficiency ratio of 9.59, specific energy of 0.41 MJ kg−1, and energy productivity of 2.41 kg MJ−1) were obtained by disc harrow soil loosening on 80-ha farms. For organic production, the lowest energy input (25862 MJ ha−1) and specific energy (0.46 MJ kg−1) and the greatest yield (55.82 t ha−1), energy efficiency ratio (8.21), and energy efficiency (22.16 kg MJ−1) were obtained using inter-row loosening on 80-ha farms. The most environmentally friendly conventional farming process, in terms of carbon emissions (carbon input of 825.7 kg ha−1, carbon emission ratio of 19.75), involved no tillage technology on 80-ha farms, whereas the most environmentally friendly organic farming process (carbon input of 4606 kg ha−1, carbon emission ratio of 4.85) involved inter-row loosening. Farm size also influenced efficiency and environmental impact; as farm size increased from very small (2 ha) to large (80 ha), the total energy input for the conventional and organic farming systems increased from 6.5 to 10.9% and from 7.9 to 9.6%, respectively, and the carbon input decreased from 9.9 to 14.9% and from 3.1 to 4.0%.