Effects of changing farm management and farm structure on energy balance and energy-use efficiency—A case study of organic and conventional farming systems in southern Germany
Hung-Chun Lin, Julia A. Huber, Georg Gerl, Kurt-Jürgen Hülsbergen
Lehrstuhl für Ökologischen Landbau und Pflanzenbausysteme, Technische Universität München, Liesel-Beckmann-Straße 2, 85354 Freising, Germany.
Fossil energy input, energy output, and energy use- efficiency (EUE) are important indicators of the environmental effects, resource consumption and economic performance of farming systems. In this study, the energy balance (process analysis) and EUE of different organic and conventional farming systems – mixed farming, arable farming, and agroforestry (AGFS) systems – were analyzed due to their importance in Germany. The analysis was based on long-term experiments at the Scheyern Research Farm in southern Germany.
The results showed that the conversion from multi-structured organic mixed farming to a specialized organic arable farming system reduced the fossil energy input in crop production only marginally (from 5.9 to 5.5 GJ ha-1 yr-1), but considerably decreased dry matter yield (from 5.4 to 2.5 Mg ha-1 yr-1), energy output (from 99 to 46 GJ ha-1 yr-1) and EUE (from 16.8 to 8.3). Improved management in the conventional arable farming system (with high-yielding varieties and better N management) reduced the energy input from 14.0 to 12.2 GJ ha-1 yr-1, increased the energy output from 155 to 179 GJ ha-1 yr-1, and elevated the EUE from 11.1 to 14.6. The establishment of AGFS with short rotation trees (without fertilization and pesticide use) led to the reduction of energy input.
Based on the results, we concluded that mixed farming is one of the best ways of producing food with high EUE under the conditions of organic farming. Therefore the conversion from organic mixed farming to an organic arable farming system is not recommended. Our AGFS results were from the first stage of a long-term experiment; it showed no negative effects on DM yield and energy output and positive effects on energy-use efficiency at this stage. However, further research is needed to know the long-term influence of AGFS.
Keywords: Energy balance; Energy-use efficiency; Mixed farming; Arable farming; Agroforestry.