ABSTRACT

Following a cradle-to-farm-gate approach, we determined the input of fossil energy and greenhouse gas emissions (GGE) for conventional and agroforestry land use on a farm in a low profit region of Germany. On the basis of a calculation model with a recurring crop rotation of maize, rye, oat, and a catch crop mixture, it was found that a short rotation alley cropping system (SRACS) with a 10% (A10) and a 40% (A40) tree area for bioenergy production consumed 7% and 32% less fossil energy than the conventionally managed site (C). Simultaneously, the net energy gains and energy efficiency of the plant production process were increased by up to 8 and 53%, respectively. Likewise, the operational GGE accumulated to 3.1 Mg ha⁻¹ yr⁻¹ under C farming and could be reduced by 9% and 36% in A10 and A40, respectively. Overall, a multidimensional land use indicator comparison proved that under specific site conditions agroforestry land use can increase the energy output per unit of land area, while the energy input and GGE per metric ton of biomass yield were considerably lower than in C farming. Nominal range sensitivity analysis revealed that the energetic and ecological performance of the system was highly sensitive to the size and productivity of the tree area as well as to the use of fertilisers. Our findings suggest that SRACS may fundamentally improve the environmental and energetic performance of the cultivation process on marginal land, without leading to substantial losses in agricultural livestock production area.

摘要

按照从摇篮到农场的方法，我们确定了德国低利润地区农场的常规能源和农用土地使用的化石能源和温室气体排放量（GGE）。根据玉米，黑麦，燕麦和农作物混合物的轮作轮作的计算模型，发现短轮作巷道种植系统（SRACS）的比例为10％（A10）和40％（ A40）用于生物能源生产的树木面积比常规管理的土地（C）消耗了7％和32％的化石能源。同时，工厂生产过程的净能源收益和能源效率分别提高了8％和53％。同样，运行中的GGE累积到3.1 Mg ha ^-1 yr ^-1在C耕作下，A10和A40分别降低了9％和36％。总体而言，多维土地利用指标比较证明，在特定的场地条件下，农林业用地可以增加单位土地面积的能源输出，而能源输入和每公吨生物量产量的GGE则大大低于C耕作。标称范围敏感性分析表明，该系统的能量和生态性能对林区的大小和生产力以及肥料的使用高度敏感。我们的研究结果表明，SRACS可以从根本上改善边际土地上耕作过程的环境和能量性能，而不会导致农业畜牧生产区的大量损失。