The paper evaluates the relation between energy input (E_i) and output (E_o) of biogas production from six energy crops: maize, sorghum, sunflower, triticale, reed canary grass (RCG), and Virginia mallow (VM), cultivated in three different nitrogen fertilization levels. Furthermore, in the case of RCG, the impact of cutting system was examined. The results showed that raised N fertilization dose (in the range of 40–120 kg ha⁻¹ and 80–160 kg ha⁻¹, depending on the crops) increased biomass yield and methane productivity (MP) but simultaneously caused also the increase in E_i. Nonetheless, the application of higher N doses did not cause drastic decrease in energy use efficiency (EUE). The E_i was significantly lower for perennials than for annual crops. For this reason, EUE for RCG harvested in two cuts (5.0–5.2 GJ GJ⁻¹) was close to EUE for maize (5.7–6.8 GJ GJ⁻¹), despite the much lower MP (2027–2903 m³ ha⁻¹ and 4409–5692 m³ ha⁻¹, respectively) and E_o (73–105 GJ ha⁻¹ and 159–205 GJ ha⁻¹, respectively). Furthermore, the collection of RCG in more than two cuts turned out to be unjustified, due to increase in E_i and, simultaneously, decrease in MP.

本文评估了六种能源作物种植的玉米，高粱，向日葵，小黑麦，芦苇金丝雀草（RCG）和弗吉尼亚锦葵（VM）的沼气生产的能量输入（E _i）和输出（E _o）之间的关系。三种不同的氮肥水平。此外，对于RCG，研究了切割系统的影响。结果表明，提高氮肥的施用量（在40-120 kg ha ^-1和80-160 kg ha ^-1之间，具体取决于作物）增加了生物量产量和甲烷生产率（MP），但同时也导致了氮肥的增加。 Ë_我。但是，施用更高剂量的N并不会导致能量使用效率（EUE）的急剧下降。电子_我多年生植物明显低于一年生作物。因此，尽管MP值低得多（2027–2903 m ³  ha ^-1），但两次收获（5.0–5.2 GJ GJ ^-1）收获的RCG的EUE接近玉米（5.7–6.8 GJ GJ ^-1）的EUE。和4409-5692米³ 公顷^-1，分别地）和E _ø（73-105 GJ公顷^-1和159-205 GJ公顷^-1分别）。此外，由于E _i的增加和MP的减少，在两个以上的切割中收集RCG的结果是不合理的。