The cultivation of perennial instead of annual energy crops has received growing interest. Previous studies identified numerous beneficial effects of perennial energy crop (PEC) cultivation for the agricultural landscape such as promotion of agrobiodiversity, reduced requirements for agrochemicals and fertilizers as well as a large potential for carbon accumulation in soil. However, the mere presence of soil organic matter (SOM) accumulation gives no indication about the persistence of the SOM for example after a recultivation of the stands. Therefore, this study focused on SOM pools of different density fractions and soil microbial parameters. Six different PECs were tested against a typical benchmark system as feedstock for anaerobic digestion. The study has shown that all PEC species increased soil microbial activity and provided an insight how they sequester carbon in soil. Moreover, significant modifications in basic soil properties caused by plant growth were observed. For example, the cultivation of giant knotweed has lowered the soil pH by more than 0.5 pH units compared to the benchmark system. After 5 years of PEC cultivation, total soil organic carbon stocks were increased between 1,500 ± 400 and 4,500 ± 1,500 kg C ha^‐1 for the upper 10 centimetres of soil. The distribution among different soil fractions showed species‐specific patterns. Tall wheatgrass and Virginia mallow showed particular high accumulation rates in the mineral‐associated SOM fraction which indicates long residence times of the SOM after a possible recultivation of the fields.

中文翻译：

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多年生能源作物下土壤有机碳的分配和动态及其对土壤微生物量和活性的反馈

多年生而不是一年生能源作物的种植受到了越来越多的关注。先前的研究确定了多年生能源作物（PEC）种植对农业景观的众多有益影响，例如促进农业生物多样性，减少了对农药和化肥的需求以及土壤中碳积累的巨大潜力。但是，仅存在土壤有机质（SOM）积累就不能表明SOM的持久性，例如在林分再造之后。因此，本研究集中于不同密度分数和土壤微生物参数的SOM库。针对典型的基准系统（作为厌氧消化的原料）测试了六种不同的PEC。该研究表明，所有PEC物种均增加了土壤微生物的活性，并为他们如何螯合土壤中的碳提供了见解。此外，观察到由植物生长引起的基本土壤性质的显着改变。例如，与标准系统相比，巨型虎杖的种植使土壤pH值降低了0.5个pH单位以上。经过5年的PEC种植，土壤有机碳总量增加了1,500±400至4,500±1,500 kg C ha^‐1表示土壤的上方10厘米。不同土壤组分之间的分布表现出特定物种的模式。高大的小麦草和弗吉尼亚锦葵在与矿物相关的SOM组分中显示出特别高的积累速率，这表明在可能的田间耕作后，SOM的停留时间较长。