Industrial crop cultivation on marginal agricultural land limits indirect land-use change effects that pose a threat to food security. This review compiles results from 91 published crop-specific field trial datasets spanning 12 relevant industrial crops and discusses their suitability for cultivation on unfavorable soil types (USTs). It was shown that the perennial species Miscanthus (Miscanthus Andersson) and reed canary grass (Phalaris arundinacea L.) performed well on USTs with both high clay and/or high sand contents. Information on stoniness (particles sizes > 2 mm), where mentioned, was limited. It was found to have only a small impact on biological yield potential, though it was not possible to assess the impact on mechanization as would be used at a commercial scale. For soils with extreme clay or sand contents, half of the crops showed moderate suitability. The large yield variations within and between crops revealed large knowledge gaps in the combined effects of crop type and agronomy on USTs. Therefore, more field trials are needed on diverse USTs in different climates with better equipment and more consistent measurements to improve the accuracy of potential yield predictions spatially and temporally. Additionally, larger trials are needed to optimize cultivation and harvesting.

Lignocellulosic biomass from marginal land is needed for a social–ecologically sustainable bioeconomy transition. However, how much biomass can be expected? This study addresses this question by reviewing the limitations of current biomass yield modeling for lignocellulosic crops on marginal land and deriving recommendations to overcome these limitations. It was found that on the input side of biomass yield models, geographically limited research and the lack of universally understood definitions impose challenges on data collection. The unrecognized complexity of marginal land, the use of generic crop growth models together with data from small-scale field trials and limited resolution further reduce the comparability of modeling results. On the output side of yield models, the resistance of modeled yields to future variations is highly limited by the missing incorporation of the risk of land use changes and climatic change. Moreover, several limitations come with the translation of modeled yields into bioenergy yields: the non-specification of conversion factors, a lack of conversion capacities, feedstock yield–quality tradeoffs, as well as slow progress in breeding and the difficulty of sustainability criteria integration into models. Intensified political support and enhancement of research on a broad range of issues might increase the consistency of future yield modeling.

Agricultural land in Europe is affected by low rooting depth (LRD) on 27.9 Mha. This marginal agricultural land can potentially be used to grow industrial crops without directly threatening food security or biodiversity conservation. However, little is known about the yield performance of industrial crops at LRD conditions. This study therefore compiles and discusses the meaningful data available in scientific literature. Twelve relevant industrial crops were identified for Europe. Currently, robust information on good growth suitability for LRD conditions is available for only one industrial crop, namely reed canary grass (RCG). Because this information was taken from field trial results from a single site, it remains unclear what role other growing conditions such as soil quality and climate play on both the yield level and the biomass quality of RCG under LRD conditions. These uncertainties about the quantitative as well as qualitative performance of industrial crop cultivation on marginal agricultural land characterized by LRD represent a major agronomic knowledge gap. Here, more knowledge needs to be compiled through both expanded crop science activities and improved international information exchange to make more optimal use of the large LRD areas available for the transition to a bioeconomy.

About 8.37 Mha of European agricultural land is affected by low temperature and thus considered marginal agricultural land. This land allows for industrial crop cultivation without competing directly with food security or biodiversity conservation. However, little is known regarding the yield performance of industrial crops under low temperature conditions. This study therefore compiles the available data and discusses them in the context of remaining uncertainties. Overall, 12 industrial crops were identified as relevant for Europe: giant reed (Arundo donax L.), camelina (Camelina sativa L. Crantz), cardoon (Cynara cardunculus L.), crambe (Crambe abyssinica Hochst ex R.E.Fr.), cup plant (Silphium perfoliatum L.), hemp (Cannabis sativa L.), miscanthus (Miscanthus spp.), poplar (Populus L.), reed canary grass (Phalaris arundinacea L.), sorghum (Sorghum bicolor L. Moench), switchgrass (Panicum virgatum L.), and willow (Salix L.). Good or very good growth suitability under low temperature was indicated for camelina, upland switchgrass, reed canary grass, and willow. Nevertheless, it was also found that there are strong variations in yield performance within the selected industrial crops. Little information was found on the effects of marginality constraints on biomass quality. The uncertainty resulting from this fragmentary data situation represents one of the greatest challenges to the large-scale implementation of industrial crop cultivation across European agricultural land prone to low temperatures, especially in the context of climate change.