Two Novel Energy Crops: Sida hermaphrodita (L.) Rusby and Silphium perfoliatum L.—State of Knowledge

Abstract

<jats:p>Current global temperature increases resulting from human activity threaten many ecosystems and societies, and have led to international and national policy commitments that aim to reduce greenhouse gas emissions. Bioenergy crops provide one means of reducing greenhouse gas emissions from energy production and two novel crops that could be used for this purpose are Sida hermaphrodita (L.) Rusby and Silphium perfoliatum L. This research examined the existing scientific literature available on both crops through a systematic review. The data were collated according to the agronomy, uses, and environmental benefits of each crop. Possible challenges were associated with high initial planting costs, low yields in low rainfall areas, and for Sida hermaphrodita, vulnerability to Sclerotinia sclerotiorum. However, under appropriate environmental conditions, both crops were found to provide large yields over sustained periods of time with relatively low levels of management and could be used to produce large energy surpluses, either through direct combustion or biogas production. Other potential uses included fodder, fibre, and pharmaceutical uses. Environmental benefits included the potential for phytoremediation, and improvements to soil health, biodiversity, and pollination. The review also demonstrated that environmental benefits, such as pollination, soil health, and water quality benefits could be obtained from the use of Sida hermaphrodita and Silphium perfoliatum relative to existing bioenergy crops such as maize, whilst at the same time reducing the greenhouse gas emissions associated with energy production. Future research should examine the long-term implications of using Sida hermaphrodita and Silphium perfoliatum as well as improve knowledge on how to integrate them successfully within existing farming systems and supply chains.</jats:p>

Bioenergy Crops: Current Status and Future Prospects

“…Under suboptimal conditions of water and phosphorous shortage a higher yield stability of the crop mixtures was demonstrated, which makes them a suitable agronomic alternative to sole cropped maize or sorghum. Similar positive results for intercropping the perennial energy crop S. hermaphrodita with perennial legume species was also demonstrated in earlier studies, and was highlighted in the review-article on this crop by Cumplido-Marin et al [3].…”

“…Both studies clearly identified beneficial effects of the biogenic residues on plant performance in the given experimental time in maize. Such positive effects of digestate application in sand and other soils were also described in earlier greenhouse and outdoor studies using the perennial plant S. hermaphrodita as a promising bioenergy carrier, as described and summarized in the review-article by Cumplido-Marin et al [3]. Overall, in terms of declining mineral phosphorus resources and to reduce the high energy demand for nitrogen and mineral fertilizers in general, nutrient recycling becomes an important issue particularly for bio-energy crop production.…”

“…Alternative perennial second generation energy crops such as Virginia mallow (Sida hermaphrodita L. Rusby), cup plant (Silphium perfoliatum L.), and giant miscanthus (Miscanthus x giganteus) that do not directly compete with food or feed have received considerable research attention in recent years and continue to be investigated, as is also shown in this special issue [3][4][5]. Among the use of such crops solely as energy carriers, higher value, and in return energy savings, could be achieved by emphasizing more the use of its biomasses for material applications.…”

Ecological Intensification of Food Production by Integrating Forages

“…In recent years, the majority of research on cup plant has focused on its potential as a substitute for maize in biogas production in Europe, especially Germany [197][198][199]. While maize is somewhat higher yielding than cup plant, diversification of bioenergy feedstocks in agricultural landscapes is generally desirable and cup plant is perceived as providing more ecosystem services than maize [198].…”

Gasification of Cup Plant (Silphium perfoliatum L.) Biomass–Energy Recovery and Environmental Impacts

“…As a result of the conducted study, it was determined that cup plant dry weight yield increased with the increase in the level of fertilization and irrigation ( Figure 2). Other cultivation studies have shown that irrigation increases yields by 50%, while fertilization does so by more than 25% [33]. The greatest yield, i.e., 15.12 Mg ha −1 , was obtained for object W(+)/N80, and the difference between objects W(−)/N80 and W(+)/N80 was only 7.6%, testifying to the minor impact of irrigation on the dry weight yield at this fertilization dose.…”