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The agricultural production of maize (Zea mays L.) increases the risk of water erosion. Perennial crops like cup plant (Silphium perfoliatum L.) offer a sustainable alternative to produce biomass for biogas plants. The assessment of soil conservation measures requires calibrated soil erosion models that spatially identify soil erosion processes. These support decision-making by farmers and policymakers. Input parameters for the physically based soil erosion model EROSION 3D for cup plant cultivation were established in a field study. Rainfall simulation experiments were conducted to determine the model input parameter's skinfactor and surface roughness. The results showed a reduction of soil erosion and higher infiltration rates for cup plant resulting in higher skinfactors of 11.5 in June and 0.75 post-harvest (cup plant) compared to 1.2 in June and 0.21 post-harvest (maize). With the extended parameter catalogue of EROSION 3D for cup plant cultivation model simulations were conducted for a rainfall event in June (64 mm). The sediment budget would have been reduced by 92.6% through the growth of cup plant in comparison to conventionally grown maize. Perennial cup plant can, therefore, contribute to achieving the targets outlined in the European Green Deal by reducing soil erosion and enhancing soil health. [ABSTRACT FROM AUTHOR]

Sustainability of biogas production is strongly dependent on soil‐borne greenhouse gas (GHG) emissions during feedstock cultivation. Maize (Zea mays) is the most common feedstock for biogas production in Europe. Since it is an annual crop requiring high fertilizer input, maize cropping can cause high GHG emissions on sites that, due to their hydrology, have high N2O emission potential. On such sites, cultivation of cup plant (Silphium perfoliatum) as a perennial crop could be a more environmentally friendly alternative offering versatile ecosystem services. To evaluate the possible benefits of perennial cup plant cropping on GHG emissions and nitrogen losses, an incubation study was conducted with intact soil cores from a maize field and a cup plant field. The 15N gas flux method was used to quantify N source‐specific N2 and N2O fluxes. Cumulated N2O emissions and N2+N2O emissions did not differ significantly between maize and cup plant soils, but tended to be higher in maize soil. Soils from both systems exhibited relatively high and similar N2O/(N2+N2O) ratios (N2Oi). N2O emissions originating from sources other than the 15N‐labelled NO3 pool were low, but were the only fluxes exhibiting a significant difference between the maize and cup plant soils. Missing differences in fluxes derived from the 15N pool indicate that under the experimental conditions with high moisture and NO3‐ level, and without plants, the cropping system had little effect on N fluxes related to denitrification. Lower soil pH and higher bulk density in the cup plant soil are likely to have reduced the mitigation potential of perennial biomass cropping. [ABSTRACT FROM AUTHOR]

Perennial energy crop (PEC) fields need to be reintegrated into the farm's crop rotation when yield performance declines after years of use or when the farm operation requires it. In this study, 8‐year‐old stands of cup plant (Silphium perfoliatum L.) and lucerne grass followed by field grass were converted to arable cropping, while continuous silage maize (Zea mays L.) grown over the same period served as a control. The study aimed to assess changes in the weed flora, control of cup plant regrowth, pre‐crop value of PECs for subsequently grown maize and N release through mineralization of crop litter and soil organic matter in the first year after converting the PECs. The previously practiced cropping systems resulted in widely divergent maize weed populations. About 90% of the cup plant volunteers were successfully eliminated by two treatments of herbicides containing clopyralid. Maize following cup plant exhibited a faster soil cover, earlier male and female flowering, taller plants and a 10.6% and 13.6% higher aboveground biomass yield than former field grass and maize respectively. The N release by mineralization of 222 and 238 kg N ha−1 following cup plant and field grass conversion, respectively, clearly exceeded the 129 kg N ha−1 observed in the maize control. The residual mineral nitrogen in the 90 cm soil profile after the maize harvest was also significantly higher in the former field grass and cup plant plots than in the maize control. The excess N in the first year after reverting to annual cropping runs the risk of N leaching. Given that N fertilization is substantially reduced after cup plant and field grass conversion, maize appears to be a well‐suited follow‐up crop due to its good suppression of cup plant volunteers and high N uptake capacity which helps minimize nutrient losses to the environment. [ABSTRACT FROM AUTHOR]

Agricultural production of biogas maize (Zea mays L.) causes hazards to aquatic ecosystems through high levels of nitrogen (N) inputs. Newly introduced and already established perennial crops such as the cup plant (Silphium perfoliatum L.) and perennial grass mixtures offer the possibility of more environmentally friendly agricultural bioenergy production. The objectives of this field study were to quantify and compare soil mineral N, water infiltration, water runoff, soil erosion and N leaching under maize, permanent cup plant, and a perennial grass mixture. The study was conducted from October 2016 to March 2019 in Braunschweig, Germany. Plots with cup plant and grass mixture exhibited lower mineral N contents than maize, especially between 30 and 90 cm soil depth. Soil water infiltration was significantly different between the three crops. The grass mixture had the highest infiltration rates (6.2 mm/min averaged across 3 years), followed by cup plant (3.6 mm/min) and maize (0.9 mm/min). During wet periods, higher N leaching was found for maize (up to 42 kg N ha−1 year−1) than for cup plant (up to 5 kg N ha−1 year−1) or the grass mixture (up to 11 kg N ha−1 year−1). While runoff and erosion for cup plant and the grass mixture were negligible during the study period, considerable amounts of runoff water and eroded sediment of up to 1.5 Mg ha−1 year−1 were collected from the maize plots despite the near flat terrain of the experimental field. Overall, permanent cup plant proved suitable as a component for energy cropping systems to reduce the risk of N leaching and soil erosion, which is particularly important for the preventive flood protection in view of the more frequent occurrence of high intensity rainfall under climate change conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Perennial energy crops as an alternative to maize (Zea mays L.) have the potential to promote biodiversity and associated ecosystem services in agricultural landscapes. Ground beetle (Carabidae) assemblages of cup plant (Silphium perfoliatum L.), Virginia mallow (Sida hermaphrodita L.) and tall wheatgrass (Thinopyrum ponticum Podp.) were assessed in four replicated field trials in Bavaria and compared to an annual crop rotation (winter rye (Secale cereale L.)), maize, winter wheat (Triticum aestivum L.)). Additionally ground beetle fauna in cup plant was compared to that in maize on fields under real farm conditions at six sites in Bavaria with widely diverging soil–climate conditions. Ground beetles were collected in pitfall traps in winter (one field trial), spring (four field trials) and summer (six fields) in 2017. Overall, results for activity density and species richness of ground beetles under perennials compared to annuals were site-specific and there were no pronounced differences of species compositions. The highest activity density of seed-eating ground beetles occurred in Virginia mallow, which was invaded by weeds. Some indication of benefits for hibernation and larval development in cup plant were found. Tall wheat-grass had the lowest ground beetle diversity and activity density of all crops. Species accumulation curves on farmed fields in summer indicated higher species richness of ground beetle fauna in cup plant than in maize. Diversification of cultivated plants with perennial energy crops can provide additional niches for ground beetles, such as undisturbed soil. Effects, however, varied with site and species/genus in a complex manner. • Assessment of ground beetle assemblages in field trials and under real farm conditions. • High importance of weeds for ground beetle diversity in novel energy crops. • Minor indications of niche enrichment by cup plant. [ABSTRACT FROM AUTHOR]

Silphium perfoliatum is a perennial crop native to North America that has been the subject of increased scientific interest in recent years, especially in Europe. It is drought- and frost-resistant, which makes it suitable for cultivation in Europe on marginal lands that are not used for growing other crops. This review analyzed the distribution and purposes of the cultivation of Silphium perfoliatum worldwide, as well as its biomass yields and characteristics as a feedstock for biogas production and other purposes. A total of 121 scientific publications on Silphium perfoliatum were identified, with the highest number (20 papers) published in 2019. It was found that higher biomass yields can be obtained at higher precipitation levels, with the use of fertilizers and an adequate type of plantation. The mean dry matter yield of Silphium perfoliatum was 13.3 Mg ha−1 DM (dry matter), and it ranged from 2 to over 32 Mg ha−1 DM. In some countries, Silphium is used as a forage crop mainly due to its high crude protein content (from 4.9% to 15% DM), depending on the vegetation phase. Silphium perfoliatum is a promising perennial crop in terms of energy and other benefits for biodiversity, soil quality and applications in medicine and pharmacology. [ABSTRACT FROM AUTHOR]