Ongoing human industrial activities have led to elevated atmospheric greenhouse gas concentrations that are negatively impacting global climate, natural ecosystems, and human health [1]. Preventing these emissions through halting fossil fuel combustion is implausible in the short term, so alternate energy solutions such as biofuels are being researched. A major concern with biofuels is the food vs fuel controversy, in which food security is compromised due to food or feed crops being replaced by bioenergy feedstocks. However, 11% of the continental USA (~ 86.5 million ha− 1) is considered marginal land [2]. Marginal land is defined as land on which growing conventional food crops is not economically profitable due to biophysical hazards or environmental externalities that require increased management practices to maintain productivity [3–5]. Many promising bioenergy feedstocks have developmental and physiological characteristics that enable them to remain productive and economically viable in these marginal lands unsuitable for conventional crops, thus circumventing the food vs fuel controversy [6, 7].
A type of bioenergy feedstock capable of growing on marginal land is warm season perennial grasses. These species require low inputs and maintenance costs and have high adaptability to marginal lands relative to annual crops [8, 9]. Additionally, these species actively provide ecosystem benefits, such as preventing soil erosion and performing water filtration via their extensive root systems. They also support biodiversity by providing habitat to insect and bird species [10].
A common trait of marginal landscapes is waterlogging due to poor drainage, and/or flooding in poor soils [4]. Waterlogged soil in early spring can delay planting, and cause yield losses due to diseases associated with wet, cool soil conditions [11, 12]. In addition, flooding reduces the soil oxygen available to plants which reduces root respiration, creating unfavorable conditions for plant growth [13]. Late season waterlogging can also cause difficulties in field operations due to standing water in fields [12].
Multiple warm season perennial grass species should be developed to accommodate the various growing conditions across US, primarily species showing high biomass production on marginal lands [14]. Prairie cordgrass (Spartina pectinata Link) is a tall, rhizomatous perennial grass indigenous to many regions throughout US and Canada [15, 16]. It is native to marshes, drainage ways and moist prairies in North America [15, 16] and including land that is too wet for annual crops, such as corn and soybean [17]. Due to prairie cordgrass’s tolerance to salt, alkaline conditions, and flooded conditions, in addition to its adaptability to both dryland and wet soils, this species could potentially be grown on a variety of soil conditions [15, 18, 19].
Miscanthus × giganteus (hereafter, M. × giganteus) is a warm-season perennial grass produced by a cross between Miscanthus × sinensis and Miscanthus × sacchariflorus [20, 21]. It has a high biomass yield potential [22], reported to have yields ranging from 22 to 35 Mg ha− 1 in Illinois, USA [23]. Mature stands of high yielding M. × giganteus have even yielded about 40 Mg ha− 1 in Europe [24, 25]. It is also moderately tolerant to heat stress, cold stress, drought, salinity, and flooding [14], making it a possible feedstock for marginal lands.
Switchgrass (Panicum virgatum L.) can grow in a wide range of environments and requires little moisture or nutrient inputs to produce a reliable biomass yield [26, 27]. Specifically, “Kanlow” switchgrass shows tolerance to flooded conditions [28]. Similar to M. × giganteus, switchgrass has good drought tolerance and moderate tolerance to heat, cold, salinity and flooding, making it another candidate for a biomass feedstock grown in marginal environments [14, 28, 29].
Big bluestem (Andropogon gerardii Vitman) is notable for its high tolerance to drought, heat, and salinity [14]. Although big bluestem is primarily considered for forage purposes, it also has bioenergy potential [30, 31]. It can additionally be used for mine reclamation, Midwest prairie restoration, and erosion control [32, 33].
Developing these species for use as bioenergy crops would efficiently utilize the waterlogged soils of Illinois and related regions. However, no studies have been conducted that compare the biomass potential of these new bioenergy consideration grasses with that of prairie cordgrass, when grown in the same environment under the same culture. In addition, the effect of row spacing on these grass species needs to have further investigation. Determining plant spacing is an important step, as this management decision may influence yield and chemical composition of a stand for multiple years. Therefore, the objectives of this research were to 1) determine the biomass yield performance and tissue lignocellulosic composition of switchgrass, M. × giganteus, prairie cordgrass, and big bluestem grass species in wet marginal land and 2) determine the effect of row spacing on yield performance of the compared grass species on such land. We hypothesize that due to being native to wet prairies, prairie cordgrass may tolerate the wet marginal condition better and thus produce more biomass yields than the other three species. Our results will help us identify the best performers in the given environmental conditions in this experiment and further assist biomass crop breeding and development programs.