Timothy E. Crews

Perennial cropping systems offer promise to address many of the issues associated with high-input, industrial agriculture. Kernza, a domesticated variety of intermediate wheatgrass (Thinopyrum intermedium), and perennial wheat, a hybrid between Kernza and annual durum wheat (Triticum turgidum subsp. durum), are two perennial cereals developed for such a system. Recently domesticated crops such as Kernza may still possess beneficial belowground traits that have been lost in modern cereals through extensive aboveground-focused plant breeding. If so, such traits may also have been passed down to perennial wheat. We conducted a greenhouse experiment to characterize relationships between root architecture, exudate profiles, and microbial communities in Kernza and perennial wheat in relation to annual wheat. We collected exudate samples from 8-week-old plants and analyzed them via LC-MS/MS for their chemical composition. We extracted DNA from rhizosphere soils and sequenced them for 16S and ITS amplicon profiles. Lastly, we scanned the roots to analyze root distribution across diameter classes. We found that perennial wheat invested more heavily into very fine (< 250 µm) roots and exuded at a greater rate per amount of root biomass compared to Kernza. We suspect that the greater proportion of very fine roots in perennial wheat led to greater surface area and greater specific exudation rate. While we did not find evidence of a genotype effect on root exudate or microbial community composition, we did find a significant association between root architecture and root exudates, and between root exudates and the rhizosphere community. These interactions represent a potential pathway through which plants influence their rhizosphere microbial community. Understanding rhizosphere dynamics and the response to domestication and hybridization can guide further development of robust perennial cereal crops.

Managing Kernza [ Thinopyrum intermedium (Host) Barkworth & Dewey] as a dual‐use crop for grain and forage has potential to improve economic viability, particularly in organic systems where premiums and diversified outputs can enhance profitability. We evaluated how the timing and frequency of Kernza forage harvest affected grain and forage yields, forage composition, and weed pressure in organic systems. A 4‐year study (2020–2023) was conducted across five diverse environments in the US Midwest. Four forage harvest strategies coupled with an annual grain harvest were evaluated: (1) a single summer harvest (1x‐Su), (2) spring and summer harvests (2x‐SpSu), (3) fall and summer harvests (2x‐FaSu), and (4) fall, spring, and summer harvests (3x‐FaSpSu). Forage harvest timing and intensity affected forage nutritive value more than grain or total forage yields. Strategies including spring harvests (2x‐SpSu and 3x‐FaSpSu) improved overall nutritive value by increasing total crude protein from 5%–6% to 10% and increasing total relative feed value from 70–80 to 80–92 compared to summer harvest alone (1x‐Su). Grain yields were impacted by stand age, declining substantially over time, ranging from 385–860 kg ha ⁻¹ in Year 1 to 45–224 kg ha ⁻¹ in Year 4 across sites, while forage yields remained relatively stable (2.8–4.8 Mg ha ⁻¹ in Year 1 to 2.2–7.5 Mg ha ⁻¹ in Year 4). Weed biomass was similar among treatments but increased in Year 4, which can be a consideration for termination timing of Kernza. Our findings show that well‐timed forage harvests may improve forage quality without sacrificing productivity, offering organic farmers more flexible and profitable management for this perennial grain crop.

Perennial cropping systems offer promise to address many of the issues associated with high-input, industrial agriculture. Kernza, a domesticated variety of intermediate wheatgrass (Thinopyrum intermedium), and perennial wheat, a hybrid between Kernza and annual durum wheat (Triticum turgidum subsp. durum), are two perennial cereals developed for such a system. Recently domesticated crops such as Kernza may still possess beneficial belowground traits that have been lost in modern cereals through extensive aboveground-focused plant breeding. If so, such traits may also have been passed down to perennial wheat. We conducted a greenhouse experiment to characterize relationships between root architecture, exudate profiles, and microbial communities in Kernza and perennial wheat in relation to annual wheat. We collected exudate samples from 8-week-old plants and analyzed them via LC-MS/MS for their chemical composition. We extracted DNA from rhizosphere soils and sequenced them for 16S and ITS amplicon profiles. Lastly, we scanned the roots to analyze root distribution across diameter classes. We found that perennial wheat invested more heavily into very fine (< 250 µm) roots and exuded at a greater rate per amount of root biomass compared to Kernza and annual wheat. We suspect that the greater proportion of very fine roots in perennial wheat led to greater surface area and greater specific exudation rate, and that this may be related to hybrid vigor. While we did not find evidence of a genotype effect on root exudate or microbial community composition, we did find a significant association between root architecture and root exudates, and between root exudates and the rhizosphere community. These interactions represent a potential pathway through which plants influence their rhizosphere microbial community. Understanding rhizosphere dynamics and the response to domestication and hybridization can guide further development of robust perennial cereal crops.

Societal Impact Statement: Annual cereal grains account for ~50% of human food calories, but cultivation of these crops has resulted in major environmental and social issues worldwide. For nearly three decades, researchers have been breeding intermediate wheatgrass—a perennial cool‐season grass—to serve as the world's first commercial‐scale perennial grain crop to improve agricultural sustainability. Introducing a perennial grain crop onto landscapes and into markets has significant potential to reduce environmental impacts of agriculture, improve farmer economics, and offer a healthy new food ingredient for consumers. However, transdisciplinary collaboration is required to upscale Kernza to maximize positive societal impacts. Summary: Kernza is the tradename of grain harvested from advanced breeding lines of intermediate wheatgrass, a perennial grass being domesticated to serve as a perennial grain crop. Here, we present the need and justification for developing perennial grains as a contributing solution to agricultural challenges; we review the foundational science behind Kernza's development, outline the transdisciplinary efforts to scale and commercialize it, and address the unique challenges to its wider adoption and integration into the food system. Decades of plant breeding and development of genetic resources have resulted in the domestication of Kernza, which has since been studied for its food science, agronomic, and ecological properties at a research scale. Research and development have expanded to engage critical food system actors including farmers, processors, end‐users, and consumers, and these collaborations have resulted in coordinated networks ranging in scale from local communities to an international consortium to improve the social, environmental, and economic impacts of Kernza. Cross‐sector partnerships continue to develop and distribute knowledge and resources that support the adoption of Kernza by growers and end users. Examples of resources include grower business cooperatives, federal incentive programs, marketing toolkits, and educational materials for learners spanning generations. We outline key challenges to expedited progress, including the inherent time requirements to breed a crop for multi‐year grain production, and quantify certain environmental benefits like carbon sequestration. A coordinated, transdisciplinary, values‐based approach to overcoming these challenges is described and, if implemented, can accelerate the research and commercialization at a global scale.

Societal Impact Statement: Soils are globally degraded due in part to conventional agriculture and wildland conversion. To address the global challenge of soil degradation, we formed an interdisciplinary, cross‐institutional collaborative research team, New Roots for Restoration, to understand how perennial plant root and shoot traits relate to one another, and how they influence and are influenced by plant communities and the soil. We highlight how coordinated research projects, expertise cores, and cross‐institution training activities simultaneously advance scientific understanding and workforce development. We share approaches and tools, as well as challenges and lessons learned. This institute highlights how multi‐institution teams integrating diverse biological subdisciplines can advance major scientific and training goals. Summary: The challenge of restoring degraded soils must be met with integrated knowledge and practice of distinct biological subdisciplines. Here we share a model of scientific collaboration, an interdisciplinary cross‐institution team: New Roots for Restoration Biology Integration Institute (NRR). NRR focuses on how plant organismal systems (roots and shoots) relate to one another, and how those relationships influence and are influenced by plant communities and the soil ecosphere. Our aim is to enhance the ability to predict belowground functional traits from aboveground phenotypes to identify ecologically and functionally appropriate materials to restore natural ecosystems and to develop sustainable agricultural systems of the future. Plants provide the ecological and structural foundation of terrestrial landscapes, building soils and supporting productivity in natural and agricultural ecosystems. Plants connect aboveground components through their root systems in terrestrial ecosystems to the soil ecosphere. However, the field lacks a basic understanding of how plant traits, from roots to shoots, govern these connections. This is especially true for perennial plants, which are inherently difficult to study. NRR seeks to elucidate how attributes of the plant organismal system (plant traits, genetics, genetics × environment interactions), community ecology, and the soil ecosphere contribute to variation in aboveground and belowground plant structures through 10 integrated projects supported by expertise cores. Our efforts demonstrate how the integration of biological subdisciplines can advance understanding of the impacts of deep‐rooted plant systems in both restored grasslands and perennial agroecosystems.

Phosphorus (P) is a finite resource essential for food production currently lost from fields at an unsustainable rate via runoff and crop harvests. These losses could be addressed by pairing peren­nial crops, which reduce runoff with their deep roots that stabilize the soil, with recovering nutri­ents from human excreta. Urine contains the majority of P and other nutrients that humans excrete and therefore has been the focus of recent nutrient reclamation efforts. Urine fertilizer has yet to be explored for perennials, however, and under­standing the biophysical effects of urine ferti­lizer on soil nutrients and biomass in perennial crops could inform the design of a more circular food system. To that end, we started the first known workplace urine nutrient reclamation pro­ject in the state of Kansas, U.S., to test the feasibil­ity of supplying available soil P from urine to alfalfa (Medicago sativa), a perennial legume forage crop. After one growing season, urine fertilizer had no effect on aboveground biomass but did increase available soil P which otherwise decreased in the control treatments. Urine also increased soil nitrate and sodium compared to the water-only controls. The field study was coupled with a survey of staff members who participated in urine collection to identify opportunities and potential barriers to urine diversion in the U.S. The survey revealed a lack of awareness of both unsustainable P manage­ment and urine recovery as a potential solution, underscoring the need for increased education. Regulatory challenges faced in the second field sea­son also highlighted the need for policy that explic­itly defines urine separately from wastewater in the U.S. We hope that results from this project will make it more feasible to conduct additional studies and circular food system community-based pro­jects on a larger scale going forward.

Societal Impact Statement: Agricultural practices have had a negative impact on the physical, chemical, and biological components of soil. Perennial cropping systems that facilitate positive soil microbial interactions could not only rebuild soils but also sustain productivity through expected variations in environmental conditions. Here, we show the presence of arbuscular mycorrhizal (AM) fungi, soil symbionts that can improve host performance and soil health, increased the growth of intermediate wheatgrass, a novel perennial grain crop, in populations that have been increasingly bred for desirable agricultural characteristics. The right pairing of intermediate wheatgrass and a beneficial AM fungal community could lead to more sustainable agroecosystems.Summary: Intermediate wheatgrass (IWG) is a novel perennial grain that can provide many soil health benefits in agroecosystems; however, little is known about how selection for agronomic traits has impacted interactions with soil biota. Here, we assess how the selection for agronomic traits in IWG has impacted its relationship with arbuscular mycorrhizal (AM) fungi. First, growth response to AM fungi was compared across five generations of IWG with varying degrees of selection. Second, variation in AM fungal responsiveness was compared among genets of IWG individuals within a more advanced generation. Finally, a meta‐analysis was performed on all published studies exploring AM fungal inocula effects on IWG performance to increase understanding of selection effects. AM fungal responsiveness increased with selection for agronomic traits, responsiveness varied among genets in the advanced generation, and a majority of genets performed better in the presence of AM fungi. The meta‐analysis supported the findings that AM fungal responsiveness has increased with selection in IWG. Further studies are needed to realize the combined potential soil health and sustainability benefits of IWG and AM fungi, including assessment of symbiotic benefits beyond biomass production, identification of IWG traits correlated with responsiveness, and characterization of AM fungal community response to IWG.

First paragraphs: A great deal of attention is currently focused on how agriculture in highly industrialized coun­tries contributes to greenhouse gas (GHG) emis­sions, and how certain farming innovations might curb the emissions of nitrous oxide and methane and draw down carbon dioxide from the atmos­phere. What is not being discussed is how agricul­ture in general, and grain agriculture in particular, will need to change as society phases out its dependency on fossil fuels in order to achieve carbon (C) neutrality. Over the last century in the U.S., the number of farmers on the land declined by about 66%, in close proportion to the increase in average farm size (U.S. Department of Agriculture Economic Research Service [USDA ERS], n.d.). Integral to these trends has been the simplification of farming systems in which practices like fertility-generating rotations have been replaced with lower-diversity monocultures maintained by applications of fossil fuel–based fertilizers and pesticides (Crews & Peoples, 2004). Between fossil fuel–powered mechanization and fossil fuel–based input intensi­fication, the energy used by farmers to grow maize in the state of Nebraska is 99.7% from fossil fuels and 0.3% human labor (Grassini & Cassman, 2012; Pimentel & Pimentel, 2008). Even organic farming systems often require prodigious fossil fuel inputs with intensive tractor tillage, manure hauling, and mechanical harvesting (Smith et al., 2015). In con­trast to our modern grain-producing agroeecosys­tems, ancestral agroecosystems and natural ecosys­tems of all types—forests, grasslands, deserts, tundra—have remained productive for millennia with no fossil fuel inputs. In this commentary I explore the dependency of grain agriculture on fossil fuel use in the U.S. set in a global context, and approaches for reducing this dependency, including a shift to perennial polycultures that rely on ecological intensification in place of energy-intensive inputs. . . .

Aim. Generalization of literary sources and familiarization of the scientific community and agro-producers about the perennial culture of various purposes, as well as the need to conduct research on the technological aspects of growing wheatgrass medium or intermediate under the Kernza® trademark in Ukraine. Methods. General scientific analysis and synthesis, analogy and generalization of scientific literary sources and practice. Results. The rich, deep Chernozem soils of Ukraine were formed under the influence of diverse, perennial grassland vegetation. The conversion of grassland ecosystems to annual grains initiated a process of soil degradation that continues to this day. This is because the termination of vegetation required to sow annual crops results in unsustainable levels of soil erosion, loss of soil organic matter, leaching of nutrients, reduced rain infiltration, and a less functional soil microbiome. In recent decades, researchers in the USA and increasingly around the world have begun to develop perennial grain crops that have the potential to reverse the soil degradation associated with annual grain crops. One of the most promising perennials being developed is a dual purpose grain and forage crop derived from intermediate wheatgrass - IWG (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey). The grain from IWG is known under the trade name Kernza®. New research in Ukraine is needed to assess the potential economic and environmental benefits of cultivating Kernza across diverse soil and climatic zones. This paper outlines the environmental and food-related roles of Kernza, including its history of development and dissemination in the USA and worldwide, its contribution to safeguarding environmental quality and food security, specific aspects of intermediate wheatgrass cultivation technology, and the justification for its expansion in Ukraine. Ukraine’s unique combination of climate, soils, and agrarian culture position it to be a potential leader in the regenerative transition to a perennial agriculture. Conclusions. Varieties of Kernza wheatgrass (Thinopyrum intermedium (Host) Barkworth & DR Dewey) are a new promising perennial grain crop that deserves comprehensive study and distribution in the conditions of Ukraine. Kernza is a promising perennial crop that deserves to be grown in Ukraine. Additional research is needed in Ukraine to develop Kernza varieties adapted to the soils and climate of Ukraine, and to document the best agronomic practices for growing Kernza in different regions of the country.