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Ecosystem benefits of winter‐killed annual cover crops are less studied than winter hardy annuals. The objectives of this study were to determine (1) the effects of tillage practices and cover crop mixtures on biomass and soil cover of cover crops seeded into nearly mature maize (Zea maysL.) and soybean [Glycine max(L.) Merr.] and (2) if cover crop biomass can be estimated from soil surface coverage measurements. The study was conducted within two long‐term tillage trials from 2016 to 2018. Tillage included conventional—(CT), strip—(ST), and no‐till—(NT). Cover crops included annual ryegrass (AR; Lolium multiflorumL.); AR and crimson clover (CC; Trifolium incarnatumL.) mixture (ARCC); AR, CC, and forage radish (FR; Raphanus sativusL.) mixture (ARCCFR); and no‐cover (NC). Seeding rates for AR, ARCC, and ARCCFR were 28, 36, and 40.5 kg ha−1, respectively. The ARCCFR mix produced the most biomass (256 kg ha−1), followed by AR (174 kg ha−1) and ARCC (165 kg ha−1). Cover crop biomass was 260 and 136 kg ha−1in maize and soybean; and 218, 201, and 177 kg ha−1in CT, ST, and NT, respectively. Cover crop soil coverage between rows was 25% in maize and 14% in soybean. Cover crop biomass was associated with soil surface coverage (R2= 0.841). Given that cover crop biomass drives ecosystem services associated with cover crops, limited biomass and ground coverage of winter killed cover crops seeded into nearly mature maize and soybean may not add ecosystem services in the upper Midwest. Conventional tillage produced the highest cover crop biomass.Biomass of late interseeded cover crop in maize and soybean was limited.High cover crop biomass was not always due to species diversity.Annual ryegrass biomass was higher than crimson clover and forage radish in mixtures.Cover crop soil coverage was strongly associated with cover crop biomass.

Soil functional zone management (SFZM) is a novel strategy for row crop management. Especially when used with cover cropping, SFZM may play an important role in enhancing agricultural production and sustainability via beneficial effects on soil nitrogen cycling. Field studies in four states across the U.S. showed that SFZM can enhance control of nitrogen cycling, increasing nitrogen availability near crop roots in synchrony with corn peak nitrogen demand. Earn 0.5 CEUs in Soil & Water Management by reading this article and taking the quiz at www.certifiedcropadviser.org/certifications/self‐study/800.

Over the last half‐century, crop breeding and agronomic advances have dramatically enhanced yields in temperate summer‐annual cropping systems. Now, diversification of these cropping systems is emerging as a strategy for sustainable intensification, potentially increasing both crop production and resource conservation. In temperate zones, diversification is largely based on the introduction of winter‐annual and perennial crops at spatial and temporal locations in annual‐crop production systems that efficiently increase production and resource conservation. Germplasm development will be critical to this strategy, but we contend that to be feasible and efficient, germplasm improvement must be closely integrated with commercialization of these crops. To accomplish this integration, we propose a novel approach to germplasm development: the reflective plant breeding paradigm (RPBP). Our approach is enabled by developments in genomics, agroecosystem management, and innovation theory and practice. These developments and new plant‐breeding technologies (e.g., low‐cost sequencing, phenotyping, and spatial modeling of agroecosystems) now enable germplasm development to proceed on a time scale that enables close coordination of breeding and commercialization (i.e, development of cost‐effective production systems and supply–value chains for end‐use markets). The RPBP approach is based on close coordination of germplasm development with enterprise development. In addition to supporting strategic diversification of current annual‐cropping systems, the RPBP may be useful in rapid adaptation of agriculture to climate change. Finally, the RPBP may offer a novel and distinctive pathway for future development of the public plant‐breeding programs of land‐grant universities with implications for graduate education for public‐ and private‐sector plant breeders.

Increasingly, funding agencies are investing in integrated and transdisciplinary research to tackle “grand challenge” priority areas, critical for sustaining agriculture and protecting the environment. Coordinating multidisciplinary research teams capable of addressing these priority areas, however, presents its own unique set of challenges, ranging from bridging across multiple disciplinary perspectives to achieve common questions and methods to facilitating engagement in holistic and integrative thinking that promotes linkages from scholarship to societal needs. We propose that structural equation modeling (SEM) can provide a powerful framework for synergizing multidisciplinary research teams around grand challenge issues. Structural equation modeling can integrate both visual and statistical expression of complex hypotheses at all stages of the research process, from planning to analysis. Three elements of the SEM framework are particularly beneficial to multidisciplinary research teams; these include (i) a common graphical language that transcends disciplinary boundaries, (ii) iterative, critical evaluation of complex hypotheses involving manifest and latent variables and direct and indirect interactions, and (iii) enhanced opportunities to discover unanticipated interactions or causal pathways as empirical data are tested statistically against the model. Using our ongoing multidisciplinary, multisite field investigation of climate change adaptation and mitigation in annual row crop agroecosystems as a case study, we demonstrate the value of the SEM framework for project design, coordination, and implementation and provide recommendations for its broader application as a means to more effectively engage and address issues of critical societal concern.

New innovation systems are needed to help agriculture meet its “grand challenges.” These systems should integrate the major streams of discovery in agricultural bioscience (biotechnologies and agroecotechnologies) and engage this and other research with private enterprise, civil society, and government sectors, to develop new agricultural systems that meet high standards for performance in economic, social, and environmental terms. To create and sustain such innovation systems, a critical mass of agricultural bioscientists is needed with certain skills, understandings, and inclinations that enable constructive and ongoing participation in innovation systems. To achieve this critical mass, graduate education will play a crucial role. We outline a graduate curriculum for this purpose, similar in scope to a graduate minor program; it features two foundational courses, experientially based short courses and student experiences in cross‐sector innovation systems. The curriculum is now being pilot‐tested at the University of Minnesota with a cohort of 11 students, but is well suited to multi‐institutional implementation. Initial evaluation data suggest that the first year of the curriculum promoted development of certain relevant skills and inclinations in an initial cohort of seven students.

Agriculture is offering new forms of support to society, as evidenced by rapid development of an agricultural “bio-economy,” and increasing emphasis on production of ecological services in farmed landscapes. The advent of these innovations will engage agricultural professionals in critical civic debates about matters that are complex and that will often be controversial, and thus demand new sets of professional capacities that extend significantly beyond technical expertise. Specifically, agriculturalists will need a capacity to facilitating challenges to, and where appropriate, changes in prevailing worldviews—their own as well as those of others. In this article we report on pedagogy that aims to build such capacity, via a semester-length course on critical engagement in sustainable development of agricultural and other managed ecosystems. In the course we aimed to help prepare students to engage as professionals in critical discourse under circumstances where prevailing worldviews about agricultural development vary significantly among different stakeholders. We used experiential learning to encourage students to critically examine individual and collective worldviews and “mental models” relevant to sustainable development challenges. Experiential learning was particularly featured in an extended exercise in “scenario planning,” a method of systemic analysis of alternative scenarios of future development in which the students began to function as a critical learning system. In reflective and evaluative essays, students indicated favorable evaluations of their learning experience and provided evidence of increased capacities highly relevant to civic professionalism within the context of the quest for sustainability as agriculture offers new forms of life support to society.

There is a need for improved soil and water conservation in the corn (Zea maysL.)–soybean [Glycine max(L.) Merr.] rotation common to the upper Midwest, and an appropriate cover crop may fulfill this need. A corn–soybean rotation that included a rye (Secale cerealeL.) cover crop was studied at two Minnesota locations in 2002 and 2003 to evaluate rye management method and timing for no‐till soybean production. Fall‐planted rye following corn harvest at Waseca and Rosemount was managed the next spring by: (i) mowing once, (ii) mowing twice, (iii) applying glyphosate herbicide once, (iv) applying herbicide twice, and (v) mowing once followed by applying herbicide, with four mow dates beginning 1 May separated by approximately 1 wk. Rye regrowth after mowing but before stem elongation in early to mid‐May was similar to that of uncut rye but decreased dramatically when mowed at anthesis in early June. At Rosemount, low weed populations and the presence of the rye cover crop, when properly managed, had only a minimal affect on soybean yield, resulting in the one‐pass mowing system being equally profitable as the no‐rye two‐pass herbicide system. At Waseca, where weed pressure was high, the rye cover crop treatments without subsequent herbicide application as well as the early one‐pass herbicide applications did not provide adequate control, making these systems less profitable. Our research indicated soybean yields following a rye cover crop were often comparable to yields where no rye cover crop was grown, but economic returns were usually reduced.

We describe our pedagogical approaches and experiences with a novel course in agroecology (one semester, three credit-hours, for graduate students and upper level undergraduates). Our course responds to recent proposals that agroecology expand its disciplinary focus to include human factors as well as ecological factors, thus taking a more holistic and systemic perspective. The course structure and service-learning component are organized around the focal concept of “transformation,” that is, a systemic change that addresses a certain ecological problem in an agricultural system. Our goal is to help train agricultural professionals who can work effectively in collaborative efforts to implement such transformations. Toward this end, we have integrated methods from systems thinking, soft-systems methodology, and agroecosystems analysis, and used a service-learning component to provide students with an opportunity to apply and evaluate these methods in practice. Most students favorably evaluated the course. Ultimately, we expect that the course will help our students to develop a civic professionalism through which they apply their professional skills to complex public problems in agriculture.

In ecology, tradeoff theory has been used to understand differences among plant species in their competitive abilities. In efforts to develop weed-suppressive soybean, we found evidence of a tradeoff between the ability for rapid initial growth and the ability for sustained growth later in the season: early maturing lines displayed more rapid initial growth but ceased growth sooner. Such a tradeoff would increase the difficulty of obtaining a full-season weed-suppressive variety. To determine this tradeoff's existence and severity we examined two possible mechanisms that could lead to it. We tested whether early maturing soybean lines attain higher early relative growth rate than late-maturing soybean lines and whether early maturing soybean lines produce larger seeds by an environmentally-dependent or -independent mechanism. Early maturing lines had higher relative stem elongation rates than late lines but not higher relative dry weight or leaf area increase rates. In more northern locations and in years with shorter growing seasons, early maturity lines produced larger seeds than late maturing lines, implicating an environmentally-dependent rather than -independent mechanism causing seed size differences. Relative to early lines, when late lines mature, temperature and photoperiod are in greater decline, leading to a risk of incomplete seed fill. Resulting seed size decreases could lead to lower initial growth in late maturity lines and thus to an environmental rather than genetic or physiological cause of tradeoff between initial growth and sustained growth later in the season.