The low adoption of annual cover crops in the United States Corn Belt has motivated research into novel cover cropping systems that mitigate the degrading of water quality due to soil and nutrient loss without compromising corn (Zea mays L.) yield. This 3-year field study compared a Kentucky bluegrass (Poa pratensis L.) as a perennial groundcover (PGC), two interseeded annual cover crop systems (standard and wide-row), and a no-cover control for their effects on corn yield and subsurface drainage water quality. Each plot was monitored weekly for subsurface drainage flow and nutrient losses using a randomized complete block design with three replicates. The study occurred during a period of below-average precipitation, which caused strong year-to-year and seasonal variations in treatment performance. Treatment effects were most evident in the study's wettest year, when increased rainfall following a dry season caused a summer nitrate flush. During this high-leaching summer period, all cover crop systems reduced nitrate concentrations compared to the control. When averaged across the entire study, the high-biomass wide-row interseeded system reduced flow-weighted NO3-N concentrations by 22% but reduced grain yield 20%. In contrast, the PGC system reduced NO3-N by 20% with no associated grain yield loss. These findings highlight a critical yield trade-off for wide-row annual cover cropping systems and suggest that perennial systems like Kentucky bluegrass PGC are a promising strategy for mitigating early summer nitrate losses.

Achieving high yields in the large-scale agricultural systems that dominate the US landscape requires critical machine-enabled field operations to be executed in narrow windows of time. Novel cropping systems hold great promise to increase ecosystem services from these large-scale systems, but researchers and end-users need effective methods of representing the timing requirements of such systems. This gap prompted our exploration of approaches to visualize the timing of critical machine-enabled field operations. We refer to the resulting graphic as a field operations visualizer (FOV). We iterated multiple versions of the FOV through a user-centered process involving extensive stakeholder feedback. The resulting FOV version offers a straightforward method of visualizing operation sequences and identifying potential conflicts. Survey results suggest that the FOV provides significant operational insights to users about the timing challenges (or benefits) of novel cropping systems. The FOV may therefore be useful in guiding efforts to improve novel cropping systems and to thereby ultimately increase their deployment to deliver ecosystem services.

Perennial groundcover (PGC) has promise as a scalable approach to generating natural resource benefits and sustainable biofuel feedstock while preserving the high yields of annual row crop production. Partnering row crops with temporally and spatially complementary low-growing, shallow-rooted perennials, such as Kentucky bluegrass (KBG) (Poa pratensis L.), is one example of an emerging PGC system. PGC’s ecosystem benefits can only be fully realized if commercial-scale adoption occurs, which hinges on its economic feasibility. This paper utilizes an enterprise budget framework to detail and compare the expected cost and revenue of establishing and maintaining PGC in row crop systems with standard continuous corn (SCC) (Zea mays L.) production, including stover harvest, but excluding economic incentives for ecosystem services. Optimistic and pessimistic assumptions were used, along with Monte Carlo simulation, to characterize the uncertainty in results. In the optimistic stover market scenario, Year 1 net returns for PGC averaged USD 84/ac less than for SCC; Year 2+ net returns averaged USD 83/ac more, meaning that cost parity with SCC occurs by the second PGC system year. Without stover revenue, parity is achieved after five years. These results affirm that PGC’s economic viability is critically impacted by a groundcover’s lifespan, the yield parity with SCC, and the availability of a stover market.

Livestock in the state of Iowa, United States (US) produce over 50 × 106 Mg of wet-basis manure yearly. Biogas production from manure’s anaerobic digestion (AD) can reduce greenhouse gas emissions, control odors, and provide renewable energy. Despite these benefits, AD is rarely deployed at swine farms in Iowa. In this work, we explore the economics of AD systems in Iowa to evaluate reasons for low deployment and explore the production cost impacts of biogas cleaning and injection into the natural gas grid, amending manure with biomass, and centralizing digesters across multiple farms. This work presents a static, spreadsheet-based technoeconomic model that embodies literature-based estimates of key system technical parameters, costs, and transportation fuel incentives and permits the examination of various scenarios. Key findings include that under the model assumptions, distributed, farm-scale digesters are not competitive with average natural gas prices in Iowa. A centralized production scenario can be competitive, provided that programs such as the low-carbon fuel standard (LCFS) and the renewable fuel standard (RFS) have sufficiently high credit values.

A growing global meat demand requires a decrease in the environmental impacts of meat production. Cultured meat (CM) can potentially address multiple challenges facing animal agriculture, including those related to animal welfare and environmental impacts, but existing cost analyses suggest it is hard for CM to match the relatively low costs of conventionally produced meat. This study analyzes literature reports to contextualize CM’s protein and calorie use efficiencies, comparing CM to animal meat products’ feed conversion ratios, areal productivities, and nitrogen management. Our analyses show that CM has greater protein and energy areal productivities than conventional meat products, and that waste nitrogen from spent media is critical to CM surpassing the nitrogen use efficiency of meat produced in swine and broiler land-applied manure systems. The CM nutrient management costs, arising from wastewater treatment and land application, are estimated to be more expensive than in conventional meat production. Overall, this study demonstrates that nitrogen management will be a key aspect of sustainability in CM production, as it is in conventional meat systems.

Integrating perennial groundcovers (PGC) - sometimes referred to as living mulches or perennial cover crops - into annual cash-crop systems could address root causes of bare-soil practices that lead to negative impacts on soil and water quality. Perennial groundcovers bring otherwise absent functional traits - namely perenniality - into cash-crop systems to preserve soil and regenerate water, carbon, and nutrient cycles. However, if not optimized, they can also cause competitive interactions and yield loss. When designing PGC systems, the goal is to maximize complementarity - spatial and temporal separation of growth and resource acquisition - between PGC and cash crops through both breeding and management. Traits of interest include complementary root and shoot systems, reduced shade avoidance response in the cash-crop, and PGC summer dormancy. Successful deployment of PGC systems could increase both productivity and profitability by improving water- and nutrient-use-efficiency, improving weed and pest control, and creating additional value-added opportunities like stover harvest. Many scientific questions about the inherent interactions at the cell, plant, and ecosystem levels in PGC systems are waiting to be explored. Their answers could enable innovation and refinement of PGC system design for multiple geographies, crops, and food systems, creating a practical and scalable pathway towards resiliency, crop diversification, and sustainable intensification in agriculture.

Iowa's livestock produces over 50 million tons of wet-basis manure each year. Biogas production from the manure can provide additional income to farmers, reduce greenhouse gas emissions, control odors, and provide a renewable energy source. Despite these benefits, biogas production is rarely deployed at swine farms. In this work, we explore the system economics to understand better the reasons for low deployment, as well as the benefits that might be realized via several additional steps, including: (1) cleaning and injection into the natural gas grid, (2) amending manure with biomass, and (3) digester centralization. Specifically, we present a static, spreadsheet-based techno-economic model that allows examining these scenarios and combinations thereof. We also present our results and the uncertainties therein. This work shows that under the model assumptions, distributed, farm-scale digesters are not competitive with natural gas prices in Iowa, while some centralized production scenarios can be competitive, providing that fertilizer value and RIN credits are sufficiently high.

Technoeconomic analyses using established tools such as SuperPro Designer® require a level of detail that is typically unavailable at the early stage of process evaluation. To facilitate this, members of our group previously created a spreadsheet-based process modeling and technoeconomic platform explicitly aimed at joint fermentative‒catalytic biorefinery processes. In this work, we detail the reorganization and expansion of this model—ESTEA2 (Early State Technoeconomic Analysis, version 2), including detailed design and cost calculations for new unit operations. Furthermore, we describe ESTEA2 validation using ethanol and sorbic acid process. The results were compared with estimates from the literature, SuperPro Designer® (Version 8.5, Intelligen Inc., Scotch Plains, NJ, 2013), and other third-party process models. ESTEA2 can perform a technoeconomic analysis for a joint fermentative‒catalytic process with just 12 user-supplied inputs, which, when modeled in SuperPro Designer®, required approximately eight additional inputs such as equipment design configurations. With a reduced amount of user information, ESTEA2 provides results similar to those in the literature, and more sophisticated models (ca. 7%–11% different).

HighlightsMixing amaranth grain and maize is a promising pesticide-free method for controlling maize weevils in stored maize.A 1:1 mixture by volume of maize and amaranth reduced the number of live weevils by 66% after 160 d of storage as compared to maize stored without amaranth.A further reduction in live weevils could be achieved by completely covering all maize kernels with a layer of amaranth.Insect-infested maize-amaranth mixtures had reduced spoilage due to mold during storage as compared to insect-infested maize stored without amaranth.Abstract. Amaranth (Amaranthus spp.) is used as a vegetable, food, forage, and sometimes an ornamental. Amaranth grain has higher protein content than other cereals, making it a good choice for human consumption. Maize is among the three most widely grown grains in the world, but it can experience large postharvest losses during storage due to infestation by the maize weevil (Sitophilus zeamais). Due to the small size of amaranth seeds, this study postulated that amaranth grain can be blended with maize during storage to fill the intergranular spaces between maize kernels, reducing the overall void volume to minimize maize weevil movements to access the kernels, and thereby controlling the maize weevil population. The objective of this study was to investigate the effects on maize weevil control of blending maize with amaranth grain during storage versus storing maize alone. Three 208 L (55 gal) steel barrels were loaded with 160 kg (353 lb) of maize, and three were loaded with a maize-amaranth mixture (1:1 by volume), all with initial weevil populations of 25 live weevils per kg of maize. Blending maize with amaranth for storage reduced the number of live weevils after 160 days by 66% compared to storing maize alone. Additional reduction of live weevils could be accomplished if the maize were completely covered by amaranth grain, further restricting maize weevil access to the maize kernels. Keywords: Broken corn and foreign material, Insects, Insect infestation, Mechanical damage, Moisture content, Postharvest losses, Relative humidity, Temperature, Test weight.

Many experiences in engineering education boast positive gains to students' learning and achievement. However, current literature is less clear on the economic costs associated with these efforts, or methods for performing said analyses. To address this gap, we proposed a structured approach to analyzing the incremental costs associated with an experience in engineering education. This method was modeled after those found in medicine and early childhood education. We illustrated our methodology using marginal (above baseline) time and cost ingredients that were collected during the development, pilot, and steady-state phases of a mechatronic experience in a first-year undergraduate engineering technology course. Specifically, our method included descriptive analysis, Pareto analysis, and cost per capacity estimate analysis, the latter of which has received limited discussion in current cost analysis literature. The purpose of our illustrated explanation was to provide a clear method for incremental cost analyses of experiences in engineering education. We found that the development, pilot, and steady-state phases cost just over $17.1k (similar to$12.4k for personnel and similar to$4.7k for equipment), based on 2015 US$ and an enrollment capacity of 121 students. Cost vs. capacity scaled at a factor of - 0.64 (y = 3,121x(-0.64), R-2 = 0.99), which was within the 95% interval for personnel and capital commonly observed in the chemical processing industry. Based on a four-year operational life and a range of 20-400 students per year, we estimated per seat total costs to range from roughly $70-$470, with our mechatronic experience averaging just under $150 per seat. Notably, the development phase cost, as well as the robot chassis and microcontroller capital cost were the primary cost terms of this intervention.

Educational literature has long supported strong correlations between student motivation and academic success. STEM literature has more recently shown mechatronic experiences to have positive impacts on these constructs, albeit limited empirical grounding. Therefore, the purpose of this study was to conduct a pilot experiment to empirically quantify differences in undergraduate student motivation and academic success in a mechatronic vs. a non-mechatronic experience, as well as examine the correlation between student motivation and academic success in both groups. We used a quasiexperimental, non-equivalent control vs. treatment design to collect n = 84 responses from multiple sections of a single undergraduate course. The multivariate dependent variable of student motivation was measured using the Motivated Strategies for Learning Questionnaire’s motivational orientation items. Our multivariate dependent variable of academic success was based on final course grades, final project scores, and quiz scores. Using ANCOVA and differences of proportions, we found no statistical difference in motivational orientation—specifically value choices and expectancy beliefs—in the mechatronic vs. non-mechatronic experience. In contrast, statistically significant differences in project scores and final course grades were observed in the mechatronic experience group. Additionally, we found no significant correlation between student motivation and academic success. These results indicated that students in the mechatronic experience, while earning significantly higher grades, did not exhibit different levels of motivation, leading to no association between student motivation and academic success. Even so, future research is needed to further understand the nuanced dynamics of motivational orientation within a mechatronic experience.

The Midwestern U.S. landscape is one of the most highly altered and intensively managed ecosystems in the country. The predominant crops grown are maize (Zea mays L.) and soybean [Glycine max (L.) Merr]. They are typically grown as monocrops in a simple yearly rotation or with multiple years of maize (2 to 3) followed by a single year of soybean. This system is highly productive because the crops and management systems have been well adapted to the regional growing conditions through substantial public and private investment. Furthermore, markets and supporting infrastructure are highly developed for both crops. As maize and soybean production have intensified, a number of concerns have arisen due to the unintended environmental impacts on the ecosystem. Many areas across the Midwest are experiencing negative impacts on water quality, soil degradation, and increased flood risk due to changes in regional hydrology. The water quality impacts extend even further downstream. We propose the development of an innovative system for growing maize and soybean with perennial groundcover to recover ecosystem services historically provided naturally by predominantly perennial native plant communities. Reincorporating perennial plants into annual cropping systems has the potential of restoring ecosystem services without negatively impacting grain crop production and offers the prospect of increasing grain crop productivity through improving the biological functioning of the system.

Woodchip bioreactors are recognized as an effective best management practice in the Iowa Nutrient Reduction Strategy. This edge-of-field practice intercepts and removes NO3-N, thereby reducing the NO3-N concentration in file drainage before being discharged into surface water. Actual NO3-N load reductions realized by woodchip bioreactors are impacted by bioreactor size, hydraulic retention time (HRT), and denitrification efficiency. A typical woodchip bioreactor in Iowa may have 0.07% bioreactor area with respect to treatment area, 4-8 h HRT, and 43% mean denitrification efficiency. Here, we explored the potential of using electrically stimulated woodchip bioreactors to achieve greater NO3-N removal, and estimated the costs of this approach. Batch experiments were conducted to determine the denitrification efficiency of electrically stimulated and traditional woodchip bioreactors at different HRTs and current densities. The resulting data was used to model costs and denitrification efficiency in 75 scenarios, covering a range of bioreactor volumes, HRTs, current densities, and annual durations of electrical stimulation periods. For each scenario, we reported the estimated annual NO3-N load reduction and NO3-N removal cost. We found that electrically stimulated woodchip bioreactors may remove an additional 37-72% annual NO3-N load than a traditional woodchip bioreactor, but at the expense of higher NO3-N removal costs, which were increased by 138-194%.

This study investigates students’ conceptions of engineering at the beginning and end of their involvement in a National Science Foundation funded Graduate STEM Fellows in K-12 Education (GK-12) program. It examines whether students involved in the program exhibited greater conceptions of engineering from beginning to end, whether differences exist among males and females, and if students’ engagement and satisfaction with their Fellows affects growth in conceptions of engineering. Pre-survey and post-survey data were collected annually over four years from 1,522 participants in grades 7 and 8 who had a GK-12 Fellow. Statistical analyses indicated students gained significantly in their conceptions of engineering during a year of GK-12 involvement. Those with a second year benefitted more, and the initial conception of engineering gap that occurred between males and females was closed by the end of students’ involvement in GK-12. The greater the degree of student engagement and satisfaction with their GK-12 Fellows, the more accurate were their conceptions of engineering. This study suggests STEM-focused partnership programs may positively affect students’ career conceptions, and there is value in value placing resident scientists who can facilitate student engagement in classrooms. Recommendations to program coordinators are provided.

Diet influences health and poor diets drive up healthcare costs for individuals and society as a whole. Multiple governmental programs in the US have aimed to educate citizens about diet choices, resulting in documented successes, as well as, unintended consequences such as increased food waste. Here we examine some of the relationships between healthy diets, food prices, and wealth by drawing parallels between the diffusion of technological innovation and healthy food diets. We introduce a simple modeling framework to estimate the adoption rates of healthy diets based on income and food prices, and describe the implications of the modeling results for the food industry and for government.

In the 2013-14 academic year, we embarked on an effort to flip two engineering courses in our department – a year-1 problem solving and programming course (Y1PS), and a year-3 numerical methods course (Y3NM). Initially, the Y3NM course, which we were also teaching for the first time and revising significantly as we did, was conducted in a standard flipped model wherein students viewed video lectures and took diagnostic quizzes prior to attending class, and where class time itself focused on discussion and problem solving. In contrast, based on our significant prior experiences teaching the Y1PS course, and upon its organization as a mixed-mode lecture/problems solving course, we did not take a standard flipped approach to it. Instead, in the Y1PS course, students watched videos during the class periods themselves; such a structure was facilitated by the classroom having one computer per student, to accommodate the programming portion of the class. We refer to this “watch in class” model as a hybrid-flipped classroom, and have found this approach to work significantly better in terms of student engagement and learning than the standard flipped model did for us. With that experience, we modified the Y3NM class to the hybrid-flipped model in subsequent offerings. We recognize that the hybrid-flipped model is resource intensive because it requires far more classroom technology than traditional lecture, and also that our positive results are in part due to the computer-intensive nature of both courses in which we have implemented this model. We report here about our experiences, both positive and negative, with flipped and hybrid-flipped approaches, and provide guidance for instructors considering such changes themselves.

The effect of batch thermosonication at 20 kHz on plasmin activity in skim milk, stored up to 49 days, was studied. The influence of sonication time was evaluated by heating samples to 72 degrees C for 15 s, followed by sonication at 72 degrees C, at a constant amplitude of 170 mu m(peak-to-peak (p-p)) for 10, 30, or 60 s. The influence of temperature was evaluated by sonicating samples for 60 s at 15, 30, 45, 60 and 75 degrees C at constant amplitude. Plasmin activity of treated as well as raw and heated control samples were analyzed on days 7, 21, 35, and 49. At all three times tested, thermosonication significantly decreased the plasmin activity compared to the raw and heated controls, with plasmin activity being reduced by over 90% after the 60 s treatment. Across the evaluated temperature range, samples that were thermosonicated displayed lower plasmin activity than their counterparts that were heated without sonication.

Here we report on a static, algebraic, spreadsheet-implemented modeling approach to estimate the costs, energy inputs and outputs, and global warming potential of biomass feedstocks. Inputs to the model included literature sourced data for: environmental factors, crop physiological-parameters such as radiation use efficiency and water use efficiency, and crop cost components. Using an energy-input-output life-cycle-assessment approach, we calculated the energy associated with each cost component, allowing an estimate of the total energy required to produce the crop and fuel alongside the energy return on investment. We did this for crop scenarios in the upper Midwest US and Far West US (for algae). Our results suggested that algae are capable of the highest areal biomass production rates of 120 MG/(ha·a), ten times greater than Maize. Algal fuel systems had the highest costs, ranging from 28 to 65 US $/GJ, compared to 17 US $/GJ for Maize ethanol. Algal fuel systems had the lowest energy returns on investment, nearly 0, compared to 25 for Switchgrass to ethanol. The carbon equivalent emissions associated with the production schemes predictions ranged from 40 (Maize) to 180 (algae PBR) CO2eq/GJnet. The promise of low cost fuel and carbon neutrality from algae is demonstrated here to be extremely challenging for fundamental reasons related to the capital-intensive nature of the cultivation system.