Grass2Gas Datasets

Ammonia emissions and corn yield response from injected versus surface‐applied liquid‐separated anaerobic digestate

Anaerobic digestion and digestate solid-liquid separation are manure treatment strategies used on commercial dairy farms. These treatment strategies typically result in increased total ammoniacal nitrogen concentration (TAN) and pH, and reduced dry matter content, which tend to increase ammonia (NH3) emissions following field application. We hypothesized that shallow disk injection of liquid-separated, anaerobically digested dairy manures, compared to surface application without incorporation on no-till farmland, would reduce NH3-N emissions and conserve manure-N for crop production. Six corn (Zea mays L.) silage studies were established on commercial dairy farms across Pennsylvania in 2021-2023 with side-by-side field-scale treatment comparison strips replicated five times per farm. We quantified the impact of liquid-separated, anaerobically digested manure application methods on: i) NH3 emissions for 24 hours after application, ii) in-season soil nitrate-N, iii) cornstalk nitrate at harvest, iv) corn silage production, and iv) returns on investment.

Bio-oil aqueous phase as a laccase inducer in Pleurotus ostreatus: Laccase properties and applications

The aqueous phase (AP) generated through biomass pyrolysis is commonly regarded as a waste stream, as its dilute and toxic properties pose a challenge towards its valorization. This study investigated the prospects of using AP as an inducer for laccase production from white-rot fungi. Experimental results show AP addition resulted in a 7- and 2.9-fold increase in laccase production relative to no inducer and a copper inducer, respectively. By adding copper and AP together, a laccase yield of 954.5 U/g was obtained. The AP-induced laccase was further evaluated for various applications. Alone, the laccase was effective in decolorizing coomassie blue dye, increasing saccharification yield from prairie biomass, and in detoxifying tetracycline. When AP was used as a laccase mediator, the laccase was also capable of decolorizing crystal violet dye, showing that AP not only induces laccase production, but can also mediate certain reactions. Overall, these findings suggest that laccase production could be a promising method of valorizing AP.

Data for: Modeling Ecosystem Services of Managed Prairie Systems: Simulating Production and Nitrate Loss

These data are measurements of plant species and nutrient composition for fertilized and unfertilized prairie ecosystems recorded at a long-term experiment (15-years) near Ames, Iowa, United States. We measured the plant species composition using a point-intercept method, recording species throughout the plot to determine overall species composition for each treatment. Additionally, we collected biomass samples and used an Organic Elementar Vario Micro Cube analyzer to determine the plant nutrient makeup of different grass species found in prairie ecosystems. These data provide insight into the make-up of prairie agro-ecosystems which can be used for further research and modeling efforts.

Data for: Techno-economic and environmental assessment of converting mixed prairie to renewable natural gas with co-product hydroxycinnamic acid, Iowa, USA, 2022-2023.

This dataset compiles model outputs, parameter sets, and documentation supporting a techno‑economic analysis (TEA) and life‑cycle assessment (LCA) of co‑digesting beef cattle manure with pretreated mixed prairie biomass to produce renewable natural gas (RNG), with hydroxycinnamic acids (HCA) and digestate‑derived biochar co‑products. It accompanies the study by Katherine Wild, Elmin Rahic, Lisa A Schulte Moore, and Mark Mba Wright "Techno-economic and environmental assessment of converting mixed prairie to renewable natural gas with co-product hydroxycinnamic acid," in Biofuels, Bioproducts, & Biorefining, 2024. The integrated simulation and assessment framework quantifies process performance, economics, and greenhouse‑gas intensity across five scenarios representing combinations of alkaline‑ethanol pretreatment for HCA extraction, liquid recirculation fractions, and biochar addition. This data collection includes: stream‑level mass flow/composition tables for each scenario; RNG, biochar, and HCA annual production summaries; literature‑based methane/biogas yield benchmarks; equipment‑level capital costs; TEA assumptions; emission‑factor inventories and displacement credits; and full sensitivity/uncertainty matrices for MFSP and GWP.

Hydroxycinnamic acid extraction from prairie biomass for enhancing performance in anaerobic digestion

This study explores the hydroxycinnamic acid extraction from prairie biomass as a potential value-added pretreatment for enhancing the performance of anaerobic digestion. Pretreatment increased the biomethane potential of prairie biomass by 33%; when the extraction residue was left on the biomass, the biomethane potential increased by 100%. When the treated biomass was co-digested with manure, a 134% and 25% increase in methane productivity and methane content was obtained, respectively, relative to raw biomass co-digested with manure. Hydroxycinnamic acid extraction also improved anaerobic digestion performance under biochar supplementation and liquid digestate recirculation conditions. Lastly, the extraction process was optimized for hydroxycinnamic acid yield. It was found that increases in treatment temperature and time could further increase yield by 5%. Collectively, the results show hydroxycinnamic acid extraction can be used as a highly effective pretreatment for improving the anaerobic digestion of prairie biomass.

Integrated experimental and techno-economic modeling of RNG production from prairie biomass

This study coupled experimental and techno-economic modeling to evaluate the economic prospects of utilizing prairie biomass as a feedstock for anaerobic digestion. In addition to evaluating key anaerobic digestion parameters, four scenarios were evaluated investigating liquid digestate recirculation, as well as methane recovery from the liquid digestate in a two-stage anaerobic digestion process.

Laccase TEA experimental data

Laccase fermentation was conducted by cultivating white-rot fungi (Pleurotus ostreatus) on prairie biomass (growth phase), followed by the induction of laccase using bio-oil aqueous phase (induction phase). This fermentation process was modeled for techno-economic analysis based on experimental data. The experimental data consisted of two parts: 1) optimizing nitrogen concentration for the growth phase, and 2) modeling laccase production and induction phase time using response surface methodology by varying substrate bed depth, substrate to inoculum ratio, and growth phase length.

Manure application method and timing with cover crops effect on N2O emissions

Ammonia (NH3) loss following manure application is an environmental concern and N loss for crop production. Manure injection typically reduces NH3 loss compared to surface application without incorporation but increases emissions of nitrous oxide (N2O) a potent greenhouse gas. Synchronizing manure in spring with cover crop (CC) growth may increase N recovery and reduce N2O emissions compared to applying manure later in the absence of growing crops. We compared two manure application methods: shallow-disk injection (IM) or surface banding without incorporation (BM) to annual ryegrass (Lolium multiflorum L.) and red clover (Trifolium pratense L.) CC at two times: early spring on growing CC (EARLY) or late spring on terminated CC (LATE). The randomized split-plot block experiment was conducted at Rock Springs, PA, during 2021-2022. After manure application, we measured NH3 for 72 hours and N2O throughout the growing season. Aboveground CC biomass, N, and C:N ratio; pre-sidedress soil nitrate, corn (Zea mays L.) stalk nitrate and silage yield were assessed. Averaged across application times, compared to BM, IM reduced cumulative NH3 loss, increased soil N, resulted in 13% greater corn yield but increased yield-scaled N2O. Compared to BM LATE, BM EARLY reduced NH3 loss 43%, increased CC N, reduced N2O emission 50%, but decreased corn yield 11%. When IM was EARLY compared to LATE, CC N increased 84%, cumulative N2O loss decreased 55%, and corn yield was similar. Injecting manure to growing cover crops offers a strategy for reducing detrimental NH3 and N2O emissions and maintaining corn yield.

Optimization of Solid-State Anaerobic Digestion of Prairie Biomass and Beef Manure

This dataset supports the evaluation and optimization of solid-state anaerobic digestion (SSAD) using prairie biomass and beef manure mixtures under varying total solids (TS) contents, particle sizes, and percolation frequency. It includes raw and processed data on biogas and methane production, volatile solids composition, carbon-to-nitrogen ratios, theoretical biochemical methane potential (BMP), energy balances, and water activity.

Optimizing targeted conservation for disproportionate benefits

The U.S. Corn Belt is highly productive with respect to agricultural outcomes, but has unintended negative impacts on the water quality and biodiversity. Perennial conservation practices provide multiple benefits that can effectively mitigate many environmental challenges when strategically integrated within agricultural landscapes. Many conservationists and land use planners are turning to spatially targeted conservation, which can help conservation partners focus time and resources on the most vulnerable areas and plan for the joint alignment of environmental and economic outcomes. Our objective was to demonstrate a methodology for optimizing the placement of perennial conservation practices—including prairie strips, riparian buffers, and nutrient-removal wetlands—across agricultural landscapes.
We sought to cost-effectively maximize multiple environmental outcomes and understand the economic impacts of optimal conservation practice adoption in East Big Creek watershed, located in central Iowa. We used open source data and tools to inform the placement of perennial conservation practices and maximize watershed scale water quality (nitrate-nitrogen reduction) and biodiversity across a range of conservation practice annual cost constraints, and determined the regional economic impact of optimal conservation practice adoption. The optimization algorithm revealed landscape configurations that met the range of budget constraints. Reduction in watershed-level nitrate-nitrogen loss by 14% and improvements to biodiversity by 54% can be achieved by shifting as little as 1.3% of agricultural land use when perennial conservation practices were strategically chosen and placed. The initial establishment of perennial conservation practices generated substantial additional economic activity in comparison to the status quo, including the addition of $932-$5,550,000 in total agricultural-related industrial output, $447-$3,100,000 in total value added, $310-$2,400,000 in total labor income, and up to 42 jobs. Few studies have incorporated spatial optimization of conservation practice placement and also determined the overall economic impacts of alternative landscape configuration. Our study demonstrates a methodology that can be incorporated into planning tools to inform cost-effective multi-objective conservation action.

Prairie manure application impacts on floral abundance, plant growth, plant community structure, insect and spider community abundance and activity density

The objective of this study was to apply different rates of dairy manure to diverse, native, perennial plant communities (i.e., prairie strips) and evaluate the impacts on floral abundance, plant growth, plant community structure, insect and spider community abundance and activity density. This experiment took place at the Iowa State University's Horticulture Research Station in Ames, Iowa and was replicated at two different sites, one in a tilled agricultural field and one in an established tallgrass prairie. Varying amounts and frequencies of liquid dairy manure from the ISU Dairy Farm was applied topically to the ground surface and plant and insect data were collected. Insects (referring to order Insecta and class Arachnida) were collected using pitfall traps and insect vacuums. This data package is completed.

Soil organic carbon and nutrient dynamics in response to anaerobic digestate application to farm fields

This dataset documents a long-term, field-scale study of anaerobic digestate application on commercial croplands in eastern Iowa, USA. It includes detailed records of digestate composition, application rates, and timing, as well as soil test results collected over a 12-year period (2011–2023) from 14 agricultural fields. The dataset supports analysis of soil organic carbon (SOC), nutrient dynamics, and isotopic composition in response to digestate inputs. It contains 421 geo-referenced soil samples, digestate nutrient profiles, field management histories, and spatial boundaries. The data were collected as part of a collaborative effort between researchers at Iowa State University and Sievers Family Farms to evaluate the agronomic and environmental implications of integrating anaerobic digestion into row crop and livestock systems.

Techno-economic analysis of biogas upgrading

Water scrubbing is a physical absorption method which uses absorption to remove impurities from biogas. The feasibility of water scrubbing to upgrade biogas was analyzed for two fluids (tap water and digestate liquid), and in two settings (U.S and Nigeria). Experiments were carried out to test the absorption capacity of carbon dioxide using these fluids. A techno-economic model was created to simulate the performance of a biogas upgrading system, and the model was used to estimate the viability of the system.

Results indicate that biogas upgrading for a small-scale farm in Pennsylvania yields a negative net present value (NPV) of -$795,246, with all but the most optimistic scenario producing negative values. Sensitivity analysis indicates that pipeline cost, number of cows, and biogas production costs have the greatest impact on NPV, while utility costs have the least influence.

Digestate liquid can be used to absorb carbon dioxide; however, its performance is lower than that of water. It was found to be most effective at 4°C and 1440 minutes. The techno-economic analysis of using digestate liquid for upgrading also results in a slightly improved but still negative NPV (-$65,240), compared to using water, despite no associated cost for the liquid. This outcome can be attributed to the required height of the column, which is approximately twice the height needed when using water to achieve the same carbon dioxide removal efficiency.

Techno-economic analysis of biogas upgrading in Nigeria using biomethane as a substitute for liquefied petroleum gas (LPG), with a base case of 60 cows, also yields a negative NPV of -N10,253,874, only the most optimistic variations of this scenario result in a positive NPV. While the NPV of these systems tends to be negative, their use may be justifiable in favorable settings and conditions. Sensitivity analysis shows that the biogas production cost has the greatest impact on NPV, followed by compressed biomethane cost and the number of cows. However, biogas production costs could be reduced through funding incentives, grants, and financing mechanisms. The farming system in Nigeria also affects the availability of manure, as cows are not typically confined to a single location.

Overall, this thesis provides an assessment of the economic and technical feasibility of biogas upgrading using water and digestate liquid in two different continents, showing the significant variables assessing the adoption of the use of biomethane as electricity, renewable natural gas or liquified petroleum.

Valuing multiple ecosystem services under contrasting land use scenarios

While provisioning ecosystem services generated through agricultural production are high, this often comes at the expense of other ecosystem services. Approaches that support both farm income and a balanced array of ecosystem services are needed. We employed a landscape modeling approach to demonstrate the financial and ecosystem service outcomes of strategically restoring grassland cover within a Corn Belt agricultural watershed. We assessed potential changes associated with a “Baseline” land use scenario and two alternative scenarios for the Grand River Basin (Iowa and Missouri, USA). In a “Buffered” scenario we simulated the impacts of replacing cropland within 20 m of streams with restored native grassland cover. In a “Productivity-based” scenario we simulated the replacement of annual row crops on poorly performing croplands with native grassland cover. Grasslands comprised 0.4% of the Baseline scenario. Grassland was expanded to 0.8% of the watershed in the Buffered scenario, reducing annual nutrient and sediment loss by 1.44%, increasing soil carbon sequestration by 0.12% over 10 years, and increasing pollinator abundance by 0.01%. The estimated annual value of these enhancements was $1.7 million for nitrogen reduction, $0.1 million for phosphorus reduction, $0.5 million for sediment reduction, and $1.3 million for soil carbon sequestration. Grassland comprised 4.9% of the watershed in the Productivity-based scenario, reduced annual nutrient and sediment loss by 11.50%, increased soil carbon sequestration by 1.13% over 10 years, and increased pollinator abundance by 0.42%. The estimated annual value of enhancements was $18 million for nitrogen reduction, $1.4 million for phosphorus reduction, $2.5 million for sediment reduction, and $14 million for soil carbon sequestration. We also calculated the value of grassland biomass for a potential energy market. The benefit of producing and selling grassland biomass ranged -$445 to $1,291 ha−1 yr−1. Scaled to the watershed, annual revenues ranged -$7.3 million to $21.1 million for the Buffered scenario and -$44.2 million to $128.8 million for the Productivity-based scenario. This study was the first to quantify changes in revenue and the value of ecosystem services associated with grassland restoration in the Grand River Basin and can help inform discussion among watershed stakeholders.