Facilitating Spaces of Urban Agroecology: A Learning Framework for Community-University Partnerships

At the local scale in Minneapolis/St. Paul (MSP), MN, urban farms, community gardens, and home gardens support diverse individual and community goals, including food access and sovereignty, recreation and outdoor activity, youth education, and racial, economic, and environmental justice. Collaborations between urban growers, policymakers, scholars, and communities that leverage urban farms and gardens as sites of ecological, social, and political transformation represent spaces of urban agroecology. Participatory research can play a vital role in urban agroecology by facilitating integration of science, movement, and practice, but frameworks to accomplish this are still emerging. This paper, therefore, proposes a “learning framework” for urban agroecology research that has emerged from our community-university partnership. We—a group of growers, community partners, and researchers—have worked with each other for 5 years through multiple projects that broadly focused on the socio-ecological drivers and impacts of urban farms and gardens in MSP. In fall 2019, we conducted our first formal evaluation of the participatory processes implemented in our current project with the objectives to (1) identify processes that facilitated or were barriers to authentic collaboration and (2) understand the role of relationships in the participatory processes. Qualitative surveys and interviews were developed and conducted with researchers, partners, and students. Analysis revealed that urban agroecology research provided a space for shared learning, which was facilitated through co-creation of research, embodied processes, and relationships with people, cohorts, and place. As part of our partnership agreements, we as researchers wrote this article—in close consultation with partners—to share this framework in the hopes that it will serve as a model for other research collaborations working within complex urban agroecological systems

Long-term recovery of soil carbon stocks and permafrost depth lags recovery of organic layer thickness following fire in black spruce forests of the Copper River Basin, Alaska

This study investigated differences in forest structure, organic layer thickness, soil organic carbon, and permafrost depth between late successional (LS) and post fire (PF, 90 to 120 years since burn) plots under black spruce (Picea mariana (Mill.) BSP) on fine-textured, poorly drained lacustrine sediments in the Copper River Basin, Alaska. We found that although live stem and seedling density and organic layer thickness (OLT) was not significantly different between PF and LS plots (28 7 cm and 31 10 cm, respectively), soil organic carbon (SOC) stocks (30 10 kg m-2 and 46 12 kg m-2, respectively), and permafrost depth (90 28 cm and 56 12 cm, respectively) remain significantly different. OLT was linearly related to 1 m SOC stocks for LS plots but not for PF plots, and LS plots had a greater proportion of highly decomposed (humic) material in the organic layer. Soil properties on PF plots appear to be on a trajectory of recovery towards LS plots with respect to SOC stocks, permafrost depth, and organic layer composition, but remain different despite nearly 100 years since fire disturbance and therefore potentially sensitive to changes in future fire frequency or climate.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Meteoric Beryllium-10 as a Tracer of Erosion Due to Postsettlement Land Use in West-Central Minnesota, USA

© 2019. American Geophysical Union. All Rights Reserved. Meteoric beryllium-10 ( 10 Be m , t 1/2  = 1.4 Myr) is a cosmogenic radionuclide that remains largely underutilized for deriving hillslope-scale estimates of erosion on uplands under conditions of land use change. We applied two different models for estimating erosion rates from observed 10 Be m concentrations (a one-dimensional model predicting vertical profiles of 10 Be m within hillslope soils [loss only, diffusion only, LODO] and a two-dimensional model predicting the concurrent evolution of hillslope topography and 10 Be m distributions via bioturbation, chemical mobility, and surface erosion [Be2D]). Both models were used to derive pre-European and post-European settlement erosion rates (E nat and E post , respectively) across paired cultivated and uncultivated hillslopes in west-central Minnesota, USA. E post estimates from 10 Be m were compared to E post estimates derived from 137 Cs inventories and the process-based Water and Tillage Erosion Model (WaTEM). The results from these models suggest that erosion rates from upper positions on the cultivated hillslope have increased from an average of 0.047 mm/year under natural conditions to E post values of 3.09 mm/year. The Be2D and LODO models, on average, produced E post estimates that were similar in magnitude to WaTEM and 137 Cs conversion models. This numerical convergence does not imply absolute 10 Be m model accuracy, particularly when considering the uncertainties inherent in each approach, but it does suggest that the orders of magnitude increase in estimated erosion rates from E nat to E post is robust. Additionally, the pattern of E post estimates produced using 10 Be m conversion models is supported by the distribution of soil inorganic carbon at the study site. Our results demonstrate that 10 Be m can provide reasonable estimates of both predisturbance and postdisturbance erosion rates in landscapes that have undergone extensive human modification.status: publishe

Jumble judging: Cognitive and affective outcomes of intercollegiate collaboration at a soil judging competition

Student-student interactions are influential parts of field experiences. While competitive judging events are a fun way to engage students in field-based learning, the focus on competition leads to an atmosphere that discourages collaboration between students. The objective of this study was to evaluate the cognitive and affective learning outcomes resulting from intercollegiate collaboration at a soil judging competition. Teams with students from two to three different universities were assigned and referred to as jumble judging teams. Jumble judging was held for the first time in the 2021 Region 5 Collegiate Soil Judging Contest. Learning outcomes were assessed using a pre- and post-survey, as well as group and individual reflections completed in the field. Student responses were generally positive, with 70% of students expressing agreement or strong agreement that they would like jumble judging to be included in future contests, 54% citing jumble judging as one of the best parts of the contest, and 93% identifying learning outcomes or describing an affective learning experience resulting from jumble judging. Evidence of both cognitive and affective learning were identified through student surveys and reflections. Overall, the event created a collaborative and collegial atmosphere and increased interaction between students from different universities, while maintaining the competitive nature of the event that motivates many students to get involved with judging teams.This is a manuscript of an article published as Young, Rebecca A., Judith K. Turk, Nicolas A. Jelinski, Amber D. Anderson, Kerry M. Clark, Ashlee Dere, Colby J. Moorberg, Kristopher Osterloh, and DeAnn Presley. "Jumble judging: Cognitive and affective outcomes of intercollegiate collaboration at a soil judging competition." Natural Sciences Education: e20104. doi:10.1002/nse2.20104. Posted with permission

Iron mineral structure, reactivity, and isotopic composition in a South Pacific Gyre ferromanganese nodule over 4Ma

International audienceDeep-sea ferromanganese nodules accumulate trace elements from seawater and underlying sediment porewaters during the growth of concentric mineral layers over millions of years. These trace elements have the potential to record past ocean geochemical conditions. The goal of this study was to determine whether Fe mineral alteration occurs and how the speciation of trace elements responds to alteration over ∼3.7 Ma of marine ferromanganese nodule (MFN) formation, a timeline constrained by estimates from 9Be/10Be concentrations in the nodule material. We determined Fe-bearing phases and Fe isotope composition in a South Pacific Gyre (SPG) nodule. Specifically, the distribution patterns and speciation of trace element uptake by these Fe phases were investigated. The time interval covered by the growth of our sample of the nodule was derived from 9Be/10Be accelerator mass spectrometry (AMS). The composition and distribution of major and trace elements were mapped at various spatial scales, using micro-X-ray fluorescence (μXRF), electron microprobe analysis (EMPA), and inductively coupled plasma mass spectrometry (ICP-MS). Fe phases were characterized by micro-extended X-ray absorption fine structure (μEXAFS) spectroscopy and micro-X-ray diffraction (μXRD). Speciation of Ti and V, associated with Fe, was measured using micro-X-ray absorption near edge structure (μXANES) spectroscopy. Iron isotope composition (δ56/54Fe) in subsamples of 1–3 mm increments along the radius of the nodule was determined with multiple-collector ICP-MS (MC-ICP-MS). The SPG nodule formed through primarily hydrogeneous inputs at a rate of 4.0 ± 0.4 mm/Ma. The nodule exhibited a high diversity of Fe mineral phases: feroxyhite (δ-FeOOH), goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and poorly ordered ferrihydrite-like phases. These findings provide evidence that Fe oxyhydroxides within the nodule undergo alteration to more stable phases over millions of years. Trace Ti and V were spatially correlated with Fe and found to be adsorbed to Fe-bearing minerals. Ti/Fe and V/Fe ratios, and Ti and V speciation, did not vary along the nodule radius. The δ56/54Fe values, when averaged over sample increments representing 0.25–0.75 Ma, were homogeneous within uncertainty along the nodule radius, at −0.12 ± 0.07‰ (2sd, n = 10). Our results indicate that the Fe isotope composition of the nodule remained constant during nodule growth and that mineral alteration did not affect the primary Fe isotope composition of the nodule. Furthermore, the average δ56/54Fe value of −0.12‰ we find is consistent with Fe sourced from continental eolian particles (dust). Despite mineral alteration, the trace element partitioning of Ti and V, and Fe isotope composition, do not appear to change within the sensitivity of our measurements. These findings suggest that Fe oxyhydroxides within hydrogenetic ferromanganese nodules are out of geochemical contact with seawater once they are covered by subsequent concentric mineral layers. Even though Fe-bearing minerals are altered, trace element ratios, speciation and Fe isotope composition are preserved within the nodule

Jumble judging: Cognitive and affective outcomes of intercollegiate collaboration at a soil judging competition

Student–student interactions are influential parts of field experiences. While competitive judging events are a fun way to engage students in field-based learning, the focus on competition leads to an atmosphere that discourages collaboration between students. The objective of this study was to evaluate the cognitive and affective learning outcomes resulting from intercollegiate collaboration at a soil judging competition. Teams with students from two to three different universities were assigned and referred to as jumble judging teams. Jumble judging was held for the first time in the 2021 Region 5 Collegiate Soil Judging Contest. Learning outcomeswere assessed using a pre- and postsurvey, as well as group and individual reflections completed in the field. Student responses were generally positive, with 70% of students expressing agreement or strong agreement that they would like jumble judging to be included in future contests, 54% citing jumble judging as one of the best parts of the contest, and 93% identifying learning outcomes or describing an affective learning experience resulting from jumble judging. Evidence of both cognitive and affective learning were identified through student surveys and reflections. Overall, the event created a collaborative and collegial atmosphere and increased interaction between students from different universities, while maintaining the competitive nature of the event that motivates many students to get involved with judging teams

Assessing the sensitivity and repeatability of permanganate oxidizable carbon as a soil health metric: An interlab comparison across soils

Soil organic matter is central to the soil health framework. Therefore, reliable indicators of changes in soil organic matter are essential to inform land management decisions. Permanganate oxidizable carbon (POXC), an emerging soil health indicator, has shown promise for being sensitive to soil management. However, strict standardization is required for widespread implementation in research and commercial contexts. Here, we used 36 soils—three from each of the 12 USDA soil orders—to determine the effects of sieve size and soil mass of analysis on POXC results. Using replicated measurements across 12 labs in the US and the EU (n = 7951 samples), we quantified the relative importance of 1) variation between labs, 2) variation within labs, 3) effect soil mass, and 4) effect of soil sieve size on the repeatability of POXC. We found a wide range of overall variability in POXC values across labs (0.03 to 171.8%; mean = 13.4%), and much of this variability was attributable to within-lab variation (median = 6.5%) independently of soil mass or sieve size. Greater soil mass (2.5 g) decreased absolute POXC values by a mean of 177 mg kg−1 soil and decreased analytical variability by 6.5%. For soils with organic carbon (SOC) >10%, greater soil mass (2.5 g) resulted in more frequent POXC values above the limit of detection whereas the lower soil mass (0.75 g) resulted in POXC values below the limit of detection for SOC contents −1 while decreasing the analytical variability by 1.8%. In general, soils with greater SOC contents had lower analytical variability. These results point to potential standardizations of the POXC protocol that can decrease the variability of the metric. We recommend that the POXC protocol be standardized to use 2.5 g for soils <10% SOC. Sieve size was a relatively small contributor to analytical variability and therefore we recommend that this decision be tailored to the study purpose. Tradeoffs associated with these standardizations can be mitigated, ultimately providing guidance on how to standardize POXC for routine analysis.</p