Despite the rapid expansion of urban agriculture at local, regional and national scales, unique challenges to urban agricultural operations remain unresolved. In the Twin Cities Metropolitan Area (TCMA), Minnesota, urban growers remain challenged by issues related to land access, high public visibility, and the perceived trade-offs between agricultural land use and other, more traditional forms of urban land use. Thus, a data-driven approach to evaluating the ecosystem services provided by urban agricultural best management practices will play a critical role in informing the decisions of policy-makers and providing sustainable outcomes for urban farmers, whose specific management practices and challenges often go overlooked by traditional agricultural research and extension activities. Our team of researchers, farmers and community organizations is uniquely poised to address this need through integrated on- and off- farm collaborative research. Our on-farm approach involves the evaluation of soil quality, water quality and quantity, biological diversity and crop yields at multiple scales for urban agricultural best management practices implemented by our farmer-partners. This is paired with an off-farm replicated approach implemented by our academic partners to allow rigorous comparative data collection without imposing additional constraints on space-limited urban agricultural operations. The expected outcomes of this work include the production of scientific information which can be utilized by policy-makers and farmers to enhance the economic and environmental sustainability of urban agriculture, and the development of a long-term collaborative and information sharing framework which improves outcomes for urban agriculture in the Twin Cities.
The action outcomes of this project align with three project aims: (1) 3 large-scale urban farms and 20 community gardens will use results from our evaluation of ecosystem services to improve amendment practices, yield, and resource protection, (2) policy-makers will be empowered to make data-driven decisions regarding the current and potential land base and ecosystem services from urban agriculture, and (3) networks of communication through academic, farmer and community partners will be strengthened and the Twin Cities urban agriculture community will have an increased number of communication tools for shared information exchange.
The carefully cultivated University-community partner relationships leveraged in this project are the result of more than 2 years of preparatory meetings, preliminary efforts, and collaborative discussions. A UMN OVPR-funded working group brought together community partners and academic collaborators from three institutions (including myself, Dr. Mary Rogers – Horticulture, University of Minnesota; Dr. Chip Small – St. Thomas University; and Dr. Valentine Cadieux – Hamline University) and began with a Sustainable Food Systems colloquia in December of 2015, and culminated in the first annual “Twin Cities Urban Agriculture Workshop” in October, 2016. This working group met quarterly, received input from farmers, growers, and community members; and consolidated the needs for research and education on urban agriculture in the Twin Cities.
These foundational efforts led to the establishment of a network of academic and community collaborators who worked together on a preliminary project in 2016 to develop a framework of mutual trust and respect. During this preliminary work, significant time was spent building relationships, understanding the needs and expectations of community partners, and jointly developing a road map for future on- farm research.
There is a need for a local, data-driven evaluation of ecosystem services provided by urban agricultural (UA) land use to maximize the benefit from proposed land use strategies (Pulighe et al., 2016). Although the provisioning service of food production is often evaluated as one of the most tangible benefits of UA (McClintock et al., 2013), this represents just one component in a highly diverse array of ecosystem services potentially provided by UA (Calvet-Mir et al., 2012). Database searches of the peer-reviewed literature reveal a significant bias towards research on ecosystem services provided by agriculture in rural areas (e.g. Smukler et al., 2012), which is important because UA is significantly different from peri-urban or rural agriculture in several ways. UA tends to rely heavily on intensive inputs of locally-derived materials, and the repeated application of these amendments has been shown to dramatically increase soil quality and vegetable crop yields in degraded areas (Beniston et al., 2016). Additionally, UA typically occurs within a matrix of highly urbanized, low-diversity land-uses dominated by impervious surfaces, making the ecosystem services resulting from UA even more critical, and in proximal vicinity to larger populations which could benefit from those services (Richardson and Moskal, 2016). Urban agricultural land uses have the potential to generate a high degree of synergy among ecosystem services and thus provide significant benefits to urban populations relative to competing land uses such as vacant lots or turfgrass (Bennett et al., 2009). Several studies have investigated other aspects of provisioning, regulating, supporting and cultural services from UA, but few have done so holistically, and none in cold climates analogous to the TCMA.
This work evaluates and quantifies a suite of ecosystem services provided by UA in the TCMA and includes a suite of regulating, supporting and cultural services in addition to the provisioning service of crop yields. A broader, more holistic perspective on these services will lead to better, more informed decisions by policy-makers regarding the benefits of UA in the TCMA.
The approach to ecosystem services assessment in this study is underpinned by integrated on- and off-farm data collection at both plot and site scales. The off-farm replicated plots allow us to connect and extend on-farm observations (which are necessarily smaller in scale, limited in treatment, and more variable) to additional crop functional types and treatments. For the on-farm component, we utilize a well-developed, highly collaborative, and integrated network of for-profit (Growing Lots – Minneapolis), non-profit (Frogtown Farm – St. Paul & Mashkikii Gitigan – Minneapolis), and community garden (Urban Farm and Garden Alliance – St. Paul) growers who have agreed to provide space for replicated studies (see letters of support attached). We will then contrast these urban agricultural management plots with turfgrass and unmanaged vacant lots – the two most probable open-space alternative land uses to UA in the TCMA and other cities (McClintock et al., 2013). Methodological details of this data collection are provided below to demonstrate the scale and depth of data which will be available for the proposed CURA-funded quantitative ecosystem services assessment.
On-Farm Data Collection: At each partner site, we will establish triplicate plots (1m2) in the 2018 growing season to evaluate three urban agricultural management practices: (1) No amendment, (2) Compost amendment = single source municipal food waste compost, high application rate based on crop nitrogen (N) demand – using the ATTRA compost rate calculator, and (3) a “Growers Choice” practice (which partners will use to leverage the data collected in the project to explore questions of their own). Each on-farm plot will be planted with collards (chosen because all partners could agree on this as a valuable crop for their operation). The data emerging from the evaluation of these practices will be compared to “reference” land use data collected from plots on vacant lots and unmanaged (or mown only) turfgrass – either on-farm, adjacent to farms, in open space/boulevards, or in the surrounding neighborhood.
Off-Farm Data Collection: Dr. Chip Small (St. Thomas University) and I are integrating the off-farm and on-farm research design by collaboratively assessing replicated plots at the St. Thomas University (St. Paul, MN) Stewardship Garden. These consist of 36 separate 4m2plots, with each 1m2quadrant planted to a different vegetable crop functional type (Bell Peppers, Bush Beans, Carrots, and Collards), under 6 different treatments of (1) single source municipal food waste compost – low rate, based on crop phosphorus (P) demand, (2) single source municipal food waste compost – high rate, based on crop N demand, (3) no amendments, (4 & 5) reserved for replication of “Growers Best” practices, and (6) established turfgrass, with 6 replicates per treatment.
Metrics of provisioning services: Crop yields and plant quality. For on-and off-farm plots, crop and biomass yields (both edible portions and total biomass) will be measured at the time of harvest. Our approach to yield evaluation at the site scale will follow recommended protocols informed by previous work funded by the CURA Kris Nelson Community-Based Research Program (Grewell, 2015). Plant quality for both on-and off-farm collard plots will be assessed through triplicate tissue samples two times during the growing season (mid-July, September) by foliar nitrate and chlorophyll measurements.
Metrics of regulating services: Soil quality, water quality, infiltration, and gas fluxes. Soil quality assessments will be conducted by measuring parameters relevant to plant growth, water movement and nutrient cycling, including:
- Soil chemical properties (organic carbon, pH, nitrate, ammonium, available P and exchangeable potassium (K),
- Soil physical properties (bulk density, soil texture, aggregate stability, infiltration, and hydraulic conductivity), and
- Soil biological properties (microbial community phospholipid fatty acids and extracellular enzymes).
These will be measured prior to the establishment of plots and once each year thereafter at three depth increments (0-4″, 4-8″ and 8-12″) in each plot. Prior to plot establishment, lysimeters (which collect soil pore water under conditions of saturated flow) will be installed at 12″ below the soil surface. Total leachate volume will be extracted once per week from each plot. Nitrate, ammonium and phosphate concentrations in leachate water will be measured once per week for one replicate from each treatment, and biweekly for all other replicates. Biweekly measurements of carbon dioxide (CO2) and nitrous oxide (N2O) gas fluxes will be taken throughout the growing season using the static chamber method.
Metrics of supporting services: Biodiversity. Annual insect biodiversity inventories will be performed at each partner UA site, in the St. Thomas Stewardship Garden plots, and in adjacent or nearby boulevards, vacant lots, or parks. At each location, site-level data will be collected including vegetative diversity and ground cover at a 100 x 100 m plot spatial scale. This will include areal coverage of impervious surface, mulch, bare ground, grass, woody vegetation, and herbaceous/weed vegetation (Quistberg et al., 2016). Twice monthly from June-September we will collect and identify insects collected in pitfall traps (3 per site), sticky cards (3 per site), and aerial net sweeps. Earthworm biomass will be quantified prior to the establishment of plots and at the end of the final project year utilizing a liquid mustard extraction protocol (Resner et al., 2015). Earthworm ash-free biomass, species diversity, and functional group will be determined.
Metrics of cultural services: Education, aesthetics and discovery. Social and cultural services (education, aesthetics and discovery) in UA and community gardens in the TCMA have been preliminarily investigated by previous work funded through the CURA Kris Nelson Community-Based Research Program Center (Grewell, 2015) under the concept of “social yield”. This work was completed in collaboration with the Urban Farm and Garden Alliance (St. Paul), one of our grower-partners. Collaborator Dr. Valentine Cadieux (Twin Cities Agricultural Land Trust (TCALT)/Hamline University) will assist in the design and implementation of surveys which assess the perceived importance of a range of cultural services provided by various land uses in the TCMA. These surveys will utilize a socio-cultural valuation approach, such as has been used in previous ecosystem service assessments (Camps-Calvet et al., 2016), and will include perceptions of cultural services such as place-making, social cohesion, aesthetic enjoyment, nature and spiritual experiences, relaxation and stress reduction, learning and education, and maintenance of cultural heritage (Camps-Calvet et al., 2016).
The preliminary results from Year 1 of our work have revealed some very interesting trends and patterns that are relevant to the academic community, our farmer collaborators, policy-makers, and municipal planners. Perhaps one of the more interesting preliminary results is our initial finding that all urban agricultural land uses we investigated in Year 1 had (on average) 5x higher hydraulic conductivity and lower bulk density in the 0-15cm depth increments of the soil as compared to unmanaged turf grass (Figure 1). This is a significant result because it points to one of the major potential co-benefits of urban agricultural land use as increased infiltration and water storage. Based on this preliminary result, we will be expanding our hydraulic conductivity sampling in Year two to include many additional sites.
(Figure 1). Saturated hydraulic conductivity differs significantly in the top 15cm of sites urban agricultural land use as compared to adjacent unmanaged turf grass.
Preliminary results perhaps of most local interest too our farmer-collaborators (and results that can be utilized by them to improve their own management practices are presented in Figures 2-7. Figure 2 shows the variability in seasonal collard yield by site (partner) and treatment within site. In particular, this figure shows that Growers Best (GB) practices (those practices chosen by our partners) may not have significantly increased yield above control or compost-only additions to soil. We will continue to monitor these same practices as we implement them in project years 2-3. Additionally, seeing their own data in comparison to others is a valuable learning experience and an opportunity for farmer-to-farmer exchange that seldom exists in urban agriculture.
(Figure 2). Seasonal yield variability between partner sites and amendments.
Our soil chemical data tended to underlie what has been seen in other urban agricultural systems. Levels of available N (Figure 3), P (Figure 4), and K (Figure 5) tended to be at high or very high levels for many of our partners. Some were surprised at how high their P values were. We are continuing to work up our seasonal water quality data to investigate the linkage between soil nutrient values and near-surface leachate.
(Figure 3). Olsen P variability between partner sites and amendments.
(Figure 4). Exchangeable K variability between partner sites and amendments.
(Figure 5). NO3 variability between partner sites and amendments.
The data for pH (Figure 6) show that these urban agricultural soils tend to be neutral to slightly alkaline in pH (a trend we have observed in most urban topsoils in the Twin Cities Metro Area). These results showed our growers that they really do not need to be concerned with adjusting their soil pH, changing some misconceptions.
(Figure 6). pH variability between partner sites and amendments.
Our organic matter data (LOI%, Figure 7), shows that with the exception of one site, these urban agricultural soils are very high in organic matter (largely due to the way they are managed and amended).
(Figure 7). Organic matter variability (as Loss on Ignition %) between partner sites and amendments.
Our educational approach is fully integrated into our project aims and intended to maximize the impact of our project across the Twin Cities urban agriculture community. Our outreach activities address each of the three levels of the Twin Cities urban agricultural community: 2 for-profit and 1 non-profit farming operations, 431 community gardens, and over 1,000 (scaled estimate from Taylor and Lovell, 2012) food producing households.
1. Annual Urban Agriculture All-Hands Meetings. Based on a pilot workshop organized in 2016 (organized by Dr. Rogers, with Dr. Small and Dr. Jelinski as presenters and Dr. Cadieux as co-facilitator), we expect academic, farmer, grower, and community participants in these meetings each year. Post workshop surveys indicated that interest and demand were high, and 80% of survey respondents agreed or strongly agreed that they had a better understanding of urban agricultural issues after the workshop. We expect that the addition of data from our proposed project will only further enrich these discussions and participant attitudes.
2. Annual presentations to Minneapolis Homegrown Food Council and St. Paul-Ramsey Food and Nutrition Council. Through the project period, we will make annual presentations on result updates to the two Food Councils organized for Minneapolis and St. Paul. These councils serve as a direct conduit to policy-makers and citizen-members and are an effective way to present research in an environment where data can effect change at those levels.
3. “Soil Kitchens” and downstream information transfer. Since 2015, Dr. Jelinski has been conducting on-site soil screening and community outreach events. To date, these events have resulted in over 700 direct contacts with community members – these events will serve as a way to communicate research results to community and household gardeners. Frogtown Farm hosts “Knowledge Share” programs which facilitate the bi-lateral transfer of knowledge from farm managers to community members, and vice-versa. The TC Urban Ag website has been revamped and is designed as an accessible resource for farmers, growers and community members which will have content built by students in conjunction with project activities.
4. Peer-reviewed publications and conference presentations. The 2 peer-reviewed publications and 2 national conference presentations will allow the Twin Cities and North Central Region to enhance our voice in the national urban agriculture conversation.
Educational & Outreach Activities
Tuesday, February 6th, 2018. Urban Agriculture “All-Hands” Meeting. Initial planning and coordination meeting with all project partners and collaborators to layout project plans, project logistics, and collaboratively make decisions on best practices for project management, data sharing, and experimental design. +6 Farmer contacts
Saturday, June 17th, 2018. Community Soil Lead Screening, Frogtown Farm Market Saturdays. +2 Farmer Contacts and +25 Community Contacts. Free on-site screening for soil lead and education/outreach regarding best practices to reduce exposure and avoid high lead soils.
Wednesday, August 8th, 2018. Picnic Tour and Exploration of the New Urban Food System Landscape, Urban Food Systems Symposium. Assisted with tour organization, demonstrated experimental design, preliminary data, and community partnerships to an audience of practitioners and researchers. +20 academy contacts, + 4 farmer contacts
Thursday, September 12th, 2018. Collaborative Evaluation of Ecosystem Services Provided by Urban Agriculture in the Twin Cities. Presentation to Homegrown Minneapolis Food Council Meeting, Minneapolis, MN 12SEP2018. +2 policy makers, + 2 municipal employees, + 3 farmers, +18 community contacts.
Wednesday, October 16th, 2018. Presentation to Ramsey County and Washington County Master Gardeners. Roseville, MN. “Lead in Urban Soils” Presenter, N.A. Jelinski. +89 Master Gardeners. Education/outreach regarding best practices to reduce exposure and avoid high lead soils.
Saturday, December 1st, 2018. Urban Farm and Garden Alliance 3rd Annual Greens Cookoff. Graduate student and technician were on event planning committee. Collard greens from research plots were utilized by community members in greens cookoff. N. Jelinski and undergraduate researchers volunteered at event. + 110 community contacts.
Urban Farm and Garden Alliance Monthly Meetings. May 2018 – Present. Last Thursday of every month – graduate student, technician, and undergraduate researchers attend meetings to provide consultation, expertise, and timely updates on project logistics and preliminary results. +2 Farmer Contacts and + 10 Community contacts.
Rondo Reconciliation Meetings. May 2018 – Present. Every second Thursday of the month – graduate student, technician, and undergraduate researchers attend meetings. Includes community members that aren’t necessarily related to farming +12 community contacts.
- Data Interpretation - Soil Nutrients and Chemical Properties
- Data Interpretation - Soil Hydraulic Conductivity and Physical Properties
- Data Interpretation - Insect Biodiversity
“I am a food systems coordinator with a large non-profit in the Twin Cities in Minnesota who work focuses on free meal programs, urban agriculture, and food shelves that serve around 13,000 people per month. One thing that I hear a lot in my position, working between community members and researchers, is that our community members constantly feel like they are part of a research project. That they are not humanized. That these privileged academics are here to tell the people in the neighborhood how they have to live, what they are doing wrong, or what they could do better. I never once felt that way about this research team. They were humble and gracious, conducting research while providing much needed fresh greens to our community cafe to serve or our food shelf to give out to the community for free. They focused on providing a benefit to the community while conducting research in a non-intrusive way. This idea was epitomized by the fact that they ate lunch with our community members every time they had a chance. Researchers and students didn’t shy away from sitting at a table with our community members experiencing homelessness that I have seen other researchers stay away from. Instead, they sat down and had conversations with these folks. Asked them what they wanted to see done in the neighborhood in regards to agriculture. The team knew these folks had as many brilliant ideas about our community as any researcher did.”