Developing Soil Fertility Systems for Urban Agriculture in the Upper Midwest

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2012: $7,239.00
Projected End Date: 12/31/2013
Region: North Central
State: Minnesota
Project Coordinator:
Alexander Liebman
Stone's Throw Urban Farm

Annual Reports


  • Vegetables: broccoli, greens (leafy), peppers, tomatoes


  • Crop Production: cover crops, intercropping, nutrient cycling, organic fertilizers
  • Education and Training: demonstration, networking, on-farm/ranch research
  • Farm Business Management: budgets/cost and returns, agricultural finance
  • Production Systems: agroecosystems
  • Soil Management: green manures, organic matter, soil analysis, soil microbiology, soil quality/health
  • Sustainable Communities: local and regional food systems, urban agriculture


    We tested the impact of different cover crops and the addition of compost on small-scale urban production systems. I specifically want to learn how cover crops can be best integrated into intensive vegetable production systems and how their impacts can be measured to ensure best practices. Rye/vetch, oats/peas, and clovers, with or without the addition of compost, were established following cash crops in the fall of 2012. I measured metrics of soil health such as organic matter, soil bulk density, and pH, in summer 2012 and spring 2013 to determine the before/after influence of cover crops. I also measured cover crop biomass to determine the extent to which different cover cropping methods contributed to soil organic matter.

    Overall, soil organic matter and nitrate concentration increased across treatments with no clear association with cover cropping method. The pH decreased across all treatments, also with no connection to cover cropping or compost application. Bulk density levels varied largely yet overall increased across all treatments, with higher rates of increase where compost was applied with or without cover cropping.


    Stone's Throw Urban Farm is a 3-acre vegetable operation located on previously vacant lots throughout the cities of Saint Paul and Minneapolis in Minnesota. The farm produces food for a 100-person Community Supported Agriculture (CSA) program, the Mill City Farmer’s Market, and several restaurant and wholesale accounts. The farm is committed to growing high-quality produce and a sustainable livelihood while improving the ecological health of its land and engaging the surrounding community in on-farm education and equitable food access. Growing food in an urban setting has great potential for increasing local foods availability, decreasing transportation costs, and educating an urban populace on the pressing agricultural issues of our time. However, production systems are under-researched. We are intent on developing scientific, agro-ecological approaches to improving the capacity of urban agriculture.

    We developed this experiment to learn how the integration of different cover cropping strategies could help our urban farm to improve soil health while not conflicting with production demands. As an urban farm, implementing agricultural production on previously marginal land, soil building and conservation strategies are imperative to the long-term success of our operation. However, due to our limited acreage and insecure land tenure (two major issues facing the development of urban agriculture), long-term cover cropping strategies are impractical. In addition, the short growing season of northern climates, such as Minnesota, creates a small window for the growth of both cover and cash crops. Therefore, we are experimenting with ways in which we can build soil structure and organic matter without sacrificing cash crop space.

    This experiment was an initial step at determining 1) how cover-cropping methods fit into our production scheme and 2) how different cover cropping methods differed in their ability to improve soil quality. We experimented with the establishment of rye/vetch, oats/peas, and clover in the fall, after the harvest of a main crop or intercropped with an existing tomato crop.

    Project objectives:

    In 2012, we had several main objectives. These were to:
    - Establish cover cropping practice within existing farm system
    - Measure soil bulk density for 2013 comparison
    - Measure cover crop biomass for 2013 comparison
    - Measure soil nitrogen, organic matter and pH for 2013 comparison
    - Photo journal to track cover-crop growth
    - Track costs/labor
    - Host several outreach events to surrounding agricultural and community garden community

    As summarized in the 2012 midterm report, these tasks were completed. During the 2013 season, our objectives were:
    - Sample all plots for follow-up soil tests, bulk density measurements, and biomass measurement for comparison to 2012 collected data
    - Data analysis: compile data and synthesize
    - Continue outreach
    - Qualitative descriptions of residue decomposition and success of succeeding crops These activities are summarized in the Accomplishments/Milestones section below.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.