Agroecological practices such as cover cropping may address challenges that urban gardeners face (e.g, building soil quality with limited access to organic amendments), thus enhancing the productivity and sustainability of urban agriculture. This presentation will share our experiences in a collaborative inquiry (CI) project with Brooklyn gardeners on cover cropping and inquiry-based gardening education.
Agroecological research questions include: How do species composition and management of over-wintering cover crops affect soil cover, biomass, nitrogen fixation, and weed suppression in urban vegetable gardens? and, How do soil properties, light availability, and intercrops influence cover crop performance? In Fall 2011, we under-seeded four cover crop combinations (crimson clover, wheat/clover, hairy vetch, and wheat/vetch) in 100 garden plots, and monitored fall cover crop performance in terms of soil cover, nodulation, and weed suppression.
We also explored the value of CI for research and education. Through case studies of two CI groups, we asked: How can CI be organized and facilitated in an urban community gardening context to achieve educational, social, and environmental benefits? Data included facilitator field notes, critical incident questionnaires, narrative interviews, group evaluation sessions, and workshop products (e.g., gardeners’ evaluations of cover crops).
In contrast to trends found in rural areas, legume monocultures exhibited higher percent cover three weeks after planting than legume-wheat mixtures because plots with wheat seed attracted birds, resulting in seed predation and poor cover crop establishment. In urban environments, it may be necessary to protect cover crop seeds with row cover or mulch. After six weeks, all cover crops provided excellent average soil cover (84 – 92%) and weed suppression (88 – 97% reductions in weeds compared to control plots). Crimson clover provided better soil cover and weed suppression, while more vetch plants developed pink inner nodules, suggesting that vetch may begin nitrogen fixation more quickly.
Initial reflections on the CI process show that it may strengthen and contextualize scientific inquiry with local knowledge; provide learning opportunities that build ecological understanding and adaptive management skills; and foster improvements in stewardship practices. Several aspects of CI emerged as important to realizing these benefits, including: engaging citizens in defining goals and research questions; facilitating repeated cycles of reflection and action, informed by monitoring agroecological outcomes of new practices; and a collaborative process in which gardeners meet to reflect on their experiences. Difficulties included fostering sustained engagement, coordinating among participants with differing schedules, and designing accessible record-keeping forms and processes.