Urban community gardeners make important contributions to healthy food access and environmental stewardship. I conducted gardener interviews and ecological sampling to describe agroecological and social characteristics of 61 food-producing gardens in New York City. Gardeners devoted the greatest proportion of garden area to food production and supplied substantial shares of their households’ produce needs. Challenges for sustainable crop production included: poor soil quality in raised beds due to sandy textures and low water-holding capacities, excessive soil nutrient contents, insect pest damage, and weed pressure.
To identify promising cover crops for enhancing ecosystem services, I conducted field experiments in 17 Brooklyn, NY gardens over two field seasons. Compared to winter-kill cover crops, over-wintering cover crops had greater biomass, weed suppression, legume % N from fixation, and N fixed. Rye and rye/legume bicultures were most productive (average biomasses > 10,000 kg/ha). On average, hairy vetch and crimson clover monocultures and rye/vetch mixtures fixed 190 kg N/ha or more, enough to supply vegetable crop needs. Rye/vetch mixtures showed complementary and facilitative interactions, while rye/crimson clover and oat/pea mixtures had low legume biomass and total N fixed. Surprisingly, compared to vetch monocultures, rye/vetch mixtures had greater legume soil N uptake (possibly due to priming of SOM decomposition by rye root exudates) and lower % N from fixation. Finally, I conducted a case study of the participatory action research (PAR) project described above to address the question: How can PAR be designed to achieve positive outcomes for science, education, and communities? Collaborative research design and interpretation tapped gardeners’ local knowledge to improve our practices. Engaging gardeners in cover crop monitoring strengthened their ecological knowledge and adaptive management skills. Facilitating opportunities for participants to share their knowledge (e.g., field days) supported leadership development. Sustained, in-person support enabled gardeners to implement cover cropping practices with agricultural and environmental benefits. Key challenges included: addressing community-defined goals within the constraints of a dissertation project and providing sufficient one-on-one guidance with limited funding for community-based partners. Despite its challenges, PAR in urban gardening contexts may develop knowledge and skills that support improved stewardship practices and community capacities.