In addition to his work studying recycled nutrients in the soil of the community garden, professor Chip Small studies the same phenomenon in hydroponics, where the waste from fish is used to feed aquatic plants. (Photo by Mike Ekern ’02)
It’s easy to assume everything is ready to continue smoothly in the growing field of urban agriculture: Urban home and community gardens pop up more and more, and the evidence of sustainability and social benefits continues to grow. More of a good thing is a good thing, right?
Well, hold that thought. As is often the case with the complexities of modern life, there’s a bit more to the picture. Freshly armed with a $500,000 grant over five years from the National Science Foundation, St. Thomas biology faculty Chip Small and Adam Kay, and their students, are primed to contribute some much-needed science: They will be studying what effects recycled nutrients have in the soils of community gardens, which could greatly help shape the future of how urban ecosystems handle food.
“The main focal point of the grant is on the use of nutrients and how to recycle them efficiently. That’s such a general issue for an expanding population,” Kay said. “We know the stats of how 40-some percent of food is wasted in the agriculture system, so thinking about how the human civilization collectively can operate more efficiently, we’re going to need that moving forward.”
Small, who secured the funding as an early career grant, has been studying nutrient recycling in different ecosystems since his Ph.D. research and recently has shifted his lens to urban ecosystems.
“I’ve been asking questions about how efficiently we can recycle nutrients from food waste into new food through composting, coupled with urban agriculture,” Small said. “Something like nearly half the food imported into cities ends up as waste, and we compost maybe 5 percent of that waste. Theoretically that could be scaled up and provide lots of nutrients for urban agriculture.”
Of course, scaling anything up means increasing the amount of everything in play and, when it comes to growing food, that means increasing the amount of phosphorus.
“There’s sort of a nutrient mismatch between compost and what crops need. Compost, food waste, manure tend to have a lot of phosphorus relative to nitrogen,” Small said. “What we’re seeing is a lot of urban gardens that … are leeching out phosphorus. We have laws in Minnesota that you can’t just put phosphorus fertilizer on your yard because we’re concerned about water pollution and phosphorus going into lakes. But, you can put as much compost as you want in your garden and you might have the same effect. Nobody has really looked at that. That’s the research question.”