The world needs an agricultural makeover. Currently, agricultural practices take up 40 percent of land area, are responsible for 70 percent of global water withdrawals, and emit 30 percent of all greenhouse gases in our atmosphere (Foley 2010). The amount of land used for agriculture is 60 times higher than land use for all other human activity. At the same time, about one billion people are chronically malnourished (Conway 2010). Moreover, global food demand is predicted to increase by 50% by 2050 as populations grow, economies develop, and diets shift to include more meat and more calories (Tilman et al. 2011). To address these issues simultaneously, we need to develop ways to produce more food with less environmental impact on land that has already been modified by human activity.
One part of the solution can be the development of agriculture in urban environments (Ladner 2011). Converting urban lands from lawns (or even parking lots) to agricultural fields probably doesn’t impact the environment as much as forest or prairie conversion does. Urban agriculture has a lot of other benefits too: it reduces food transportation costs, it can connect people to the process of food production, and it can help build community (Ferris et al. 2012). Urban agriculture projects can also help raise awareness about the challenges facing global agriculture.
Part of the mission of the Stewardship Science team at the University of St. Thomas is to conduct visible research on how to best use urban land for food production in a sustainable way. Our research at the Stewardship Garden on the UST St. Paul campus examines the tradeoff between maximizing vegetable production yield and minimizing environmental impacts. This year, we are conducting a competition to better understand this tradeoff. We’ve asked participants from across the university and the urban agriculture community to specify the growing conditions on our plots. Participants were asked to make simple choices about fertilizer type, fertilizer amount, water management technique, and crop type. “Fertilizer type” choices were either a synthetic 24N-8P-16K blend, or a barley compost produced by Giving Tree Gardens that consists of beer-mash waste from five local breweries, coffee-roast waste from Peace Coffee, organic-landscaping waste, and wood chips. “Fertilizer amount” choices are either “low” (64g N/m2/yr for synthetic, 7.5 cm depth for compost) or “high” (128 gN/m2/yr for synthetic, 15 cm depth for compost). “Water management technique” is either [mulch (3cm wood chips) + no water] or [no mulch + water added to offset evapotransporation]. “Crop type” is either conventional or heirloom varieties of common garden vegetables. We are managing the plots according to the specifications of participants. The Garden has two replicates of each possible combination of the choices for a total of 32 plots. Every plot has lettuce, full tomatoes, cherry tomatoes, eggplant, green beans, peppers, potatoes, and squash. We weigh all of the produce from the plots, and quantify an environmental impact by measuring nutrient run-off from each plot. The winning strategy will be the one that maximizes the yield-to-environmental impact ratio; in other words, vegetable production per amount of nutrient runoff.
We thought we would share some mid-summer results. Keep in mind that these results are preliminary. For example, tomato and potato production is only just starting to take off. We also haven’t calculated vegetable monetary value, and we haven’t yet analyzed our run-off samples. That said, the preliminary results are interesting.
So far, there is significantly higher production from compost vs. synthetic fertilizer plots (F1,27=42.5772, p<0.001); compost plots have ~70% more yield than those getting synthetic fertilizer. Higher amounts of fertilizer produced significantly higher produce yields (F1,27=11.6063, p=0.0021), although the doubling of fertilizer use has only produced about 50% more yield. Water management technique has so far not affected crop yield (F1,27=0.5310, p=0.4724), suggesting that mulching can completely offset irrigation needs (at least during a wet early summer like we had this year). Finally, we’ve found that conventional crops yield more than heirloom varieties (F1,27=4.6698, p=0.039), although this result is based largely on yields from our squash plants. Overall, the highest producing plots are those with high levels of organic compost and conventional crops. The current leading plot has over 25,400 grams of vegetable production.
St. Thomas has been using the garden for three years to inform students, faculty, staff, and neighbors about what St. Thomas is doing to work to find solutions to our agricultural crisis and meet local food demands. The produce grown in the Stewardship Garden goes to Neighbors Inc., a food shelf in South St. Paul (so far we’ve donated ~2,000 lbs this year!). Other produce grown by our team goes to St. Thomas dining services and the new UST Farmers Market, providing fresh, local food to students and faculty/staff. Over the years, our team has worked to build a network of like-minded partners around the Twin Cities area to help inform the public about a sustainable, urban food system.
If you are interested in visiting the Stewardship Garden, we have an exciting event coming up! September 13th is Community Garden Day! From 2pm to 4pm we will be hosting a carnival with games, refreshments, and tours of the garden. Also, visit the UST Farmer’s Market every Friday 11AM-2PM until October in the Monahan Plaza.
Leann Luecke and Adam Kay also contributed to this post