The Science of Local Food

Overview

The local food movement has flourished in recent years, with direct-to-consumer marketing accounting for over $1.2 billion in sales in the U.S. annually. Farmers markets and community-supported agriculture are on the rise, with consumers turning to local food systems in hopes of finding healthier, tastier, environmentally-conscious, and energy-efficient alternatives to industrial foods. Although the movement is growing rapidly, research into whether local food is indeed more nutritious and sustainable is still in its infancy. The Science of Local Food—presented at the South Street Seaport Museum on June 26, 2012 by Science & the City, the Sackler Institute for Nutrition Science, and New Amsterdam Market—explored the true value of local food and discussed its environmental and cultural impacts. This was the last event in the Locavore's Dilemma series.

Robert LaValva, founder and president of New Amsterdam Market, set the scene by emphasizing the important role that local food markets have historically played in New York City, particularly in the South Street Seaport neighborhood. Despite the recent growth in the local food movement, markets such as the Fulton Fish Market have been operating in the South Street Seaport region for centuries, with some dating back to 1642 when ferries began to bring Long Island produce to Manhattan. Thus, local food is strongly rooted in NYC, a region surrounded by high quality farmland.

Any discussion of local food must first identify which foods qualify as local. This can be challenging because there is no single definition to guide consumers. Food miles, defined as the distance that food travels from producer to consumer, is often used as a guideline. 'Local' is sometimes considered 100 to 200 miles or the distance one can drive in a day; however, the panelists agreed that the concept of local has expanded recently to include a more regionally-defined area. At the New Amsterdam Market, LaValva defines local as within 500 miles of NYC, using a regional scale that approximately encompasses the northeast United States—he noted that this definition is fluid and changes as the market develops and suppliers change. Brian Halweil, editor of Edible East End, a senior fellow at the Worldwatch Institute, and co-director of the Nourishing the Planet project, explained the benefits of an inclusive regional definition. He pointed out that there is, for example, a lack of grain-production capacity in the NYC area but high availability in nearby regions like Pennsylvania and the Finger Lakes. NYC is able to access a more diverse food supply and to guarantee a self-reliant food system, while still focusing on sourcing locally, by defining local as the closest-available product rather than limiting its supply by a specific distance. One limitation of this approach is that it does not necessarily extend to all food products; coffee or chocolate, for example, can only be produced in other countries, so even the closest producers of these foods would not be considered local to NYC. For Peter Hoffman, chef/owner of two farm-to-table restaurants, a good approach is to source locally if possible and to buy food that is in season. However, Hoffman does purchase globally-sourced ingredients, such as sugar, olive oil, and chocolate, taking the agricultural management practices of these producers into account.

Jennifer G. Phillips, assistant professor at the Bard Center for Environmental Policy, researches sustainable farming systems and climate risk-management strategies for eastern New York State. Phillips discussed food miles, a concept that was developed to reduce the impact food production has on greenhouse gas emissions by limiting food transportation. She argued that food miles are not the most important contributor to environmental impacts. Studies show that transport accounts for only 11% to 12% of emissions from food production; the bulk of emissions result, instead, from nitrogen fertilizer production and application. Furthermore, in addition to greenhouse gas emissions, there are a number of other negative impacts that food systems can have on the environment—such as soil erosion, soil organic matter depletion, and reduced water quality—which are not necessarily mitigated by sourcing locally. Therefore, whether a product is 'local,' or has traveled a short distance, is not in itself sufficient to determine the environmental impact of its production; the values and management practices governing production can be much stronger indicators.

The panelists described a local food system as one that brings producers and consumers together. Hoffman described multiple benefits to purchasing food from the person who grew it. A local food system can help create a sense of community, support local producers and businesses, and help prevent urban sprawl by keeping farmland near urban centers. Local food markets also offer the public the opportunity to ask questions about farm management practices and to purchase from farmers who share their values, thus creating a more educated consumer and instilling a sense of responsibility in the producer. Phillips advised consumers to ask specific, informed questions; for example, rather than ask whether cattle are grass-fed, ask how often they are rotated to a new field. The panelists also emphasized that not all local food is 'grown equal.' The mere fact that a product is labeled as local or can be found at a green market does not guarantee that it comes from a small and diverse farm or that it is organic, ethical, or sustainable. The panelists agreed that interacting with producers is one of the best ways to identify good farming practices.

After discussing the parameters of local food, the panel shifted to the science of local food. According to Halweil, research into whether local, sustainably-grown food is more nutritious than industrial food is "murky," but some broad conclusions indicate that it has advantages. First, nutrients may degrade if food is transported for long periods of time or is not stored properly; this gives local food an advantage, assuming it gets to the consumer quickly. Second, heirloom varieties of certain plants such as wheat, corn, and cauliflower have higher levels of micronutrients than newer crops selected for high yields; these older varieties are more likely to be found on smaller, more diverse farms. Lastly, agricultural management practices, such as irrigation and fertilization, can affect the nutritional value of food; industrial farms tend to rely heavily on practices that produce more watery plants with fewer nutrients.

LaValva posed a question to the panel: What are the most important aspects of food production? Hoffman expressed the importance of taste as a consideration for food production, stating that, in his experience, produce grown at local, organic farms typically tastes better than industrially-grown food. Halweil emphasized that one of the best ways to limit the environmental impacts of food production and delivery is to eat seasonally as well as locally. This not only reduces food transportation but also limits energy use for food storage. Phillips proposed that two important components of sustainable food production are diversity and scale. Small-scale farms are typically associated with higher crop diversity and are often able to employ a larger array of sustainable management-practices. Crop diversity promotes nutrient cycling and supports a wider range of beneficial insects and soil microbes than does a monoculture system. According to Phillips, as field size is scaled-up, farms begin to lose certain advantages; for example, beneficial insects living in hedgerows are unlikely to reach the middle of a large field. Regions lacking crop diversity, such as the vast cornfields of the Mississippi Basin, exhibit more erosion and topsoil runoff, and water bodies in these areas have higher levels of pesticides and nitrogen fertilizer. Industrial monoculture farms dominate regions like the Midwest, which, as a result, no longer grow their own food; thus, according to Hoffman, these farms are the antithesis of the local food movement. Diversity within both a farm and a region is not only ecologically sound but also supports regional food security and self-reliance.

Despite the advantages of local and organic farming, there are some limitations to the applicability of these methods in global food systems. Because local farms operate almost by definition on a smaller scale than their industrialized counterparts they do not have the capacity to adequately supply population-dense, growing metropolitan areas like those in the northeast U.S., where rolling topography limits the size of farms relative to the prairies of the Midwest. Although micro-scale farms may be better able to reduce the environmental impacts of food production, in reality it is not possible for these farms to feed the 7 million people living in NYC. Interacting directly with producers each time we buy food is also perhaps unrealistic. A major challenge for science in the coming years is to identify how to grow food sustainably on a large scale. According to Phillips, this will require advances in soil and agricultural science to identify which crops should be grown as we try to move away from highly fertilized and highly irrigated farming practices. Furthermore, it will require new social organization and food distribution systems that implement environmentally- and economically-conscious methods to bring sustainably-grown food to large suppliers.

A tension exists between creating policies for improving health and allocating resources for food production. As the panel concluded, Halweil left the audience with something to think about: Should public health initiatives devote energy and resources to ensuring that people eat well, by investing in local and organic food, or should efforts be focused on encouraging people simply to eat more vegetables, regardless of how these are produced? In other words, should government focus on making local food more accessible? Is local food worth investing in?

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Presentations available from:
Brian Halweil (Edible East End)
Peter Hoffman (Back Forty & Back Forty West)
Robert LaValva (New Amsterdam Market)
Jennifer G. Phillips (Bard Center for Environmental Policy)

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