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Article

Do direct market farms use fewer agricultural chemicals? Evidence from the US census of agriculture

  • Ethan D. Schoolman (a1)
Abstract

Are strong local food systems better for the environment than conventional food systems where relatively close proximity between points of production and consumption is not a defining characteristic? Despite growing support for efforts to strengthen local food systems, surprisingly little is known about the relationship of local food to environmental sustainability. In particular, the relationship of local food systems to the use of agricultural chemicals to manage pests, weeds and disease has not been a subject of systematic research. In this paper, I use longitudinal data from the US Census of Agriculture to explore whether growth in local food systems is associated with decreased on-farm use of agricultural chemicals. Drawing on county-level data from 1997 to 2012, I find that an increase in the strength of local food systems—whether measured as the number of farms that market products directly to consumers, or as the total value of direct market products—has been broadly associated with a decrease in spending on agricultural chemicals in the USA as a whole. But the magnitude of the relationship between direct marketing to consumers and changes in agricultural chemical use has dwindled over time, to the point where it is not clear whether contemporary local food systems are still incentivizing farmers to reduce their use of pesticides. Overall, this study lends new credence to the idea that robust local food systems can benefit the environment. But even where just one dimension of agriculture's impact on the environment is concerned, the characteristics of local food systems appear to have varied over time—a qualification that argues strongly for further research into the relationship of local food to agricultural practice.

Copyright
COPYRIGHT: © Cambridge University Press 2018 
Corresponding author
Author for correspondence: Ethan D. Schoolman, E-mail: ethan.schoolman@rutgers.edu
References
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Adams, DC and Salois, MJ (2010) Local versus organic: a turn in consumer preferences and willingness-to-pay. Renewable Agriculture and Food Systems 25(4), 331–341.
Adeel, M, Song, X, Wang, Y, Francis, D and Yang, Y (2017) Environmental impact of estrogens on human, animal and plant life: a critical review. Environment International 99(Suppl. C), 107–119.
Agricultural Marketing Resource Center (2014) Farmers’ Markets. Available at http://www.agmrc.org/markets-industries/food/farmers-markets (Accessed 1 September 2016).
Allen, P (1999) Reweaving the food security safety net: mediating entitlement and entrepreneurship. Agriculture and Human Values 16(2), 117–129.
Allison, PD (2002) Missing Data, 1st edn. Thousand Oaks, CA: Sage Publications.
Allison, PD (2009) Fixed Effects Regression Models, 1st edn. Los Angeles, CA: Sage Publications.
Anselin, L (2002) Under the hood: issues in the specification and interpretation of spatial regression models. Journal of Agricultural Economics 27, 247–267.
Avetisyan, M, Hertel, T and Sampson, G (2014) Is local food more environmentally friendly? The GHG emissions impacts of consuming imported versus domestically produced food. Environmental and Resource Economics 58(3), 415–462.
Baker, D, Hamshaw, K and Kolodinsky, J (2009) Who shops at the market? Using consumer surveys to grow farmers’ markets: findings from a regional market in northwestern vermont. Journal of Extension 47(6), 1–9.
Baumann, S, Engman, A, Huddart-Kennedy, E and Johnston, J (2017) Organic vs. Local: comparing individualist and collectivist motivations for ‘ethical’ food consumption. Canadian Food Studies/La Revue canadienne des études sur l'alimentation 4(1), 68–86.
Beam, AL, Thilmany, DD, Pritchard, RW, Garber, LP, Metre, DCV and Olea-Popelka, FJ (2016) Distance to slaughter, markets and feed sources used by small-scale food animal operations in the United States. Renewable Agriculture and Food Systems 31(1), 49–59.
Bean, M and Sharp, JS (2011) Profiling alternative food system supporters: the personal and social basis of local and organic food support. Renewable Agriculture and Food Systems 26(3), 243–254.
Bell, A and Jones, K (2015) Explaining fixed effects: random effects modeling of time-series cross-sectional and panel data. Political Science Research and Methods 3(1), 133–153.
Belotti, F, Hughes, G and Mortari, AP (2013) XSMLE—A Command to Estimate Spatial Panel Models in Stata. Available at www.stata.com/meeting/germany13/abstracts/materials/de13_mortari.pdf (Accessed 1 June 2016).
Bengtsson, J, Ahnström, J and Weibull, AC (2005) The effects of organic agriculture on biodiversity and abundance: a meta-analysis. Journal of Applied Ecology 42(2), 261–269.
Berry, W (2010) What Are People For? Essays, 2nd edn. Berkeley, CA: Counterpoint.
Biswas, S, Ali, MN, Goswami, R and Chakraborty, S (2014) Soil health sustainability and organic farming: a review. Journal of Food Agriculture and Environment 12(3–4), 237–243.
Bloom, JD and Hinrichs, CC (2017) The long reach of lean retailing: firm embeddedness and Wal-Mart's implementation of local produce sourcing in the US. Environment and Planning A 49(1), 168–185.
Bodner, TE (2008) What improves with increased missing data imputations? Structural Equation Modeling: A Multidisciplinary Journal 15(4), 651–675.
Born, B and Purcell, M (2006) Avoiding the local trap: scale and food systems in planning research. Journal of Planning Education and Research 26(2), 195–207.
Brown, JC and Purcell, M (2005) There's nothing inherent about scale: political ecology, the local trap, and the politics of development in the Brazilian Amazon. Geoforum 36(5), 607–624.
Buck, D, Getz, C and Guthman, J (1997) From farm to table: the organic vegetable commodity chain of northern California. Sociologia Ruralis 37(1), 3–20.
Cañette, I and Marchenko, Y (2016) Combining results other than coefficients in e(b) with multiply imputed data. Available at http://www.stata.com/support/faqs/statistics/combine-results-with-multiply-imputed-data/ (Accessed 12 July 2017).
Carolan, MS (2006) Social change and the adoption and adaptation of knowledge claims: whose truth do you trust in regard to sustainable agriculture? Agriculture and Human Values 23(3), 325–339.
Chagnon, M, Kreutzweiser, D, Mitchell, EAD, Morrissey, CA, Noome, DA and Sluijs, JPV (2015) Risks of large-scale use of systemic insecticides to ecosystem functioning and services. Environmental Science and Pollution Research 22(1), 119–134.
Chang, Y, Li, G, Yao, Y, Zhang, L and Yu, C (2016) Quantifying the water-energy-food nexus: current status and trends. Energies 9(2), 1–17.
Clement, MT, Ergas, C and Greiner, PT (2015) The environmental consequences of rural and urban population change: an exploratory spatial panel study of forest cover in the southern United States, 2001–2006. Rural Sociology 80(1), 108–136.
Cleveland, DA, Carruth, A and Mazaroli, DN (2015) Operationalizing local food: goals, actions, and indicators for alternative food systems. Agriculture and Human Values 32(2), 281–297.
Constance, DH, Choi, JY and Lyke-Ho-Gland, H (2008) Conventionalization, bifurcation, and quality of life: certified and noncertified organic farmers in Texas. Southern Rural Sociology 23(1), 208–234.
Cox, NJ (2011) Stata tip 96: cube roots. The Stata Journal 11(1), 149–154.
Cranfield, J, Henson, S and Blandon, J (2012) The effect of attitudinal and sociodemographic factors on the likelihood of buying locally produced food. Agribusiness 28(2), 205–221.
Crosson, P (1989) What is alternative agriculture? American Journal of Alternative Agriculture 4(1), 28–32.
Curtis, F (2003) Eco-localism and sustainability. Ecological Economics 46(1), 83–102.
DeLind, LB (2011) Are local food and the local food movement taking us where we want to go? Or are we hitching our wagons to the wrong stars? Agriculture and Human Values 28(2), 273–283.
Dormann, CF, McPherson, JM, Araújo, M, Bivand, R, Bolliger, J, Carl, G, Davies, R, Hirzel, A, Jetz, W, Kissling, W, Kühn, I, Ohlemüller, R, Peres-Neto, P, Reineking, B, Schröder, B, Schurr, F and Wilson, R (2007) Methods to account for spatial autocorrelation in the analysis of species distributional data: a review. Ecography 30(5), 609–628.
Drukker, DM, Peng, H, Prucha, IR and Raciborski, R (2013) Creating and managing spatial-weighting matrices with the spmat command. The Stata Journal 13(2), 242–286.
Duru, M, Therond, O, Martin, G, Martin-Clouaire, R, Magne, MA, Justes, E, Journet, EP, Aubertot, JN, Savary, S, Bergez, JE and Sarthou, JP (2015) How to implement biodiversity-based agriculture to enhance ecosystem services: a review. Agronomy for Sustainable Development 35(4), 1259–1281.
Economic Research Service (2000) Farm Resource Regions. Washington, DC: United States Department of Agriculture.
Edwards-Jones, G (2010) Does eating local food reduce the environmental impact of food production and enhance consumer health? The Proceedings of the Nutrition Society 69(4), 582–591.
Edwards-Jones, G, Canals, L, Hounsome, N, Truninger, M, Koerber, G, Hounsome, B, Cross, P, York, EH, Hospido, A, Plassmann, K, Harris, IM, Edwards, RT, Day, GAS, Tomos, AD, Cowell, SJ and Jones, DL (2008) Testing the assertion that ‘local food is best’: the challenges of an evidence-based approach. Trends in Food Science and Technology 19(5), 265–274.
Environmental Protection Agency (2016) Local Foods, Local Places: Summary Reports. Available at https://www.epa.gov/smartgrowth/local-foods-local-places-summary-reports (Accessed 15 July 2016).
Feenstra, GW (1997) Local food systems and sustainable communities. American Journal of Alternative Agriculture 12(1), 28–36.
Foley, JA, Ramankutty, N, Brauman, KA, Cassidy, ES, Gerber, JS, Johnston, M, Mueller, ND, O'Connell, C, Ray, DK, West, PC, Balzer, C, Bennett, EM, Carpenter, SR, Hill, J, Monfreda, C, Polasky, S, Rockström, J, Sheehan, J, Siebert, S, Tilman, D and Zaks, DPM (2011) Solutions for a cultivated planet. Nature 478(7369), 337–342.
Follett, JR (2009) Choosing a food future: differentiating among alternative food options. Journal of Agricultural and Environmental Ethics 22(1), 31–51.
Forssell, S and Lankoski, L (2014) The sustainability promise of alternative food networks: an examination through ‘alternative’ characteristics. Agriculture and Human Values 32(1), 63–75.
Galt, RE, O'Sullivan, L, Beckett, J and Hiner, CC (2012) Community supported agriculture is thriving in the central valley. California Agriculture 66(1), 8–14.
Gibbs, KE, Mackey, RL and Currie, DJ (2009) Human land use, agriculture, pesticides and losses of imperiled species. Diversity and Distributions 15(2), 242–253.
Golgher, AB and Voss, PR (2016) How to interpret the coefficients of spatial models: spillovers, direct and indirect effects. Spatial Demography 4(3), 175–205.
Good Earth Food Alliance (2016) Top 10 reasons to buy local food. Available at http://www.goodearthfoodalliance.com/top-ten-reasons-for-buying-local (Accessed 16 August 2016).
Graham, JW, Olchowski, AE and Gilreath, TD (2007) How many imputations are really needed? Some practical clarifications of multiple imputation theory. Prevention Science: The Official Journal of the Society for Prevention Research 8(3), 206–213.
Griffin, LN, Pavela, G and Arroyo, J (2015) Tourism and the treadmill of production: a cross-national analysis. Environmental Sociology 1(2), 127–138.
Guthman, J (2004) Agrarian Dreams: The Paradox of Organic Farming in California. Berkeley, CA: University of California Press.
Hallmann, CA, Sorg, M, Jongejans, E, Siepel, H, Hofland, N, Schwan, H, Stenmans, W, Müller, A, Sumser, H, Hörren, T, Goulson, D and Kroon, H (2017) More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLOS ONE 12(10), e0185809.
Halweil, B (2004) Eat Here: Reclaiming Homegrown Pleasures in a Global Supermarket. New York: W. W. Norton & Company.
Hamlin, HJ and Guillette, LJ (2011) Embryos as targets of endocrine disrupting contaminants in wildlife. Birth Defects Research Part C: Embryo Today: Reviews 93(1), 19–33.
Harel, O (2009) The estimation of R 2 and adjusted R 2 in incomplete data sets using multiple imputation. Journal of Applied Statistics 36(10), 1109–1118.
Heckman, J (2005) A history of organic farming: transitions from Sir Albert Howard's ‘war in the soil’ to USDA national organic program. Renewable Agriculture and Food Systems 21(3), 143–150.
Hemmerling, S, Hamm, U and Spiller, A (2015) Consumption behaviour regarding organic food from a marketing perspective—a literature review. Organic Agriculture 5(4), 277–313.
Hester, RE and Harrison, RM (eds) (2017) Agricultural Chemicals and the Environment: Issues and Potential Solutions, 2nd edn. Cambridge: Royal Society of Chemistry.
Hole, DG, Perkins, AJ, Wilson, JD, Alexander, IH, Grice, PV and Evans, AD (2005) Does organic farming benefit biodiversity? Biological Conservation 122(1), 113–130.
Hughner, RS, McDonagh, P, Prothero, A, Shultz, CJ and Stanton, J (2007) Who are organic food consumers? A compilation and review of why people purchase organic food. Journal of Consumer Behaviour 6(2–3), 94–110.
Hunt, A (2007) Consumer interactions and influences on farmers’ market vendors. Renewable Agriculture and Food Systems 22(1), 54–66.
Hunt, AR (2015) Civic Engagement in Food System Governance: A Comparative Perspective of American and British Local Food Movements. London, New York: Routledge.
Jarosz, L (2000) Understanding agri-food networks as social relations. Agriculture and Human Values 17(3), 279–283.
Johnson, R, Aussenberg, RA and Cowen, T (2012) The Role of Local Food Systems in U.S. Farm Policy. Washington, DC: Congressional Research Service.
Johnston, J, Biro, A and MacKendrick, N (2009) Lost in the supermarket: the corporate-organic foodscape and the struggle for food democracy. Antipode 41(3), 509–532.
Kennedy, EH, Johnston, J and Parkins, JR (2017) Small-p politics: how pleasurable, convivial and pragmatic political ideals influence engagement in eat-local initiatives. The British Journal of Sociology, 1–21. doi: 10.1111/1468-4446.12298.
Kloppenburg, J, Hendrickson, J and Stevenson, GW (1996) Coming in to the foodshed. Agriculture and Human Values 13(3), 33–42.
Köhler, HR and Triebskorn, R (2013) Wildlife ecotoxicology of pesticides: can we track effects to the population level and beyond? Science 341(6147), 759–765.
Lappé, FM and Lappé, A (2002) Hope's Edge: The Next Diet for a Small Planet. New York: Jeremy P. Tarcher/Putnam.
Lexmond, MB, Bonmatin, JM, Goulson, D and Noome, DA (2015) Worldwide integrated assessment on systemic pesticides. Environmental Science and Pollution Research 22(1), 1–4.
Lilico, A (2008) Buying local is not necessarily green. Economic Affairs 28(2), 63–64.
Low, SA, Adalja, A, Beaulieu, E, Key, N, Martinez, S, Melton, A, Perez, A, Ralston, K, Stewart, H, Suttles, S, Vogel, S and Jablonski, BBR (2015) Trends in U.S. Local and Regional Food Systems. Washington, DC: United States Department of Agriculture, Economic Research Service.
Lyson, TA (2004) Civic Agriculture: Reconnecting Farm, Food, and Community. Lebanon, NH: University Press of New England.
Lyson, TA and Guptill, A (2004) Commodity agriculture, civic agriculture and the future of U.S. Farming. Rural Sociology 69(3), 370–385.
MacRae, R, Cuddeford, V, Young, SB and Matsubuchi-Shaw, M (2013) The food system and climate change: an exploration of emerging strategies to reduce GHG emissions in Canada. Agroecology and Sustainable Food Systems 37(8), 933–963.
Maeder, P, Fliessbach, A, Dubois, D, Gunst, L, Fried, P and Niggli, U (2002) Soil fertility and biodiversity in organic farming. Science 296(5573), 1694–1697.
Mariola, MJ (2008) The local industrial complex? Questioning the link between local foods and energy use. Agriculture and Human Values 25(2), 193–196.
Martinez, S, Hand, MS, Pra, MD, Pollack, S, Ralston, K, Smith, T, Vogel, S, Clark, S, Tauer, L, Lohr, L, Low, SA and Newman, C (2010) Local Food Systems: Concepts, Impacts, and Issues. Washington, DC: United States Department of Agriculture, Economic Research Service.
McCaffrey, SJ and Kurland, NB (2015) Does ‘local’ mean ethical? The U.S. ‘buy local’ movement and CSR in SMEs. Organization and Environment 28(3), 286–306.
Meas, T, Hu, W, Batte, MT, Woods, TA and Ernst, S (2015) Substitutes or complements? Consumer preference for local and organic food attributes. American Journal of Agricultural Economics 97(4), 1044–1071.
Megicks, P, Memery, J and Angell, RJ (2012) Understanding local food shopping: unpacking the ethical dimension. Journal of Marketing Management 28(3–4), 264–289.
Mitchell, S (2009) The Corporate Co-Opt of Local. Institute for Local Self-Reliance. Available at https://ilsr.org/corporate-coopt-local/ (Accessed 16 September 2016).
Mnif, W, Hassine, AIH, Bouaziz, A, Bartegi, A, Thomas, O and Roig, B (2011) Effect of endocrine disruptor pesticides: a review. International Journal of Environmental Research and Public Health 8(6), 2265–2303.
Nabhan, GP (2002) Coming Home to Eat: The Pleasures and Politics of Local Foods. New York: Norton.
National Agricultural Statistics Service (2011) Price Program: History, Concepts, Methodology, Analysis, Estimates, and Dissemination. Washington, DC: United States Department of Agriculture.
National Agricultural Statistics Service (2014) 2012 Census of Agriculture: United States Summary and State Data. Washington, DC: United States Department of Agriculture.
O'Hara, J and Pirog, R (2013) Economic impacts of local food systems: future research priorities. Journal of Agriculture, Food Systems, and Community Development 3(4), 35–42.
O'Hara, JK (2011) Market Forces: Creating Jobs through Public Investment in Local and Regional Food Systems. Cambridge, MA: Union of Concerned Scientists.
Papaoikonomou, E and Ginieis, M (2017) Putting the farmer's face on food: governance and the producer–consumer relationship in local food systems. Agriculture and Human Values 34(1), 53–67.
Pelletier, N, Audsley, E, Brodt, S, Garnett, T, Henriksson, P, Kendall, A, Kramer, KJ, Murphy, D, Nemecek, T and Troell, M (2011) Energy intensity of agriculture and food systems. Annual Review of Environment and Resources 36, 233–246.
Peterson, GR (2013) Is eating locally a moral obligation? Journal of Agricultural and Environmental Ethics 26(2), 421–437.
Pisa, LW, Amaral-Rogers, V, Belzunces, LP, Bonmatin, JM, Downs, CA, Goulson, D, Kreutzweiser, DP, Krupke, C, Liess, M, McField, M, Morrissey, CA, Noome, DA, Settele, J, Simon-Delso, N, Stark, JD, Sluijs, JPV, Dyck, HV and Wiemers, M (2015) Effects of neonicotinoids and fipronil on non-target invertebrates. Environmental Science and Pollution Research 22(1), 68–102.
Rankin, B (2009) Local food is not always the most sustainable. Harvard Design Magazine Fall/Winter 2009 (31), 101–104.
Robertson, GP (2015) A sustainable agriculture? Daedalus 144(4), 76–89.
Rodale Institute (2014) Regenerative Organic Agriculture and Climate Change: A Down-to-Earth Solution to Global Warming. Kutztown, PA: Rodale Institute. Available at http://rodaleinstitute.org/regenerative-organic-agriculture-and-climate-change/ (Accessed 5 September 2016).
Rodman, SO, Palmer, AM, Zachary, DA, Hopkins, LC and Surkan, PJ (2014) ‘They just say organic food is healthier’: perceptions of healthy food among supermarket shoppers in southwest Baltimore. Culture, Agriculture, Food and Environment 36(2), 83–92.
Royston, P and White, I (2011) Multiple imputation by chained equations (MICE): implementation in stata. Journal of Statistical Software 45(4), 1–20.
Schneider, ML and Francis, CA (2005) Marketing locally produced foods: consumer and farmer opinions in Washington County, Nebraska. Renewable Agriculture and Food Systems 20(4), 252–260.
Schnell, SM (2013) Food miles, local eating, and community supported agriculture: putting local food in its place. Agriculture and Human Values 30(4), 615–628.
Singer, P and Mason, J (2007) The Ethics of What We Eat: Why Our Food Choices Matter. Emmaus, PA: Rodale Books.
Stehle, S and Schulz, R (2015) Agricultural insecticides threaten surface waters at the global scale. Proceedings of the National Academy of Sciences 112(18), 5750–5755.
Stock, JH and Watson, MW (2008) Heteroskedasticity-robust standard errors for fixed effects panel data regression. Econometrica 76(1), 155–174.
Story, M, Hamm, MW and Wallinga, D (2009) Research and action priorities for linking public health, food systems, and sustainable agriculture: recommendations from the Airlie conference. Journal of Hunger and Environmental Nutrition 4(3–4), 477–485.
Sumner, J, Mair, H and Nelson, E (2010) Putting the culture back into agriculture: civic engagement, community and the celebration of local food. International Journal of Agricultural Sustainability 8(1/2), 54–61.
Sustainable Table (2016) Local & Regional Food Systems. Available at http://www.sustainabletable.org/254/local-regional-food-systems (Accessed 27 August 2016).
Thilmany, D, Bond, CA and Bond, JK (2008) Going local: exploring consumer behavior and motivations for direct food purchases. American Journal of Agricultural Economics 90(5), 1303–1309.
UCLA: Statistical Consulting Group (2015) Stata Library: Analyzing Correlated (Clustered) Data. Available at www.ats.ucla.edu/stat/stata/library/cpsu.htm (Accessed 10 July 2015).
U.S. Bureau of Labor Statistics (2017) Producer Price Index by Commodity for Machinery and Equipment: Agricultural Machinery and Equipment. St. Louis, MO: Federal Reserve Bank of St. Louis. Available at https://fred.stlouisfed.org/series/WPU111 (Accessed 8 October 2017).
Vilsack, T (2016) New Markets, New Opportunities: Strengthening Local Food Systems and Organic Agriculture. Available at https://medium.com/usda-results/new-markets-new-opportunities-strengthening-local-food-systems-and-organic-agriculture-17b529c5ea90#.lwdvc0eft (Accessed 14 August 2016).
Von Hippel, PT (2009) How to impute interactions, squares, and other transformed variables. Sociological Methodology 39(1), 265–291.
Watts, M and Williamson, S (2015) Replacing Chemicals with Biology: Phasing Out Highly Hazardous Pesticides with Agroecology. Pesticide Action Network Asia and the Pacific. Available at http://panna.org/sites/default/files/Phasing-Out-HHPs-with-Agroecology.pdf (Accessed 5 October 2017).
Weber, CL and Matthews, HS (2008) Food-miles and the relative climate impacts of food choices in the United States. Environmental Science and Technology 42(10), 3508–3513.
Wezel, A, Casagrande, M, Celette, F, Vian, JF, Ferrer, A and Peigné, J (2014) Agroecological practices for sustainable agriculture: a review. Agronomy for Sustainable Development 34(1), 1–20.
White, IR, Royston, P and Wood, A (2011) Multiple imputation using chained equations: issues and guidance for practice. Statistics in Medicine 30, 377–399.
Wolf, MM, Spittler, A and Ahern, J (2005) A profile of farmers’ market consumers and the perceived advantages of produce sold at farmers’ markets. Journal of Food Distribution Research 36(1), 91–98.
York, R and Rosa, EA (2012) Choking on modernity: a human ecology of air pollution. Social Problems 59(2), 282–300.
Youngberg, G and DeMuth, SP (2013) Organic agriculture in the United States: a 30-year retrospective. Renewable Agriculture and Food Systems 28(4), 294–328.
Zulauf, C and Rettig, N (2015) Have U.S. farm input prices followed U.S. crop prices? Farmdoc Daily 5, 171. Available at http://farmdocdaily.illinois.edu/2015/09/have-us-farm-input-prices-followed-us-crop-prices.html (Accessed 21 June 2017).
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