Global maize trade and food security: implications from a social network model

Abstract

In this study, we developed a social network model of the global trade of maize: one of the most important food, feed, and industrial crops worldwide, and critical to food security. We used this model to analyze patterns of maize trade among nations, and to determine where vulnerabilities in food security might arise if maize availability was decreased due to factors such as diversion to nonfood uses, climatic factors, or plant diseases. Using data on imports and exports from the U.N. Commodity Trade Statistics Database for each year from 2000 to 2009 inclusive, we summarized statistics on volumes of maize trade between pairs of nations for 217 nations. There is evidence of market segregation among clusters of nations; with three prominent clusters representing Europe, Brazil and Argentina, and the United States. The United States is by far the largest exporter of maize worldwide, whereas Japan and the Republic of Korea are the largest maize importers. In particular, the star-shaped cluster of the network that represents U.S. maize trade to other nations indicates the potential for food security risks because of the lack of trade these other nations conduct with other maize exporters. If a scenario arose in which U.S. maize could not be exported in as large quantities, maize supplies in many nations could be jeopardized. We discuss this in the context of recent maize ethanol production and its attendant impacts on food prices elsewhere worldwide.

Keywords: Food security; global trade; maize; network models.

Fig. 1

Global maize trade network, emphasizing top exporters. The node sizes are proportional to the square root of the amount of maize exported from 2000 to 2009.

Fig. 2

Probability distributions for the total import degree (k_in), export degree (k_out), and logarithms of the export and import volumes for the period of 2000–2009; for all nations importing and exporting maize.

Fig. 3

Maize export volume in million MTs from the USA to Japan, Egypt, South Korea and Taiwan; from 2000 to 2009. The blue portions of the bars represent the proportion of the total imports to Japan, Egypt, South Korea, and Taiwan coming from the United States; the green portions of the bars represent the proportion of total imports from nations other than the USA.

Fig. 4

Normalized trade volumes for top exporters (importers) to/from top importers (exporters). Top exporters are the USA, Argentina, and France (top 3); China, Brazil, Hungary (top 4–6); and Canada, Ukraine, S. Africa, and Paraguay (top 7–10). The top importers are Japan, S. Korea, Mexico (top 3); Egypt, Taiwan, Spain (top 4–7); and the USA, Netherlands, Malaysia and Iran (top 7–10).

Fig. 5

Total maize export and import volumes for top exporters and importers across different years, 2000–2009.

Fig. 6

Proportion of total global maize exports coming from the United States, 1990–2011. Data source: US Department of Agriculture Economic Research Service (USDA ERS).

Fig. 7

Network diagram of world maize trade emphasizing consumption. The threshold for the lines is 100K MT and the size of the nodes is proportional to maize consumption in that country. Source: faostat.fao.org.