The proliferation of regional trade agreements in recent years has intensified the debate on the desirability of these agreements in themselves and their coexistence with multilateral free trade under the WTO. This study contributes to this debate by analyzing trade creation and trade diversion effects of the European Union on trade flows of six major agri-food products from 1985 to 2000. An extended gravity model is estimated employing pooled data and generalized least squares methods. The results show that the developments in the EU since the mid-1980s have served to boost agri-food trade significantly among the members. Some of the growth in intra-EU trade in agri-food products came at the expense of nonmembers as the EU reduced the degree of relative openness to trade with nonmembers during this period and diverted trade from the rest of the world into the intra-EU channels.JEL classification: C13, F49, Q17

The United States is a large net exporter of corn seeds. Seed trade, including that of corn, has been expanding, but its determinants are not well understood. This paper econometrically investigates the determinants of world demand for U.S. corn seeds with a detailed analysis of trade costs impeding export flows to various markets, including costs associated with distance, tariffs, and sanitary and phytosanitary (SPS) regulations. The analysis relies on a gravity-like model based on an explicit specification of derived demand for seed by foreign corn producers, estimated based on data from 48 countries and for the years 1989 to 2004. An SPS count variable is incorporated as a shifter in the unit cost of seeds faced by foreign users. A sample selection framework is used to account for the determination of which trade flows are positive. All trade costs matter and have had a negative impact on U.S. corn seed exports. Tariffs matter most, followed by distance and SPS measures.

The recent proliferation of regional trade agreements (RTAs) has intensified the debate on their merits. This study contributes to this debate by analyzing trade creation and diversion effects of the North American Free Trade Agreement (NAFTA) on trade in six important agrifood products. An extended gravity model is estimated using pooled data and generalized least squares methods. The result shows that the share of intraregional trade is growing within NAFTA and that NAFTA has displaced trade with the rest of the world. While NAFTA has served to boost trade among its members, it reduced the degree of openness to trade with nonmembers.

The United States is a large net exporter of corn seeds. Seed trade, including that of corn, has been expanding, but its determinants are not well understood. This paper econometrically investigates the determinants of world demand for U.S. corn seeds with a detailed analysis of trade costs impeding export flows to various markets, including costs associated with distance, tariffs, and sanitary and phytosanitary (SPS) regulations. The analysis relies on a gravity-like model based on an explicit specification of derived demand for seed by foreign corn producers, estimated based on data from 48 countries and for the years 1989 to 2004. An SPS count variable is incorporated as a shifter in the unit cost of seeds faced by foreign users. A sample selection framework is used to account for the determination of which trade flows are positive. All trade costs matter and have had a negative impact on U.S. corn seed exports. Tariffs matter most, followed by distance and SPS measures.

The Raccoon River Watershed in Iowa has received considerable attention in the recent past due to frequent detections of nitrate concentrations above the federal drinking water standard. This paper econometrically investigates the determinants of variation of nitrate concentrations in the Raccoon River. The analysis relies on a generalized autoregressive conditional heteroscedastic process to model the serial dependence of volatility of the monthly nitrate concentrations in the Raccoon River. Monthly nitrate concentration data from Des Moines Water Works at Van Meter from 1992 to 2008 are used in the study. We found no statistically significant increasing trend in nitrate concentrations over the study period. There are substantial intra‐annual variations in nitrate concentrations, and we noted a very strong seasonal pattern. Variations in rainfall and temperature contribute more to the monthly variation in nitrate concentration than do the changes in nitrogen application rates.