摘要：Much of the world's agricultural productivity growth over the past fifty years has been attributed to the international spillover of benefits from research and develop- ment (Alston, 2002). Because the impact of these spillovers often varies with distance, geography, and climate, attention has increasingly focused on measuring their spa- tial dimensions Evenson (1989). In this paper, spatial spillovers are examined in the context of country borders. Using high-resolution worldwide grid cell data covering yields for 11 major crops, we test whether spatial dependencies in agricultural yields fall in the presence of country borders, controlling for geography and climate as well as country-specific effects. Two different complementary analyses show that country borders significantly and sizeably diminish the transmission of spatial spillovers be- tween locations. The results thus point to a clear \border effect" on an important determinant of agricultural productivity.
