Breaking with natural constraints: provincial grain yields in Spain 1750-2009

"This paper estimates the yields for five grains in 33 provinces of Spain in the mid eighteenth century. The results show that yields were higher in the north of the country, and that the most fertile provinces of Spain were not far behind the most advanced agricultural regions of the world. Average wheat yields in Spain remained stagnant between 1750 and the late nineteenth century when they doubled just to remain stagnant again until the modernization of the primary sector in the 1960s. Our results show that in the very long run yields between provinces tended to convergence, and that it was from the 1960s when the traditional differences in provincial yields began to disappear. The use of artificial fertilizers or new wheat strains were key improvements that helped low yield provinces to break with severe natural constrains such as the lack of rainfall or low quality soils."