Agricultural Expansion, Soil Degradation, and Fertilization in Portugal, 1873–1960: From History to Soil and Back Again

Abstract

AbstractThis research explains what happened to agricultural soil fertility during the “Campanha do Trigo” (Wheat Campaign) in Portugal, which began in 1929. It is commonly understood that the excessive expansion of wheat crops during the fascist “Estado Novo” (New State) regime led to the degradation of soils in the southern half of Portugal. This relationship, however, has never been questioned before. This article extends the narrative back into the last half of the nineteenth century in search of the origin of processes that gradually intensified throughout the country. In short, expansion of the cultivated area in association with the inadequate intensification of crop rotations over about 80 years, from the 1870s onward, including in non-wheat areas, strongly accentuated soil erosion and made organic fertilization progressively less effective. These transformations were only partially offset by chemical fertilization. Nitrogen and phosphorus were the key factors in this historical process. Focusing on the cultivation system and soil dynamics allows the successive integration of various kinds of historical evidence and sources. From an environmental question—why did agricultural soil degrade?—this article explores soil degradation over time and space, and assesses its social and biophysical impacts. At the same time, it addresses the history of agriculture in Portugal and its disciplinary foundations.