Authors: Isabel Calha, Senior Researcher (INIAV), Margarida Teixera Santos, Substitute Lab Manager (INIAV)
Today, sweet potato is attracting renewed attention in Europe as a crop with potential to support more diversified and resilient farming systems. Within ROTATES, researchers are exploring varieties, agroecological practices and new value chains to better understand how this crop can contribute to the future of European agriculture. Yet sweet potato is far from being a new crop in Portugal. Historical records show that it has been cultivated in the country since the 16th century, with an important presence in regions such as the Algarve, Madeira and the Azores. Looking back at how the crop was cultivated decades ago offers a fascinating perspective on the diversity, knowledge and farming practices that already existed in Portugal.
A particularly interesting window into this history is provided by two studies produced at the Instituto Superior de Agronomia in Lisbon in the 1940s. At the time, the institute was already an established centre for higher agricultural education and research, having become part of the newly created Universidade Técnica de Lisboa in 1930. The two works, by Bento dos Santos Nascimento in 1944 and Rui Nolasco da Silva in 1946, document different aspects of sweet potato production in Portugal and provide a detailed snapshot of the crop at the time.
Nascimento’s A cultura da batata doce na província do Algarve focused specifically on production in southern Portugal, covering the different stages of cultivation as well as rotation, curing, conservation, culinary uses and animal feed. The work was presented as a final report for the agronomy engineering course and included extensive photographic material. Nolasco da Silva’s 1946 study, meanwhile, focused on the cultivated varieties of sweet potato in Portugal, documenting fifteen varieties from the Algarve, Setúbal, Madeira, Porto Santo and São Miguel in the Azores.
The study recorded differences in skin and flesh colour and included detailed drawings of the leaves of several varieties. The names themselves give a sense of the diversity that characterised Portuguese sweet potato production at the time. Varieties such as Raiz de Cana, Lírio, Santinha, Machiqueira, Barbiça and Roxa de São Miguel were associated with different regions and displayed distinct characteristics. Some had white flesh, others yellow or purple, while the colour and appearance of their storage roots varied considerably. The records therefore provide not only a historical account of production but also a glimpse into a rich crop diversity that was already being studied and documented more than eighty years ago.
The photographs included in Nascimento’s work offer another perspective. They show aspects of cultivation and local transport in the Algarve, providing a rare visual record of how sweet potato was produced and moved through rural landscapes in the 1940s. Together with the descriptions of nurseries, cultivation methods, rotations, storage and uses, they show that sweet potato was not simply a crop grown in isolation. It was part of broader farming systems and local food practices, with uses extending from human consumption to animal feed.
For ROTATES, these historical records provide an interesting starting point for looking at the crop today. The project is working with partners in Portugal and other European regions to explore how sweet potato and other Minor Root and Tuber crops can contribute to more resilient and diversified farming and food systems. The research carried out in the 1940s reminds us that this work does not begin from scratch. Portugal already has a long history of cultivating, using and characterising sweet potato, including a diversity of varieties and practices that can help inform today’s research.
Bringing this historical perspective together with current research also reflects one of the principles at the heart of ROTATES: combining different forms of knowledge to develop better solutions for the future. The studies produced by Nascimento and Nolasco da Silva offer a window into Portuguese agriculture eighty years ago. Today, researchers, farmers and other stakeholders are adding new knowledge to this history, exploring how the potential of sweet potato can be developed for the farming and food systems of tomorrow.
