The Role of Lupins and Buckwheat in Sustainable Agriculture, Nutrition, and the Circular Economy

Buckwheat (Fagopyrum esculentum) and lupins (Lupinus spp.) are traditional crops gaining renewed attention due to their nutritional value, ecological adaptability, and potential role in sustainable agriculture. Both are rich in high-quality proteins, essential amino acids, and bioactive compounds that support human health and meet the growing demand for plant-based foods. In addition to their nutritional importance, these crops can be cultivated on marginal soils with low fertilizer requirements, making them valuable components of climate-resilient cropping systems. Beyond nutrition, both crops generate processing by-products such as husks and ashes, which are increasingly important in the context of fertilizers, bioenergy, and biomaterials, illustrating the dual value of these crops in sustainable and circular systems. This review summarizes data on cultivation, yield, and chemical composition and highlights the multiple pathways for by-product valorisation across food, energy, and environmental applications, contributing to the development of bio-based and circular economy strategies.