The world’s population grows yearly, so increasing food production is necessary, to meet consumer demands. This production must be clean; thus, sustainable agriculture seems to represent a solution. However, social, economic, and environmental barriers impede the adoption of this practice. Therefore, this research identified these barriers, according to the sustainability triple-bottom line through a literature review, and analyzed which barriers are more influential and vulnerable to influences, using the Fuzzy DEMATEL method, as well as by considering the opinions of 30 mixed crop producers. As a result, eleven barriers were identified; and “technical knowledge and qualified workforce” was the most influential on not adopting sustainable agriculture. A multi-criteria model was provided and could be replicated in further research. Thus, sustainable practices are provided, to minimize the barriers’ negative impacts and assist producers; highlighting investment and policies for training farmers to have the technical knowledge to practice sustainable agriculture. Theoretical implications were reviewed, such as an analysis of the barriers found in the literature and the lack of studies reporting on the difficulty of producers in adopting sustainable agriculture, as well as the practical implications of providing assistance and transferring knowledge, to eliminate these barriers, so that sustainable practices can be efficiently implemented.

The circular bioeconomy (CBE) is an increasingly popular method used to add value to bio-based products. However, these products entail impacts on sustainability that can be assessed by life cycle thinking (LCT). Therefore, this manuscript aims to describe the current development of using LCT for a CBE and to identify challenges and future perspectives with regard to this topic. A systematic literature review was conducted using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA), analyzing a final portfolio of 57 documents. The results indicated that the use of LCT for a CBE is very recent and has been increasing over the years, is concentrated in Europe, and mainly assesses the conversion of biowastes in biofuels through biorefinery processes, considering mostly environmental concerns, by applying life cycle assessment; thus neglecting economic and social issues. The use of system boundaries, software, databases, and impact assessment methods was reviewed. Five challenges were revealed (the expansion of system boundaries, the consideration of more endpoints, the development and use of regional databases, the development of policies to encourage CBE, and the addition of economic and social issues. Future perspectives will be aimed at considering microalgae, wastewater, and animal biomass in CBE processes, developing more value-added bioproducts and biofuels, and adding cost assessment and more circularity to CBE processes.