**4. Conclusions**

To meet the ever-increasing interest towards agricultural sustainability, many methodologies and tools emerge, introducing integrated and holistic assessment approaches. However, there is still no consensus on the standardization of agricultural sustainability assessment as part of a unified concept of sustainable development. Newly introduced frameworks propose mostly case-specific tools that focus on resource use and their impact on the sustainability of farming practices. Combinational use of methodologies is observed in many cases; thus, a clear distinction of methodologies is not always possible. Contributing towards the indexing of the available methodologies, the present paper presented a methodological framework for the systematic literature review of agricultural sustainability studies. The framework synthesizes all the available literature review criteria and introduces a two-level analysis facilitating systematization, data mining, and methodology extraction.

The framework was implemented for the systematic literature review of crop agricultural sustainability assessment studies at farm-level for the last decade. The investigation of the methodologies used is of particular importance since there are no standards or norms for the sustainability assessment of farming practices. The chronological analysis revealed that the scientific community's interest in agricultural sustainability has been increasing during the last three (3) years, indicating a tendency to gradually progress from the theory of economic growth to the more comprehensive and inclusive concept of sustainable development. Nevertheless, the critical evaluation of e ffectiveness and the implications of the methods presented are outside the scope of the present work and are subjects of thorough future research.

The most used methods include indicator-based tools, frameworks and indexes followed by multicriteria methods. In the reviewed studies, stakeholder participation is proved crucial in the determination of the level of sustainability. However, a systematic assessment of the agricultural machinery's and operation management's contribution to the overall sustainability was not detected in the examined studies. The e ffect of resource use and input managemen<sup>t</sup> is the most usually examined issue in the reviewed studies.

**Author Contributions:** Conceptualization, D.B. and M.G.L.; methodology, M.G.L.; validation, D.B. and C.G.S.; investigation, M.G.L.; data curation, C.G.S.; writing—original draft preparation, M.G.L.; writing—review and editing, D.B. and C.G.S.; visualization, M.G.L.; supervision, D.B.

**Funding:** The work was supported by the project "Research Synergy to address major challenges in the nexus: energy–environment–agricultural production (Food, Water, Materials)"—NEXUS, funded by the Greek Secretariat for Research and Technology (GSRT)—Pr. No. MIS 5002496.

**Conflicts of Interest:** The authors declare no conflicts of interest.
