Agroecology is a holistic approach that incorporates ecological, health, social, and economic considerations into agricultural and food systems design and implementation. Agroecology can be applied at the field, farm and whole food system scale (Wezel et al., 2009; Wezel and Soldat 2009). As a scientific and policy approach to transform the food system, agroecology has gained greater recognition, including as one of four flagship eco-schemes of the European Common Agricultural Policy (European Union, 2020), as a means to address environmental and social issues within food systems by the United Nations (HLPE, 2019) and the Intergovernmental Panel on Climate Change (Mbow et al., 2019). Social movements such as the international peasant organization La Vía Campesina advocate agroecology as a means to ensure food sovereignty (Pimbert 2018). Agroforestry, organic agriculture and permaculture can all fall under the category of farm-scale agroecological approaches (HLPE 2019). Some critics have raised concerns, however, about the implications of using agroecology to improve food security and nutrition (FSN). This review examines the evidence for whether agroecological practices can improve FSN. Previous reviews examined evidence for diversified farming systems and organic agriculture's impacts on yield and other ecosystem service outcomes (Ponisio et al., 2015; Reganold and Wachter 2016; Müller et al., 2017) as well as whether diversified systems influence FSN (Jones 2017; Pellegrini and Tasciotti, 2014, Pellegrini and Tasciotti, 2014; Powell et al., 2015; Sibhatu and Qaim 2018). No review so far uses the holistic concept of agroecology and the evidence of agroecological practices' impact on FSN. This review contributes to this knowledge gap.
Agroecological practices aim to optimize ecological processes, environmental and public health and well-being, and minimize social-ecological costs from agriculture such as soil degradation, water contamination, greenhouse gas emissions, exhaustion of nonrenewable resources, and inequitable social structures (HLPE 2019; Wezel 2017; Wezel et al., 2014; Dumont et al., 2013). Relying on principles rather than standardized practices, agroecological farming systems vary based on agroecosystem and socio-cultural context. A non-exhaustive list of the agroecological principles includes co-creation of knowledge, economic diversification, soil and animal health, input reduction, biodiversity, recycling, fairness and connectivity (Wezel et al., 2020). In agroecological food and farming systems, these principles translate into certain agricultural practices, marketing approaches, and food system governance.
Since agroecology encompasses a range of principles that vary in both scale and timeframe, transitions to agroecology have been depicted as a series of levels, from adoption of farming practices and cropping systems to more complex and comprehensive food system redesign (Gliessman 2014). Field-level changes based on principles of soil management and animal health can move incrementally towards an agroecological approach by enhancing efficiency of non-renewable inputs and through substitution, such as replacing synthetic fertilizers with organic soil amendments (Hill and MacRae 1995). Agroecological transitions involve more substantial farm-scale re-design centered around principles of diversity, nutrient recycling and animal health (HLPE 2019). Farm- and community-level changes are supported when social values are incorporated into food system design; for example, when culturally important foods are reintroduced or gender equity improves at the household level. Food-system transformation may occur when principles of fairness and participation are implemented through reconnecting producers and consumers and supporting food justice. Notably, this process is nonlinear and systems do not necessarily transition in sequential steps.Food security and nutrition (text box).
The United Nations has defined global food security as a scenario in which “all people have physical and economic access to sufficient, safe and nutritious food that meets their food preferences and dietary needs for an active and healthy life” (FAO 1996). Nutrition is an integral, multi-dimensional aspect of food security that includes adequate diet, health services, sanitation, proper childcare and feeding practices (HLPE 2017). FSN are broad concepts that can be applied at the global, national, regional, household and individual level. National or global indicators such as per capita dietary food energy supply derived from aggregated data, however, often fail to capture the determinants of food insecurity below the national level (Jones et al., 2013). National and global indicators do not effectively capture the food security dimensions of utilization (Leroy et al., 2015) or power dynamics that affect control over food at the community, household and individual levels (Rocha 2009). As such, a global or national level of analysis would not be fine-grained enough to assess the impact of specific approaches such as agroecology on FSN. In this study we focus on evidence of improved FSN at a regional, household and individual scale.
Most literature related to agroecology assumes farm-level pathways will lead to improved FSN, primarily for smallholder farm households. Recent estimates suggest that smallholder farms (often defined as < 2 ha) make up 80% of all farms globally (Samberg et al., 2016). Globally, small and medium farms provide significant proportions of diverse food groups (e.g., vegetables, fruits, pulses), thereby contributing to human nutrition (Herrero et al., 2017). At the same time, smallholder farming households make up a significant proportion of the world's chronically food insecure population (HLPE, 2013). Direct consumption, agricultural income, and changes in gender relations are recognized as the primary household-level pathways most immediately responsible for FSN improvements (Carletto et al., 2013; Herforth and Harris 2014).
Complex adoption of agroecology can potentially lead to FSN improvements by changing outputs (what is produced) and generating mechanisms (processes and actions) that influence FSN pathways, when adhering to principles that increase agroecosystem health and resilience and transform food system governance to be based on cultural and social values, (Carletto et al., 2013; Herforth and Harris 2014). There is considerable variation in the extent to which food and farming systems implement agroecological principles, with the ecological, socio-economic, and political context in which a farm operates shaping whether more incremental or transformative approaches to agroecology are practiced.
Fig. 1 depicts how diverse forms of agroecology could present different possibilities for FSN impact, generating a variety of outcomes and mechanisms. Depending on the scale at which agroecological principles are applied (denoted in Fig. 1 by the inner and outer rings), certain mechanisms and outputs (the spokes of the rings) will be more relevant. While agroecological principles and related mechanisms applied at the household scale can reinforce those at the community-level, the extent of the FSN impact may depend on the extent of adoption. For example, farm-level agroecological practices could provide in- and around-field habitat for wild flora and fauna, linking household-level agroecological adoption to landscape-level biodiversity; however, the impact on biodiversity and the ecosystem services this diversity provides, such as pollination, will be minimal if surrounding households practice conventional monocropping (Ramos et al., 2018).
Principles applied at the community/landscape level will generally strengthen and reinforce household-level ones. In a community with established farmers’ networks, for example, individual households could benefit from exchanging knowledge about food preparation and preservation (Bezner Kerr et al., 2019a), effective pest management strategies, or techniques to improve soil quality. Principles more relevant to agroecosystem health and resilience can work synergistically with those pertaining to values-based food system governance, and vice versa. Increasing productivity at a household-level through improved soil, crop, and animal health may bolster food sharing networks, with social-practices of reciprocity redistributing resources within the community. Some principles, if applied at the community or farm-level, can themselves act as mechanisms of food security improvement: equitable land and resource governance, and input reduction directly influence FSN pathways.
This review summarizes available evidence on how agroecological approaches, characterized by considerable variation in the scale and extent to which principles are applied, influence FSN. The objectives of the study are to: 1) summarize all research between 1998 and 2019 that demonstrates a relationship between agroecology and FSN; 2) qualitatively describe the strength of the evidence (+, +/− and -), and 3) identify research gaps. The review considered direct (improved quality, quantity and distribution of agricultural products) and indirect effects of agroecological practices including, for example, how more equitable social relations may influence child feeding practices, labor distribution within households, and seed sharing networks. Other indirect effects are environmental improvements such as soil organic matter content or water quality. These capacities may either be direct (household consumption) or indirect (greater market access) — each impacting variety and quantity of food.