Progress in the design of AEIs has been made by initiatives across the institutional spectrum, and many national AEIs are linked to agri-environmental sustainability frameworks adopted by governments at the highest level. One of the prominent criticisms is that these indicators have low capability to effectively counterbalance environmental destruction and unsustainable development, which threaten the well-being of all humanity. Furthermore, there is little research on the improvement of AEIs, and further development of sets of indicators, or even indicator-based research methods, is required to meet the sustainability targets of the agricultural system. Another gap often mentioned in the sustainability indicators literature is that the scientific information conveyed by the indicators is insufficient to produce a change in national decision making or individual behavior
[16]. Therefore, effective AEIs must balance the practical needs of stakeholders with a theoretically sound understanding of agri-environmental sustainability. Consequently, the investigation of stakeholders’ perceptions of AEIs is vital.
Regardless of the precision of the AEIs, which is a subject of debate, they remain a state-of-the-art instrument in assessing the sustainability of farming systems, providing valuable information and even datasets when two or more indicators are combined. Indicators help incorporate agri-environmental knowledge into decision making and help measure the progress toward sustainable development goals
[17]. Practically, it is hard to manage what is not measured, and AEIs more efficiently address the nexus between agriculture and the environment
[18]. Thus, AEIs are valued as the main ingredient in achieving future sustainable agriculture
[18].
From Sustainable Agriculture to Agri-Environmental Indicators
Like the concept of “sustainable development”, “sustainable agriculture” is challenging to interpret and conceptualize, thus complicating its use and implementation [19][20]. Furthermore, an absolute definition of sustainable agriculture is questionable, mainly because there are a range and number of stakeholders [21] with different values and beliefs, and many rural characteristics differ from region to region. Hence, it is important to continue exploring the meaning of agricultural sustainability as a time- and space-specific [22] work-in-progress concept.
A wide range of socioeconomic and environmental indicators have been developed [23][19][24][25][26] to measure the sustainability of agriculture. These helped farmers worldwide to make improvements in the use and management of nutrients, pesticides, energy, and water, and progress in adopting more environmentally beneficial practices, such as conservation tillage, soil nutrient testing, or manure storage [27]. Despite these improvements, there is still more to do, and sustainable agricultural practices will continue to play a significant role in protecting the environment. Thus, to fulfill the purposes, sustainable agriculture was defined as agriculture that “over the long term, enhances the environmental quality and the resource base on which agriculture depends; provides for basic human food and fiber needs; is economically viable; and enhances the quality of life for farmers and society as a whole” ([28] cited by [29]). Practically, agricultural sustainability finally aims to preserve natural resources and the resilience of rural communities by promoting lucrative and community-friendly farming practices and methods [30].
Fernandes and Woodhouse
[31] define AEIs as “estimators of the impact of agricultural practices on the agroecosystem”. Yli-Viikari et al.
[32] consider the AEIs as “tools to address current development paths of agricultural production in broader terms”. The AEIs can help farmers adapt their agricultural practices to be environmentally friendly
[31]. At the broader regional/national level, AEIs can inform the effectiveness of agri-environmental programs and support policy decisions
[33].
As many studies have acknowledged
[34][35][36], AEIs must address the following aspects: description or explanation of the state of spatial systems and its deviation from the natural state; impact assessment of the effect of particular actions on the state of spatial systems and its deviation from the natural state; prediction of future conditions of spatial systems under various scenarios of socio-economic or environmental change; and monitoring to keep track of changes in the state of spatial systems and to support appropriate corrective actions. Nonetheless, the literature dedicated to AEIs highlights several limitations associated with their use. For example, one limitation of the AEIs is data availability and collection
[37].
2. Current Insights
Although agricultural performance has been evaluated during the last 30 years using mainly one criterion, namely “Productivity”
[38], a broader perspective is needed to better reflect the environmental concerns and human needs. The transition to sustainable agriculture implies a shift from farm-level solutions to a focus on interactions within the entire value chain, from production to consumption
[39]. The demand of the European welfare society, which targets higher agricultural productivity, must meet consumers’ expectations of more environmentally friendly farming products and their concerns for a balanced environment. To understand these new societal needs, researchers have looked beyond that single criterion—productivity—and turned their attention to natural resources, which, together with financial resources, labor force, and technology, are at the basis of agricultural productivity. Consequently, tools such as AEIs have been developed to successfully assess the sustainability of farming systems
[40].
One central idea is that there is still considerable room for improvement in the indicator selection process
[41][42][43]. Additionally, the lack of robust and coherent “procedures for selecting indicators makes it difficult to validate the information provided by those indicators”
[44]. Other referenced studies stressed that a transparent indicator selection process would increase the scientific credibility of environmental assessment
[42][45][46], underlying the need for indicators that can link ecological dimensions with environmental, social, and economic dimensions. Additionally, the AEIs literature review highlighted that AEIs are not yet universal tools for global monitoring of farm sustainability. As many referenced authors argued in the scientific literature, new indicators and indicator-based methods [e.g., DPSIR (drivers, pressures, state, impact, and response model of intervention)] should be developed to address local or regional agri-environmental particularities.
3. Conclusions
One main conclusion is that AEIs must be developed within a transdisciplinary context that brings together agricultural and environmental dimensions to provide the best and most sustainable solutions to the current challenges facing the agricultural system. Furthermore, once the indicators are developed according to local specificity and tested by agri-environmental specialists, they must be integrated into national, regional, and local agricultural policies and strategies.
The possible reluctance of farmers to accept and implement AEIs. Tripartite cooperation between stakeholders—agri-environmental researchers, policymakers, and farmers—is necessary to ensure this approach is successful.
Another aspect that must be acknowledged is that most AEIs refer to only one dimension of sustainable development—the environment. Therefore, to have a broader picture of a sustainable farming system, one must combine different indicators or develop sets of interrelated indicators that approach all three dimensions of sustainability.
Finally, the AEIs play a critical role in highlighting the current and future trends in the state of the environment within the agricultural system (e.g., soil erosion, and pesticide load from soil or water). Consequently, the AEIs can help monitor a farming system and set the priorities for future policy actions.