Laurence Guichard

Agri-Environmental Indicators to Assess Cropping and Farming Systems: A Review

Environmental impacts of agriculture cannot be always assessed by using direct measurements. Since the 1990s, numerous agri-environmental indicators were developed to assess the adverse effects of cropping and farming systems in the environment, such as water pollution, soil erosion, and emission of greenhouse gases. Here we present the different types of indicators developed during the last decade and review the progress of the methods used for their development. The application of different groups of indicators is discussed and illustrated by examples in the fields of nitrogen losses and pesticide risk: (1) indicators based on a single or a combination of variables related to farmer practices, (2) indicators derived from operational or more complex simulation models assessing emissions of pollutants, and (3) measured indicators linked directly to environmental impacts. The nitrogen indicator (IN) of the INDIGO method and the MERLIN indicator will be presented and used to illustrate the methodological discussion. We show that a good identification of the end-users, of the practical objectives of the indicator, and of the spatial and temporal scales is essential and should be done at a preliminary step before designing the indicator itself. The possibilities of deriving an indicator from a model and of setting a reference value are discussed. Several methods are also presented to study the sensitivity and the validity of agri-environmental indicators. Finally, several practical recommendations are made. As only few data are usually available at the regional level, several simple indicators should be used for assessing a given impact at this level. When more detailed information is available, indicators based on operational models can be useful to analyse the effects of several factors related to soil, climate, and cropping system on an environmental impact. In experimental studies, we suggest using both measured indicators and model-based indicators.

Comparison of methods to assess the sustainability of agricultural systems. A review

Since the 1990s, numerous agri-environmental indicators and indicator-based methods have been developed to assess the adverse effects of cropping and farming systems such as water pollution by nitrates and pesticides, and gaseous emissions due to nitrogen inputs. This wealth of environmental indicators and assessment methods based on indicators raises issues on the quality of the methods and of the indicators, and on the relevancy of results. Evaluation and comparative studies are therefore needed to answer such issues. Here, we present four recent comparative studies selected for their illustrative value, first, to analyse the methodologies used for comparison of methods, and second, to highlight the main results of the four comparisons. The first study involves 23 indicators to address nitrate leaching. The second study involves 43 indicators to address pesticide risk. The third and fourth studies compare environmental assessment methods based on 4–5 indicators used in French and Upper Rhine plains (France, Germany and Switzerland). Both studies also compare the outputs of the methods and highlight the low degree of convergence between them. The approach proposed in the last study is the most elaborate among the four case studies. It could be used to develop a generic evaluation and comparison methodology. The review of those four case studies shows the need to formalise the methodology underlying any comparison work of indicators or evaluation methods.

Ex ante assessment of the sustainability of alternative cropping systems: implications for using multi-criteria decision-aid methods. A review

Sustainability is a holistic and complex multi-dimensional concept encompassing economic, social and environmental issues, and its assessment is a key step in the implementation of sustainable agricultural systems. Realistic assessments of sustainability require: (1) the integration of diverse information concerning economic, social and environmental objectives; and (2) the handling of conflicting aspects of these objectives as a function of the views and opinions of the individuals involved in the assessment process. The assessment of sustainability is therefore increasingly regarded as a typical decision-making problem that could be handled by multi-criteria decision-aid (MCDA) methods. However, the number and variability of MCDA methods are continually increasing, and these methods are not all equally relevant for sustainability assessment. The demands for such approaches are also rapidly changing, and faster ex ante assessment approaches are required, to address scales currently insufficiently dealt with, such as cropping system level. Researchers regularly carry out comparative analyses of MCDA methods and propose guidelines for the selection of a priori relevant methods for the assessment problem considered. However, many of the selection criteria used are based on technical/operational assumptions that have little to do with the specificities of ex ante sustainability assessment of alternative cropping systems. We attempt here to provide a reasoned comparative review of the main groups of MCDA methods, based on considerations related to those specificities. The following main guidelines emerge from our discussion of these methods: (1) decision rule-based and outranking qualitative MCDA methods should be preferred; (2) different MCDA tools should be used simultaneously, making it possible to evaluate and compare the results obtained; and (3) a relevantly structured group of decision-makers should be established for the selection of tool variants of the choosen MCDA methods, the design/choice of sustainability criteria, and the analysis and interpretation of the evaluation results.

MASC, a qualitative multi-attribute decision model for ex ante assessment of the sustainability of cropping systems

Realistic assessments of sustainability are often viewed as typical decision-making problems requiring multi-criteria decision-aid (MCDA) methods taking into account the conflicting objectives underlying the economic, social and environmental dimensions of sustainability, and the different sources of knowledge representing them. Some MCDA-based studies have resulted in the development of sustainable agricultural systems, but the new challenges facing agriculture and the increasing unpredictability of their driving forces highlight the need for faster ex ante (‘Before-the-event’) assessment frameworks. These frameworks should also (i) provide a more realistic assessment of sustainability, by integrating a wider range of informal knowledge, via the use of qualitative information; (ii) address alternative scales, such as cropping system level, improving granularity for the handling of sustainability issues and (iii) target a larger panel of decision-makers and contexts. We describe here the MASC model, which is at the center of a framework addressing these objectives. The MASC model has at its core a decision tree that breaks the sustainability assessment decisional problem down into simpler units as a function of sustainability dimensional structure (economic, social and environmental), generating a vector of 32 holistic ‘mixed’ (quantitative and qualitative) elementary criteria rating cropping systems. The assessment process involves the calculation of these criteria, their homogenization into qualitative information for input into the model and their aggregation throughout the decision tree based on ‘If-Then’ decision rules, entered by the user. We present the model and describe its first implementation for the evaluation of four cropping systems generated from expert knowledge, and discuss its relevance to the objectives cited above. The MASC model has several advantages over existing methods, due to its ability to handle qualitative information, its transparency, flexibility and feasibility.

Iterative Design and Evaluation of Rule-Based Cropping Systems: Methodology and Case Studies - A Review

The economic and regulatory context of crop production changes rapidly, but concerns about agricultural sustainability, including environmental impacts, are increasing steadily. To cope with complexity and uncertainty, innovative methodologies are required for designing, managing and evaluating prototype cropping systems. A generic approach combining iteratively design of cropping systems and evaluation of their performances is presented in this review article. It includes 5 main steps: (1) defining the set of goals and constraints for each cropping system, (2) identifying a suitable agronomic strategy, (3) formulating the consistent set of technical decision rules, (4) applying and evaluating the rule-based system, and (5) validating or refining the strategy and the rules. This methodology was applied to a range of environmental and production contexts, in a perspective of integrated crop production (ICP) prototyping. Three cropping system experiments conducted in France were brought together to demonstrate the potentialities of this system approach and discuss the methodological bottlenecks to address. The three case studies differed by the context of crop production and resource use: adaptation to limited irrigation water (Toulouse), introduction of innovative cropping systems (Versailles), and substitution of herbicides by non-chemical methods (Dijon). The consequences of the specific objectives in each case study on the experimental design and the evaluation process were discussed. Special attention was paid to the time step of the evaluation process, the duration of the improvement loops when prototyping cropping systems, the global evaluation of the systems and the evaluation of individual decision rules.