However, judging the sustainability of introducing such changes into farming systems has, until recently, been somewhat problematic. For one thing, testing any changes in the field is time-consuming and expensive. As a consequence, truly innovative systems have often remained untested because of the cost of conducting the necessary experiments.

Furthermore, there is the complex interplay between all the different factors that affect agriculture. Besides meteorological variables such as rainfall and sunshine hours, there are the differences in soil, landscape and the availability of agricultural advice and subsidies, to name just a few, that all play a role in deciding whether changes in farming systems will be sustainable.

Figure 1: General description of DEXiPM (b) and how it is included in the loop for the design of innovative cropping systems (a) (from Lançon et al., 2007).

And while there is widespread agreement that changes in European agriculture should be sustainable, the concept of sustainability itself is not simple. There can often be contradictions between different sustainability requirements: a cropping system that is economically sustainable may not be environmentally sustainable, for example, making it difficult to conceive cropping systems that meet all sustainability needs.

Over the past 20 years, making sense of such complex matters has become easier thanks to the development of computer modelling programs, and ENDURE is seeking to improve decision-making in the agricultural sphere through the development of DEXiPM.

DEXiPM has been developed by scientists at INRA, France’s National Institute for Agricultural Research, and is a modelling program which makes it possible to conduct ex ante (before the event) qualitative assessments of the sustainability of new systems using a range of criteria (see Figure 1).

The ability to perform these assessments is particularly useful for ENDURE’s system case study teams. These multidisciplinary research teams are currently studying orchard and arable crop systems with the aim of identifying and describing current systems (those commonly found in Europe), advanced systems (such as those employing Integrated Pest Management (IPM) and organic systems) and innovative systems (using innovative combinations of existing practices or new technologies or practices).

The ability to analyse and compare these systems using DEXiPM should prove valuable not only in estimating the overall sustainability of the systems but, more importantly, in shedding light on the value of all the criteria under analysis. Thus further improvements can be discussed and tested, resulting in better proposals for innovative systems. And because the context (political, social, economical etc) is taken into account in the model, DEXiPM can also assess those innovative systems which may not be feasible or efficient today, but which might be sustainable 'tomorrow' in a different context.

How DEXiPM works

Figure 2: DEXiPM hierarchical tree (upper part) for multi-criteria assessment of cropping systems.

DEXiPM is based on the DEXi program produced by researchers in Slovenia. This computer program is designed to help decision making where multiple attributes need to be taken into consideration (see the Jozef Stefan Institute website for more details). It enables users to evaluate different options and thus to select the best option according to the goals of the decision maker.

DEXiPM is what is called a hierarchical qualitative multi-criteria model. Multi-criteria is self-explanatory in that the program takes in a range of criteria. Hierarchical refers to the way these criteria are structured, with the program offering an indication of overall sustainability, measured in environmental, social and economic sustainability, which is then broken down into increasingly specific criteria. Qualitative refers to the fact the program uses qualitative attributes (symbolic) rather than quantitative (numeric) ones.

Figure 3: Assessment of the overall sustainability for two cropping systems. CS: winter crop-based current system; IS1b: winter crop-based innovative system; ECO: economical sustainability; ENV: environmental sustainability; SOC: social sustainability.

For example, to arrive at a measure of environmental sustainability the program takes into account such criteria as resource use, environmental quality and aerial biodiversity. To arrive at a measure of resource use, the program takes into account criteria such as use of energy, water, mineral fertilizers and land (see Figure 2).

To illustrate how this works in practice, INRA researchers have examined the example of two cropping systems in the French region of Bourgogne. The current cropping system is based on a crop sequence of winter oilseed rape, winter wheat and winter barley and the crop protection strategy is mainly based on pesticides. An innovative system is then proposed, using a crop sequence of winter oilseed rape, winter wheat, spring barley, alfalfa, alfalfa, winter wheat, mustard, sunflower and triticale. These crops will be sown at lower densities and sowing dates are changed to control weeds, diseases, insects and slugs.

Figure 4: Assessment of the aerial and above soil biodiversity for two cropping systems. CS: winter crop-based current system; IS2b winter crop-based innovative system; NE: natural enemies.

Examining the overall sustainability for these two systems reveals little difference (see Figure 3) but further investigation down the ‘tree’ of attributes provides a clear illustration of how DEXiPM can shed light on the relative advantages or disadvantages of innovative systems.

Environmental sustainability, for example, is low for the current system and medium for the advanced system, just one measure of difference, but examine the three attributes aggregated to arrive at these measures and some clear differences can be observed. For example, there is a marked difference in aerial biodiversity (very low in the current system compared to high in the innovative system), which is due to factors such as lower use of pesticides, increased diversification of the crop sequence and landscape management (see Figure 4).

For more information

For further information on DEXiPM, contact ENDURE.

If you found this article interesting, you may want to consult the following articles from the ENDURE archives:

• System case studies: Taking a broader view
• Interview: Pierre Ricci, ENDURE coordinator