Jacques Wery

An improved methodology for integrated crop management systems

Designing innovative combinations of techniques to improve the sustainability of a cropping system is a major challenge in many regions of the world. The available techniques are often added together, and assessed for yield only, rather than combined in an integrated approach. We than developed here a methodology to design and assess a sustainable crop management system adapted to a specific set of constraints. Based on the prototyping approach, this methodology takes advantage of expert knowledge on cotton cropping techniques such as no-till, cover crop, varieties and growth regulator, with innovative potential but which are not yet properly simulated by actual crop models. It involves four successive steps: (1) identification of the local sets of constraints to crop production, and selection of relevant criteria for sustainability assessment, (2) elaboration of a cropping system prototype and its assessment indicators adapted to a target set of constraints, (3) on-station assessment and adjustment of the prototype, and (4) on-farm evaluation and adjustment of the prototype. We describe here the methodology, and how its first three steps were implemented to build and test a prototype for late-planted cotton with low input availability in West Africa. A new cropping system was designed, which included new genotypes, increased plant stand, lower rates of fertilisers and the use of herbicides and growth regulators. Fourteen indicators were selected to assess the economic, environmental and social performance of the prototype. The prototype was then tested in Mali, Cameroon, and Benin in 2002 and 2003. Our findings show that this prototype improved farmers’ income by about +35% in 2002 and +20% in 2003, and increased labour productivity by about +5 to +20%. It achieved a satisfactory environmental performance, similar to the control, with positive mineral balances. The prototype still requires extra labour, skill and money to implement, and therefore requires further adjustment.

Multiple cropping systems as drivers for providing multiple ecosystem services: from concepts to design

Provisioning services, such as the production of food, feed, and fiber, have always been the main focus of agriculture. Since the 1950s, intensive cropping systems based on the cultivation of a single crop or a single cultivar, in simplified rotations or monocultures, and relying on extensive use of agrochemical inputs have been preferred to more diverse, self-sustaining cropping systems, regardless of the environmental consequences. However, there is increasing evidence that such intensive agroecosystems have led to a decline in biodiversity as well as threatening the environment and have damaged a number of ecosystem services such as the biogeochemical nutrient cycles and the regulation of climate and water quality. Consequently, the current challenge facing agriculture is to ensure the future of food production while reducing the use of inputs and limiting environmental impacts and the loss of biodiversity. Here, we review examples of multiple cropping systems that aim to use biotic interactions to reduce chemical inputs and provide more ecosystem services than just provisioning. Our main findings are the identification of underlying ecological processes and management strategies related to the provision of pairs of ecosystem services namely food production and a regulation service. We also found gaps between ecological knowledge and the constraints of agricultural practices in taking account of the interactions and possible trade-offs between multiple ecosystem services as well as socioeconomic constraints. We present guidelines for the design of multiple cropping systems combining ecological, agricultural, and genetic concepts and approaches.

A modelling framework to support farmers in designing agricultural production systems

Given the new challenges confronting world agriculture, innovative production systems need to be designed at the farm level. As experiments are not easy to conduct at this level, modelling is required to evaluate ex-ante the multiple impacts of proposed innovations. A conceptual framework based on three sub-systems (biophysical, technical, and decisional) interacting within the farm is proposed to guide this process. The advantages and limitations of the framework are illustrated with three examples. The first describes a conceptual, rule-based model representing management decisions for the cultivation of salad in southern France. The second uses a computerized model of the three sub-systems to study irrigation management strategies on farms producing hay in southern France. The third presents a spreadsheet model designed to assist dairy farms in Morocco to define new livestock and forage system strategies. The lessons learned concern the modelling process, the fit between the type of model and its use, and the advantage of involving stakeholders in the design process of tools and innovations.

High temperature and water deficit may reduce seed number in field pea purely by decreasing plant growth rate

Seed number, the most variable yield component of legumes is strongly affected by heat stress (HS) and water deficit (WD). The objective of this paper is to investigate whether HS and WD reduced seed number in field pea through their negative effects on biomass production rather than by specific effects on the developing reproductive organs. Several field and glasshouse experiments were carried out in southern France, in which HS and / or WD of various intensities, durations and positions in the plant lifecycle were imposed on several pea cultivars. WD and HS reduced seed number, in an intensity-dependent manner. They also changed the distribution of seeds along the stem. Plants subjected to WD and mild HS had more seeds on the basal phytomers than did control plants, making it possible to exclude direct effects of stress on seed development. In contrast, severe HS resulted in the immediate abortion of reproductive organs. WD and HS also decreased net photosynthesis (Pn), but only during the period of constraint. Quantitative relationships between Pn and soil water status and between Pn and leaf temperature were established. Nevertheless, in all cases there was a single linear relationship between final seed number and plant growth rate during the critical period for seed set (from the beginning of flowering to the beginning of seed fill for the last seed-bearing phytomer). This reflects the reproductive plasticity of pea, which adjusts the number of reproductive sinks in an apparent balance with assimilate availability in the plant.

A component-Based Framework for Simulating Agricultural Production and Externalities

Although existing simulation tools can be used to study the impact of agricultural management on production activities in specific environments, they suffer from several limitations. They are largely specialized for specific production activities: arable crops/cropping systems, grassland, orchards, agro-forestry, livestock etc. Also, they often have a restricted ability to simulate system externalities which may have a negative environmental impact. Furthermore, the structure of such systems neither allows an easy plug-in of modules for other agricultural production activities, nor the use of alternative components for simulating processes. Finally, such systems are proprietary systems of either research groups or projects which inhibits further development by third parties.

Prospective and participatory integrated assessment of agricultural systems from farm to regional scales: Comparison of three modeling approaches

Evaluating the impacts of the development of alternative agricultural systems, such as organic or low-input cropping systems, in the context of an agricultural region requires the use of specific tools and methodologies. They should allow a prospective (using scenarios), multi-scale (taking into account the field, farm and regional level), integrated (notably multicriteria) and participatory assessment, abbreviated PIAAS (for Participatory Integrated Assessment of Agricultural System). In this paper, we compare the possible contribution to PIAAS of three modeling approaches i.e. Bio-Economic Modeling (BEM), Agent-Based Modeling (ABM) and statistical Land-Use/Land Cover Change (LUCC) models. After a presentation of each approach, we analyze their advantages and drawbacks, and identify their possible complementarities for PIAAS. Statistical LUCC modeling is a suitable approach for multi-scale analysis of past changes and can be used to start discussion about the futures with stakeholders. BEM and ABM approaches have complementary features for scenarios assessment at different scales. While ABM has been widely used for participatory assessment, BEM has been rarely used satisfactorily in a participatory manner. On the basis of these results, we propose to combine these three approaches in a framework targeted to PIAAS.

CROSPAL, software that uses agronomic expert knowledge to assist modules selection for crop growth simulation

Crop growth models are used for a wide range of objectives. For each objective a specific model has to be developed, because the reusability of a model is often limited by the necessity of a fundamental restructuring to adapt it to a different objective. To overcome this limitation, we developed a method to facilitate model restructuring by a novel combination of software technology with expert knowledge. This resulted in the decision-making software application CROSPAL (CROp Simulator: Picking and Assembling Libraries). CROSPAL includes (1) a library of processes each containing different modelling approaches for each crop physiological process and (2) a procedure based on expert knowledge of how to combine the different processes for the objective of the simulation. A brief overview of the state of the art in crop modelling is presented, followed by an account of the developed concept to improve flexibility in crop modelling considering expert knowledge. We describe the design of the software and how expert knowledge is integrated. The use of CROSPAL is illustrated for the modelling of crop phenology. We conclude that CROSPAL is a helpful tool to improve flexibility in crop modelling considering expert knowledge but further development and evaluation is required to extend its range of application to more processes and issues crop modelling is presently addressing.

Experiment-based prototyping to design and assess cotton management systems in West Africa

Designing innovative combinations of techniques to improve the sustainability of cropping systems in poor countries is a major challenge. Here, we developed a prototyping methodology to design, assess and adapt a crop management system for a specific set of constraints. It was applied in Mali with the aim of designing innovative prototypes of cotton management systems to be further tested and adapted by farmers. The prototype aimed at shortening the cotton cycle to overlap the rainy season. The prototype is particularly suited for late sowing and for regions where rainfall is often insufficient. We propose a conceptual model that organizes technical interventions to shorten the cotton cycle. We developed a set of indicators to evaluate the relevance of each modified technical intervention, by comparison with current farmer practices. We evaluated the overall performances of the prototype by taking into account economic, environmental and social factors. The prototype was tested and adjusted in six trials between 2002 and 2004. Our results show that the cotton growth cycle was reduced by 15 days on average, mainly through the shortening of the flowering period. The combination of much higher stand density than currently applied in the region and application of the growth regulator mepiquat chloride produced a much higher number of bolls per hectare of +69%. The prototype produced higher seed-cotton yields, of +44% on average, and much higher gross margin than the standard cotton management system. The method was therefore successful in designing a new cotton management system that helps farmers to adapt to diverse cropping conditions.

Evaluating integrated assessment tools for policy support

Integrated Assessment Modelling tools are complex tools requiring specific evaluation methodologies. Based on the example of the SEAMLESS-Integrated framework, we show how the conceptual, technical and system evaluation steps of the different components (procedures, quantitative models, graphic user interfaces) were performed by a multidisciplinary team. To make the not-yet-available tool real, mock-up and test cases were mobilized throughout the development process in order to integrate final end-users in the evaluation process. The main lessons from the project are that the evaluation required: (i) the use of prototypes to advance properly in the design and testing (spiral methodology); (ii) the use of case studies to stick to the end-users requirements; (iii) a proper timing of development and delivery in order to keep on schedule and leave time to the evaluation process; (iv) a multidisciplinary team of evaluators as tools are of diverse types; and (v) that it is difficult to keep independence between testers, end-users and modellers in order to guaranty transparency in the development and evaluation process.

Impact assessment of climate change on farming systems in the South Mediterranean area: a Tunisian case study

This study considers a quantitative approach for assessing the performance of Tunisian farming systems to face climate change. It is based on the resilience concept and the calculation, with a modelling chain, of three indicators: land stock, labour stock, and income flux. Two system states, “base” and “climate change”, and a time horizon of 2010–2025, are developed and compared for representative farming systems. The study shows that 55% of the farming systems were identified as being resilient to climate change. They are diversified and mostly grow cereals, vegetables, and forage crops combined with livestock, increasing their capability to mitigate climate change by reorganizing crop activities. 35% of the farms identified as being non-resilient are dominated by orchards, or cereals and orchards. They showed an important drop in farm income (−45%), mainly due to their inability to adapt their cropping systems to water stress and soil salinity. Finally, only 10% were identified as being poorly resilient farming systems. Those farms have mainly intensified cereal cropping systems based on a strategy of purchasing land to increase the surface area of profitable activities (forage and livestock). Overall, the methodology can be adapted for other dry land areas in the Mediterranean region and help experts and policy-makers to propose and test strategies for adapting to climate change.