Modelling complex livestock-agricultural systems at a regional scale : A case study in La Reunion

Réunion Island, situated in the Indian Ocean, presents a unique case study to model regional bio-economic parameters of the dairy industry. It is a good example of a closed system for movement of animals, available labour, consumption of products, and available land. The present study models the dairy sector at a regional (island) level, in close collaboration with key stakeholders, to study the impact of new agricultural policies in terms of changes to subsidy norms, price fluctuations and environment, with reference to nitrogen excess. The model can be used to generate a number of scenarios, to explore the effects of various industry controls, such as fixing the stocking rate according to EU norms, increasing or reducing the milk subsidy, intensification (such as an increase in milk production to 40 million litres per year) and labour and price constraints (such as an increase or reduction in the milk price or a reduction in labour hours). The model is being consulted by the local dairy cooperative as a discussion support tool at a regional scale to look at implications of expanding the sector and its economic, environmental and social impact. (Résumé d'auteur

Combining interactive multiple goal linear programming with an inter-stakeholder communication matrix to generate land use options

An Interactive Multiple Goal Linear Programming (IMGLP) model is developed that considers objectives of multiple stakeholders, i.e. different farmer groups, district agricultural officers and agricultural scientists for agricultural land use analysis. The analysis focuses on crop selection; considering irrigated and non-irrigated crops such as rice, sugarcane, sorghum, cotton, millet, pulses and groundnut. Interests of the most important stakeholders, farmers, policy makers and water users association are investigated. Important objectives of the farmers are increased income and retaining paddy area; of the policy makers (Agricultural Department) increased farmers’ income, maintaining rural employment, improve water-use efficiency, reduce fertiliser and biocide use and discourage farmers from cultivating marginal lands; of the water users association optimising water use. Scenarios have been constructed by combining objectives and constraints. A Stakeholder Communication Matrix (SCM) indicating the level of communication and information flow among stakeholders in the district was generated after a Participatory Rural Appraisal (PRA). Results of the scenarios generated with the IMGLP model were compared with the matrix. The relevance of analysing the results of the scenarios generated with the IMGLP model in the context of the SCM is illustrated for a sample set of scenarios. Scenario 1 (S1), where both the paddy area and the agricultural area are retained at the current level, is preferred by the farmers. However, the Agricultural Department would identify more easily with S10 in which the paddy area is reduced by 50% and the agricultural area by 20%, in accordance with the policy of limiting the area of high water-demanding crops and dissuading farmers from cultivating marginal lands, while the water users association would prefer S12, where water use is minimised by expanding the area of crops that are relatively less water-demanding. Income in S12 is 22% lower than in S1, while water use is 36% lower, and there is a significant reduction in biocide use. The conflict between S1 and S10 is compounded by the fact that communication between small-scale farmers and the Agricultural Department is relatively weak. Analysing the scenarios in the context of the SCM is useful to gain insight into the interactions among stakeholders in the system and take curative measures if required for improved communication. While the IMGLP model considers the bio-economics of the land use system, the SCM describes its social aspects, which may be critical for successful implementation of the IMGLP model

Modelling farmers action: decision rules capture methodology and formalisation structure: a case of biomass flow operations in dairy farms of a tropical island

International audienceStudies on decision-making processes are generally aimed at identifying farmers' needs and predicting farmers' reactions to technical innovations. In the present paper we study these decision-making processes, with reference to dairy farms, to build a whole-farm computer model (WFM) which simulates farmers' actions. In this study, (i) a multi-tool and multi-step methodology is proposed, which can also be qualified as an iterative and interactive methodology to reveal decision rules and (ii) a generic structure to formalise how action is conducted, tenned 'structure for action modelling' (SAM). In the case of forage crop-dairy cattle systems, we have tested the current methodology to capture the decision rules and the SAM to represent action concerning farm management. An 'immersion' approach, inspired by the ethnographic approach has been adapted to access operational technical decisions (taken on a daily basis). This study helped in understanding how detailed and large approaches can be complementary and can facilitate identification of what can be generalised in a conceptual model. To define the generic structure (SAM), a set of descriptive variables concerning technical operations has been selected. The conceptual model generated is composed of decision rules reconstructed by researchers with farmers' committed participation. The validation method is based on participatory approaches and on comparing of actions simulated by the model with practices on the ground. Not contesting the fact that farmers plan their action, this study also revealed the importance of adjustments in action. For example, 20 to 55% of the time the planned food ration is not distributed to the milking cows because of forage unavailability. We also discuss how this structure can facilitate integration of decision mechanisms in biophysical models and how such an integration of adjustment decision rules can produce more realistic simulations of technical actions. Error of biotechnical evaluations done by the WFM is reduced from about 25% to about 10% with the application of the proposed method