Strategies for optimizing the use of pesticides: Integrating farmers’ decision-making with dynamic risk assessment models
Case study: Vereda la Hoya, Tunja, Colombia

Regina Schöll, Prof. Dr. Claudia R. Binder (SIE University of Zürich) Jaime Diaz, UNIBOYACA

Abstract
The main objective of this PhD thesis is to derive and assess strategies for optimizing the use of pesticides. Thereby, the case of potato growing farmers in Vereda La Hoya (Tunja, Colombia) gave the applied context. To fulfill this objective first the present perception, then the future visions of farmers and experts were analyzed. Finally the present perception and the future visions of farmers’ system-perspectives were compared and their differences were discussed in relation to decisionmaking.
Despite the improvements in plant protection the control of plant pests still entails substantial use of pesticides. As known from several previous studies the inappropriate pesticide application can lead to high environmental damages as for example degradation and contamination of soils, as well as deterioration of the biodiversity of the soil system. Pesticides can induce a chain of direct responses leading to neuromuscular blockage. Many chlorinates can induce liver changes, kidney changes and depression of the central nervous system. Further health effects, caused by the active components of pesticides, are headache, nausea, fatigue, eye irrigation and skin rash.
The problems of these misuse categories all relate to problems of classical decision-making theory and specifically to risk perception theory. Therefore to tackle the presented pesticide problem the following research questions were investigated. 1) How do farmers’ mental models and livelihood context, affect their risk perception concerning pesticide application? 2) How do farmers’ livelihood context and farmers’ risk perception, reflected in their mental models, influence farmers future vision of pesticide application? 3) How can farmers’ risk perception and future visions be compared and what conclusion can be drawn for decision-making? The thesis is organized in three parts dealing with the
different aspects of pesticide use and referring to one research question respectively.
In the first part the Structural Mental Model Approach (SMMA) was developed. The SMMA is a methodological approach aimed at understanding differences in perception between experts and farmers regarding the various risks farmers are confronted with. In the SMMA, the Sustainable Livelihood Framework (SLF) is combined with the Mental Model Approach (MMA). The approach consists of three steps: (i) definition and weighting of the different livelihood capitals; (ii) analysis of livelihood dynamics, and (iii) definition of the social capital.
By applying the SMMA we were also able to identify reasons for the divergence of experts’ and farmers’ MMs. Of major importance are the following factors: i) culture and tradition; ii) trust in the source of information and iii) feedback on knowledge.
In the second part farmers’ future visions concerning pesticide management were found. To achieve this goal the Structural Mental Model Approach was adapted to the future context (Future- SMMA). It was found that farmers consider social and environmental threats and that their visions are optimistic. In additions farmers’ and experts’ perception of external constrains to farmers’ future were compared and it was discovered that the investigated future visions of farmers and experts were inconsistent. Discussing the findings it was concluded from the results that the found inconsistency of future visions were caused by of diverging attitudes towards future scenarios and differing opinions
about who should take responsibility for the knowledge management of the farmers.
Comparing the first two parts of the PhD thesis this third part consists of assessing the similarity of future and present mental models and shed additional light on the topic of dependency of future on present mental models and decision-making concerning pesticide use. By comparing the causal relations it was found that depending on whether the livelihood capitals or the interviewed farmer were investigated the dependency of future on present differed. The four individual capital differed substantially in degree of dependency (natural capital being most and health capital least
dependent). Moreover four different farmer types of future on present dependence were found. Some farmers mostly used the same causal relation (causes and effects) in the present and in the future mental models, whereas other farmers focused more on the causes and a different group of farmers focused more on the effects of causal relations in present and future mental models.

Msc. Jaime Diaz, Department of Environmental Engineering
Universidad de Boyacá (UNIBOYACA)
Carrera 2 est Numero 64-169, Tunja Colombia
Phone::++57 (098) 745 2597 or ++57 (098) 7450000 ext. 5402

jaimediaz@uniboyaca.edu.co

Dipl. Umweltnatw. ETH Regina Schöll, Department of Environmental Sciences
Institute for Human-Environmental Systems (HES)
Haldenbachstr. 44 ETH Zentrum , 8092 Zuerich, Switzerland
Phone: ++41 (044) 6325945
regina.schoell@env.ethz.ch

Figure 1: Pesticide mixing in Vereda la Hoya
 

Figure 2: Farmer Interview in Vereda la Hoya