عدم تفکیک و تجانس در تجزیه و تحلیل زراعتی اقتصادی یکپارچه از منبع آلودگی فاقد نقطه نظر

This paper highlights two aspects that are crucial in the management of agricultural nonpoint-source pollution but that are typically not taken into account in applied economic studies. Firstly, production, pollution and abatement are to be treated as non-separable to include control options provided by changes in production practices. Besides, non-separability enables proper account to be taken of the material flow through production processes and changes the perspective on optimal environmental regulations. Secondly, the resolution or level of spatio-temporal aggregation should capture the heterogeneity in the economic and ecological attributes (production condition, fixed but allocatable inputs and technology set) of the individual decision-maker's policies they intend to influence. The implications of non-separability and heterogeneity for empirical studies and for policy are illustrated by two simulation studies on nitrogen and pesticide use in crop farming.

The analysis of agro-ecosystem sustainability requires establishing communication between biophysical and socio-economic disciplines. Interdisciplinary research on sustainability requires identification of the proper spatio-temporal scales to be covered in the analyses, effective communication of concepts, consistent organization of data, translations of concepts and data into integrative models and a structured presentation of model results (Weston and Ruth, 1997). For nonpoint-source pollution these requirements are extensively discussed in the theoretical literature (e.g. Antle and Just, 1992 and Russell and Shogren, 1993), but frequently not met in applied work. For example, Vatn et al. (1997), (p. 208) review examples of policy relevant studies for nonpoint-source pollution from agriculture and conclude that in-depth integration of the various disciplines involved is in fact still very rare.1 More recent publications do not show much improvement in this respect as their main concern is not with further conceptual integration, but particularly with the use of geographic information systems (GIS) to organize data and present results (e.g. Skop and Schou, 1999). The purpose of this paper is to highlight two aspects that are critical in particular in the integrated analysis of control of agricultural nonpoint-source pollution, but that are typically not both2 taken into account in policy relevant work. Firstly, production, pollution and abatement are often treated as separable, which excludes control options provided by changes in production practices and input substitution. Separability also precludes proper account being taken of the material flow through production processes and leads to an unnecessary emphasis on emissions in policy analysis and recommendations. Secondly, for policy analysis it is crucial for the resolution or level of spatio-temporal aggregation to capture the heterogeneity in key economic and ecological attributes of the individual decision-maker's policy intends to influence. Farmers are the agents that decide on production practices, also for the larger ecological or administrative systems for which policy objectives are usually formulated, such as watersheds, aquifers and counties or states. We proceed as follows. Section 2 provides a theoretical discussion of non-separability of production and abatement in the static, non-spatial setting. Section 3 and Section 4 discuss heterogeneity due to variation in productive capacity (resource base, crop and equipment) both in the static and dynamic setting, and Section 5 focuses on scaling up. Section 6 provides two case studies to demonstrate integrated modeling in the econometric setting and the activity analysis/programming setting, respectively. The paper concludes with a discussion and priorities for further research.