Dynamic Agricultural Household Bio Economic Simulator Dahbsim Model Description

DAHBSIM is a dynamic, bio-economic model of agricultural households that was designed to be applied to a rural, developing country-setting, for the purpose of addressing questions around the biophysical constraints to on-farm agricultural productivity, and the whole-farm implications of alternative strategies to sustainable agricultural intensification. The model links socio-economic and biophysical aspects, in order to better illustrate the environmental and human welfare implications of different agricultural production practices, as they are influenced by policy-driven changes in prices of inputs or outputs, or by changes in the physical environment.

This book has the purpose of providing the "state of the arts" concerning bio-economic modelling dealing with agricultural systems. In most cases, the contributions use a methodology combining the use of biophysical and economic models, in all cases, an engineering production function approach is totally or partially applied. This practice is being developed in the last years as a response to concrete policy matters: agricultural policies are increasingly combined with environmental and natural resources policies, and this reality involves the need of an integrated assessment, that current economic models are not able to provide.

This book presents the basic model of an agricultural household that underlies most of the case studies undertaken so far. The model assumes that households are price-takers and is therefore recursive. The decisions modeled include those affecting production and the demand for inputs and those affecting consumption and the supply of labor. Comparative results on selected elasticities are presented for a number of economies. The empirical significance of the approach is demonstrated in a comparison of models that treat production and consumption decisions separately and those in which the decisionmaking process is recursive. The book summarizes the implications of agricultural pricing policy for the welfare of farm households, marketed surplus, the demand for nonagricultural goods and services, the rural labor market, budget revenues, and foreign exchange earnings. In addition, it is shown that the basic model can be extended in order to explore the effects of government policy on crop composition, nutritional status, health, saving, and investment and to provide a more comprehensive analysis of the effects on budget revenues and foreign exchange earnings. Methodological topics, primarily the data requirements of the basic model and its extensions, along with aggregation, market interaction, uncertainty, and market imperfections are discussed. The most important methodological issues - the question of the recursive property of these models - is also discussed.

This book takes forward our understanding of agricultural input subsidies in low income countries.