Bio-economics of agricultural nonpoint source pollution control: Nitrates in southwestern Ontario.

摘要

The main purpose of the study was to provide policy makers and farmers with missing information that will assist them to understand the relationships between agricultural production practices, their effects on N leaching loss to groundwater and the cost-effectiveness of using public policy options for controlling nitrate pollution.; An integrated economic-ecological analytical framework was developed by evaluating the contribution of economic theory in analyzing sustainable agricultural production systems. Applying Lancaster's theory of consumer demand to agroecosystems and the opportunity cost of foregone farm management choices centres around von Mises' human action and the motivation for maintaining a balance between society's environmental quality objectives and farmers' cost effectiveness of achieving these goals.; Empirical studies on diffuse source pollution control from agriculture typically integrate biophysical simulation modelling with an economic farm optimization model The CENTURY model, which has not previously been used to simulate actual multi-crop rotations including varying farm management effects for Canadian agriculture, was calibrated and then used to predict changes in N leaching loss and crop yields under alternative farm management conditions for southwestern Ontario. Reduction of mineral N leached was relatively higher when fertilizer was applied at rates greater than the maximum economic rate of nitrogen fertilization (MERN) than when the rate was less than MERN. This result implies that a design-based policy instrument on N fertilizer might not achieve the desired reduction in leachate while reducing yields. Attempts to reduce NO{dollar}sb3sp{lcub}-{rcub}{dollar}-N leaching when the fertilizer rate is at or below the MERN would only serve to reduce yields and subsequently returns without significantly improving the environmental quality objective.; Results indicate that because the maximum economic rate of N fertilization and the level of N leached to groundwater depend on a variety of farm management practices such as crop choice and crop rotation, and tillage system, on-farm abatement costs also varied with each farming system. Explicit marginal abatement cost curves derived indicate that differences in abatement costs among farming systems were greater, hence choice of cost-effective farming system for mitigating N leaching loss is critical, under more stringent standards than at higher pollution levels. Implementing excessive, stringent uniform (rather than targeted) emissions and input taxes generates considerable efficiency loss to society, in addition to making farming systems unprofitable.