Agricultural Pollution

Prof. Kathy Segerson responds to the growing challenges of pollution from the agricultural sector

Agricultural pollution

Agriculture is a critical sector in many world economies and likely to play an increasingly important role as the world strives to feed an estimated population of more than 9 billion people by 2050. In addition, and as incomes rise, the demand for agricultural products is changing, with animal protein playing an increasingly important role in diets in some countries. Yet, agricultural production, including meat production, is also a major source of environmental degradation throughout the world.

The extent of agriculture’s impact on the environment varies with the types of products produced, the production processes that are used, and the scale of production. Nonetheless, agriculture has been identified as a major source of water quality impairment in many countries and regions, including rich countries (such as the United States, Australia, and countries in Europe) and also emerging economies (such as China, Thailand, and the Philippines). Over the coming decades, policy-makers in these nations will face the burgeoning challenge of balancing the demand for agricultural output and specific agricultural products against protection of water and other environmental resources that are both essential for maintaining production and at risk from it. Input from both economists and natural scientists will play a critical role in meeting that challenge.

Sources and Impacts of Agricultural Pollution

The environmental footprint of agriculture stems from a variety of sources. Modern day (industrialized) agricultural is currently heavily dependent on the use of pesticides and fertilizers (nitrogen and phosphorous) to increase production. Yet, depending on how, when, and in what quantities these inputs are applied, they can leach into groundwater or run off into surface waters, contributing to both local and regional water pollution. In addition, soil erosion stemming from agricultural lands can lead to sediment build-up in streams, lakes and estuaries, while runoff from irrigation can carry contaminants (including naturally occurring salts) to these same waterbodies.

Animal waste is a key source of both nutrient pollution and contamination from pathogens such as bacteria and viruses. Further, agriculture is a significant contributor to greenhouse gas emissions, both through livestock production and through the clearing of forested land for conversion to agricultural uses. The associated impacts include: eutrophication (or, in extreme cases, hypoxia) and algal blooms in water bodies, increased siltation and loss of habitat, reduced water clarity, water-borne illnesses or diseases, increased salinity, and climate change.

Reducing Agricultural Pollution

The environmental impacts of agriculture can be reduced by changes in how, what and how much is produced. At the farm level, a number of best management conservation practices exist that can be adopted. For example, conservation tillage practices can reduce soil erosion and runoff from fields, while changes in manure storage and spreading or livestock feeds can reduce the environmental impacts of livestock waste management. More targeted use of fertilizers, pesticides and irrigation water, as well as the use of terracing and buffer strips, can also reduce agriculture’s impact on water quality.

The Policy Challenge

Although there are many ways in which agricultural pollution can be reduced, inducing farmers to adopt environmentally-friendly production practices is a challenge. In some (but not all) cases, less polluting practices increase costs. If there is not some corresponding benefit realized by those farmers, they will have no incentive to switch to more sustainable practices. And even when the associated costs are small (or even negative), farmers may be reluctant to change due to lack of information, risk aversion, or interactions with other governmental program benefits. As a result, designing policies to reduce agriculture’s environmental footprint can be difficult, particularly when policymakers are reluctant to impose costs on farmers because of concerns about the impact on agricultural output, competitiveness, employment or other considerations.

While policy-makers must ultimately decide on how to balance these different objectives, environmental economists can play a critical role in enhancing the understanding of how to create incentives for agricultural producers to adopt practices that protect soil, water and land resources in a cost-effective way. For example, my work has identified cost-effective policy mechanisms that recognize the unique characteristics of agricultural pollution and provide incentives for groups of farmers to collectively address water quality concerns in their local waterbodies. Related work has also provided policy guidance on the conditions under which reliance on voluntary approaches to respond to these concerns is likely to be effective. Thus, in addition to research on the design of effective best management practices, research by economists to identify potential barriers to adoption of those practices and policies to overcome those barriers. Such research and policy advice is essential to maintain and enhance agricultural production while at the same time protecting our environment.

Kathy is a Board of Trustees Distinguished Professor and Alumni Association Distinguished Professor of Economics at the University of Connecticut.

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