Water Pollution from Agriculture: Transatlantic Agriculture & Regulation Working Paper Series: No. 4

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by Peter Linquiti & Zhoudan Xie
October 12, 2017

Produced via a cooperative agreement sponsored by The United States Department of Agriculture

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As part of a cooperative agreement with the United States Department of Agriculture (USDA), the George Washington University Regulatory Studies Center produced a five-chapter report on regulatory differences between the United States (U.S.) and the European Union (EU) and their effects on agricultural production and productivity. Those chapters are published here as a working paper series with five parts. This chapter reviews how the U.S. and EU regulate water pollution from agriculture, particularly nutrient contamination from fertilizer use on crops and from the management of manure from livestock. The chapter first reviews the core environmental problem—the process by which nutrient pollution occurs and the adverse environmental and human health consequences it causes. It also provides a broad overview of the institutions and policy frameworks that shape water quality polices relevant to agriculture in the two jurisdictions and proceeds by characterizing the specific policy instruments used in the U.S. and the EU to implement these broader policy frameworks. The chapter concludes by describing the on-the-ground implementation experience and the degree to which retrospective program evaluations are performed.

Scope of the Environmental Problem

Water pollution from agriculture poses unique challenges for regulators. Agricultural runoff is largely a nonpoint source of pollution and traditional point-source pollution control policies may be unsuitable.Further, wide variations in agricultural practices and local environmental conditions can make it difficult for policymakers to set a single, jurisdiction-wide standard that meets varied needs. Another challenge, not addressed here, is that the agriculture sector, in both the U.S. and EU, has considerable influence in the political sphere.

Nutrient Use in Agriculture

More than anything else, a nutritious diet for humans and animals must include sufficient energy, typically measured in Calories, to support life. It also must include chemical compounds, such as vitamins or essential amino acids that cannot be manufactured metabolically. In contrast, plants derive their energy from sunlight, and they often have metabolic pathways that are capable of making any necessary chemical compounds. For these reasons, a list of plant nutrients generally will focus on the chemical elements that are critical to a plant’s growth. They include non-mineral nutrients and mineral nutrients. Non-mineral nutrients are hydrogen (H), oxygen (O), and carbon (C), which plants obtain from the air[1] and water.

Mineral nutrients can be further divided into macronutrients and micronutrients. Macronutrients refer to nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S), which plants typically require in relatively large amounts, while micronutrients, such as iron (Fe), chloride (Cl), and manganese (Mn), are needed by plants in much smaller amounts. Among these nutrients, nitrogen, phosphorus, and potassium are most important for crop production, and supplementation in the form of intentional addition to the soil can substantially increase crop yield.

Animal wastes often are applied to croplands to provide needed nutrients. Poultry litter tends to be relatively high in phosphorous, and is highly valued where that nutrient tends to be scarce. Waste from hog farms tends to be higher in nitrogen, as does human waste. Treated human waste, called biosolids, may be applied to some crops.

In addition to animal and human waste streams, U.S. and EU agriculture uses synthetic fertilizer on a large scale. Atmospheric nitrogen can be “fixed” using a process invented by the German chemist Fritz Haber. Today, the amount of nitrogen fixed by the Haber process, including a number of nonagricultural uses, has transformed the earth’s natural nitrogen cycle.[2]

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[1]    Nitrogen is also abundant in the air as N2, but is generally not available to plants unless they are legumes. Throughout this chapter, any reference to nitrogen will mean “fixed” nitrogen—that is, nitrogen contained in a chemical compound, often a nitrate, which is metabolically available to plants.

[2]    Galloway, J. N., Townsend, A. R., Erisman, J., Bekunda, M., Cai, Z., Freney, J. R.,…Sutton, M. A. (2008). Transformation of the Nitrogen Cycle: Recent Trends, Questions, and Potential Solutions. Science, 320, 889-892. Retrieved from https://www.researchgate.net/profile/Jan_Willem_Erisman/publication/5363687_Transformation_of_the_Nitrogen_Cycle_Recent_Trends_Questions_and_Potential_Solutions/links/0fcfd5080f64094f9d000000.pdf