Costs and Benefits of Nitrogen and Phosphate Fertilizer Use In the Lake Erie Basin

Introduction

Over the course of the State of Ohio's history, entrepreneurs and farmers have developed a series of new techniques and tools in order to increase agricultural yields and overall food production. By building prosperous communities backed by the hard working ideals of resource extraction and industrial production, Ohio quickly became a haven for Americans and immigrants looking for opportunities westward. As agricultural production increased though, unintended consequences as a result of those new innovations became apparent.

Over the last few decades, algae growth in western Lake Erie has become a constant concern for various stakeholders invested in the environment, society, and economy. This paper will go through an analysis on the history, technology, and processes by which chemical fertilizers induce increased algal growth and therefore affect ecological, human health, and economic systems across western Lake Erie. In addition, the paper will review the benefits of using chemical fertilizers by farmers in Ohio's Lake Erie basin. By compiling research on the costs and benefits of chemical fertilizer use in the western Lake Erie basin, stakeholders will have access to a comprehensive review of externalities associated with agricultural production and eutrophication. In this paper, it was expected that costs incurred on species, the environment, human-health, and the economy are, on an aggregate basis, greater than the benefits gained out of using chemical fertilizers on Ohioan cropland.

The primary limit of this paper's approach and analysis is the qualitative nature of aggregating effects across the environmental, social, and economic spectrums. Additionally, surveys and other data capturing techniques were not used to produce the analysis. Instead, a literature review and compilation of 57 scholarly journal articles, government reports, manuscripts, and news articles were used to produce an overview of the costs and benefits associated with chemical fertilizer use. Recommendations for areas of future investigation were also made with respect to the surveyed research on this subject.

History

Shortly after the American Revolutionary War, Americans looking to expand their territory soon populated the area of what is today known as Ohio. As the 17th state in the union, Ohio, like many other Midwestern states, focused its economy on the production of raw materials and common-pool resources, which were both subtractable and nonèxcludable. These types of goods made it easy for Ohioans to establish local economies that were self-sustaining and efficient. A combination of abundant land, rich soil, and ample water resources made it possible for Ohio to become a hotbed of growth for the early American agricultural industry.

Farming provided the opportunity for Ohio's economy to develop rapidly over the course of the early-mid 19th century. By 1849, Ohio was the largest producer of corn and the second largest producer of wheat in the United States (Knepper, 2003). This also helped contribute towards the increase of Ohio's population, which increased from 42,159 in 1800 to 2,339,511 by 1860 (U.S. Department of Commerce, Census Bureau, 1970).

The diversification of Ohio's economy eventually began to occur after the end of the civil war. Early Ohioan factories were born out of the very agricultural industry that established the state's economy. Industrialized goods were produced in order to complement the existing agricultural economy. For example, iron- manufacturing plants along the shores of Lake Erie were able to create the steel needed for new farming equipment. Advances in agricultural technology also helped increase total crop yields, which helped incur greater profits for farmers. In addition to farmers, investors looking to expand their opportunities were provided with a wealth of both natural resources and human capital, which made newly industrializing cities, such as Toledo and Cleveland, attractive locations to settle in. The economic ecosystem of the region became a flourishing environment for a diverse set of players that had been backed by decades of a developing agricultural industry.

As Ohio became increasingly industrialized, however, the state relied on its agricultural industry less. While specific periods in the 20th century spurred growth for the industry, such as World War I and World War II, agriculture in Ohio had been declining. Despite this decline, farming in the state has remained an essential segment of Ohio's economy during the 20th and 21st centuries. Ohio's agricultural industries today represent over $90 billion USD of the state's total economic output and employ one in seven Ohioans either directly or indirectly (Myers, 2005).

In addition to being a core component of Ohio's economy, the state's geography is also significantly shaped by the agricultural industry. In 1997, approximately 13.6 million acres (52%) of Ohio's 26.4 million acres were agricultural, 7.1 million acres (27%) were forested, and 3.6 million acres (14%) were developed or urban areas (Ohio Legislative Service Commission, 1997). Today, approximately 30% of Lake Erie's surrounding land is cropland, which is significantly greater than any other Great Lake (Ohio Legislative Service Commission, 1997).

Technology & Innovation

America in the mid-1800s was a time of technological innovation and re- development for the agricultural industry. New farming equipment, such as the steel plough, were a major contributor to the economic success of the Midwest. However, it wasn't until the "Green Revolution", that occurred between 1930 and 1970, when agriculture started to become a truly technologically driven industry. During this period, farming technologies that had already existed in many industrialized countries were spread to developing countries, such as Mexico, India, Brazil, and the Philippines.

The one development that has possibly revolutionized the production of food and shifted its supply more than any other has been the continuous improvement of agricultural fertilizers and pesticides. While prioritization for the management of soil fertility had been in place for thousands of years before, the modern science of plant nutrition didn't develop until the 19th century. Malthusian theories of exponential global population growth concurrent with linear food production growth drove scientists to investigate the mechanics of agricultural production greatly, which included comprehensive study within the botanic sciences. Prominent scientists, such as the Dutch chemist, Justus von Liebig, were now performing research and development on an industry that had experienced little advancement since the Middle Ages.

Throughout the modern historic use of fertilizers and pesticides, there have been a series of discoveries that have made them more efficient to produce, less costly, and more effective. This has caused the use of agricultural supplements to increase greatly over time. Today they're commonly used throughout the majority of North American farms. According to the United States Department of Agriculture (USDA), 78% of corn acreage in the United States received phosphate fertilizer in 2010, compared to 90% in Ohio (National Agricultural Statistics Service, 2010). In the same survey, it was found that 97% of corn acreage in the United States received nitrogen fertilizer in 2010, compared to 100% in Ohio. The widespread use of new farming technologies in Ohio, such as chemical fertilizers, has a deep-rooted history and tradition that dates back over centuries.

Soils & Eutrophication

Northern Ohio's soil was formed largely by glaciers and weathering of sedimentary rock (Ohio Department of Natural Resources, 2007). Western Ohio soil also exhibits greater levels of lime, which increases soil pH. This allows soils in western Ohio to generally be more productive and fertile for crops, due to increasing natural acidity to soils over time. Soils along Ohio's northwestern corridor were formed in lake and beach sediments and in glacial till associated with glacial lakes. Because of this, soil horizons in the region typically exhibit high levels of silt and sand within the topsoil. Further west, agricultural land in northern Ohio is characterized by near-level crop fields that contain both drainage ditches and subsurface drains. To the east, soils contain greater clay materials, which provide both coarser textured and steeper soil horizons.

Due to northern Ohio's high level of sand and silt in its soil, the region is highly prone to experiencing drainage issues and eutrophication. The Natural Resources Conservation Service (NCRS) of the USDA defines eutrophication as, "(1) the degradation of water quality due to enrichment by nutrients, primarily Nitrogen (N) and Phosphorus (P), which results in excessive plant (principally algae) growth and decay. When levels of N:P are about 7:1, algae will thrive. Low Dissolved Oxygen (DO) in the water is a common consequence. (2) The process of enrichment of water bodies by nutrients." (Natural Resources Conservation Service, 2011).

While the use of chemical fertilizers can provide immediate adequate nutrition to crops, they are also highly susceptible to leaching through sand and silt based soils, particularly those in northwestern Ohio. Furthermore, 63% of soils further west experience seasonally high water tables that are less than a foot below the surface (Ohio Department of Natural Resources, 2007). A high water table provides easy transportation for leached chemical fertilizers to flow through these water channels, and eventually into western Lake Erie.

Added chemical fertilizers from crop fields that are leached into local water systems eventually end up in the Lake Erie Basin, which consists of watersheds surrounding the lake. While 80% of Lake Erie's water is captured via the Detroit River, 9% is derived from these watersheds (New York State Department of Environmental Conservation, 2005).

Algal Blooms

Through rain and irrigation-caused leaching, agricultural fertilizers containing phosphorus and nitrogen provide water systems with an influx of nutrients. These nutrients help spur the rapid growth and multiplication of aquatic vegetation and algae. Western Lake Erie, in particular, experiences the rapid growth of cyanobacteria, which produce harmful toxins known as microcystins.

Microcystins are a class of toxins that are commonly produced by certain freshwater cyanobacteria. With over 60 microcystin toxins known, they pose major threats to ecosystems as well as drinking and irrigation water supplies (Ramsy et al., 2013). Previous research has validated the positive correlation between phosphorus loading and microcystin concentrations in western Lake Erie (Rinta- Kanto, 2009).

Microcystin Structures

As cyclic peptides, microcystin structures consist of a seven-membered peptide ring that is made up of five non-protein amino acids and two protein amino acids (Schneegurt, 2000). When cyanobacterial cells die, their cell walls burst, releasing the toxins into the water.!

Microcystin Remediation

Microcystin structures are exceedingly resistant to chemical breakdown, such as hydrolysis or oxidation. In addition, microcystin toxins are nonvolatile, hydrophilic, resistant to photodegradation, and are stable over a wide temperature and pH range. The structures are therefore extremely stable under most natural conditions. This makes remediation efforts to rid waters from contaminated microcystin toxins difficult and costly. Furthermore, due to the delicate nature of deceased algal cells that are prone to rupturing and contain microcystin, cleanups are usually extremely time intensive (International Organization for Standardization, 2005). The efficacy of drinking water filters to remove microcystin toxins varies significantly by filter type. A study in 2006 found that carbon filters allowed only 0.05-0.3% of the toxin load to pass through, while pleated paper and string based filters allowed more than 90% of the toxin load through (Pawlowicz et al., 2006).

Microcystin-producing cyanobacteria thrive in waters with warmer climate conditions. Because of this, harmful algal blooms (HABs) in western Lake Erie occur more commonly during hot summer months. With anthropogenic climate change, HAB occurrences are expected to increase along with rising temperatures in the northwestern Ohio region (Michalak et al., 2013).

Overview

With a combination of increased chemical fertilizer use and anthropogenic climate change, eutrophication will have an increasing impact on western Lake Erie's ecosystems, environment, and economies over the next few decades. In particular, algal blooms that produce microcystin toxins, as well as hypoxic water, degrade both ecosystem health and public health. These effects raise significant concerns for key stakeholders including citizens, policymakers, public health officials, and environmental advocates. The following sections of this paper will review those effects by analyzing the role HABs have on individual species; aquatic and terrestrial ecosystems; public health; as well as the economy and environment at-large. In addition to the effects eutrophication has on species, the environment, human health, and the economy; this paper will provide an overview of the benefits gained by using chemical fertilizers.

Ecological Effects

Large quantities of toxins produced by HABs affect the ecology of both marine and fresh water biomes. For example, 34 phytoplankton species are known causative agents in fish and shellfish mortality events along the U.S. west coast (Lewitus et al., 2012). This section will discuss the mechanisms by which organisms are directly and indirectly exposed to HAB toxins, as well as the impacts they incur as a result of increased algal growth.

Direct Exposure

Organisms are affected by HABs by way of either direct or indirect exposure. Direct exposure to microalgal cells and their toxins occurs through drinking or ingesting them through various consumption modes, such as filter feeding or predation. Smaller organisms such as zooplankton and shellfish often retain these toxins within their body cavities, and can present issues for bioaccumulation along the freshwater food chain. In calm, summer months, cyanobacteria forms a thick layer of surface scum that is dispersed over a significant portion of western Lake Erie. When wind and wave action is increased, however, this surface scum often concentrates closer towards shorelines. Wildlife and domestic animals that obtain their drinking water supplies from lake shorelines are therefore often directly exposed to large quantities of both algal cells and their toxins. Principal routes by which representative groups of organisms are directly exposed to harmful microalgal microcystin toxins includes the ingestion of cells by zooplankton, molluses, fish, birds, and terrestrial mammals (Landsberg, 2002).

In addition to obtaining direct exposure to microalgal microcystins through the ingestion of cells, organisms may also come into contact with extracellular microcystin toxins. These toxins have often been released from their cell membranes by way of either force or decomposition. If concentration levels are low with respect to water volume, then direct exposure to extracellular microcystin is unlikely. However, organisms that feed in the lake during the expiration of algal blooms are highly susceptible to coming into direct contact with extracellular microcystin. Furthermore, due to microcystin's highly stable amino acid structure, the toxins can persist in lake waters for months before being broken down by natural processes (Landsberg, 2002).

Indirect Exposure

Aside from direct exposure with HABs, organisms are also susceptible to indirect exposure with algae. When organisms consume other organisms that have previously been directly exposed to microcystin and other toxins, they transfer trophically through the food chain. Worse, toxicity concentration rates increase with each higher trophic level, due to bioaccumulation, bioconversion, and/or biomagnification. One of the most common cyanobacterium in western Lake Erie, Microcystis aeruginosa, is known to produce microcystin toxins that readily move through the food chain in this manner (Kotak et al., 1996).

Impacts from Toxins

Exposure of HAB toxins can lead to mass mortalities of aquatic organisms. Exposure to such toxins usually results in an immediate physiological, pathological, or behavioral change, depending on the species and concentration.

The following are examples of species that are affected by toxic cyanobacteria in freshwater lakes and reservoirs:

• Molluscs:
  • Anabaena circinali
    • Reduced overall feeding for Alathyria condola, species of mussel (Negri & Jones, 1995)
• Zooplankton:
  • Anabaena affinis
    • Reduced overall feeding for Ceriodaphnia dubia, species of water flea (Kirk & Gilbert, 1992)
    • Reduced fecundity for Daphnia galeata, species of planktonic crustacean (Gilbert, 1990)
    • Reduced fecundity for Daphnia magna, species of water flea (Gilbert, 1990)
    • Reduced fecundity and mortality for Daphnia pulex, species of water flea (Gilbert, 1990)
  • Anabaenan flos-aquae
    • Feeding inhibition for Daphnia hyalina, species of planktonic crustacean (De Mott, et al., 1991)
    • Reduced feeding for Daphnia parvula, species of planktonic crustacaen (Fulton, 1988)
    • Reduced feeding for Daphnia pulex, species of planktonic crustacaen (Fulton, 1988)
    • Feeding inhibition for Daphnia pulicaria, species of planktonic crustacean (De Mott, et al., 1991)
    • Feeding avoidance for Diaptomus reighardi, species of copopod (Fulton, 1988)
    • Feeding avoidance for Eurytemora affinis, species of copopod (Fulton, 1988)
  • Anabaena minutissima var. attenuate
    • Reduced feeding, survival, and inhibition of appendage beat rate for Daphnia carinata, species of planktonic crustacean (Peter & Lampert, 1989), (Forsyth et al., 1992)
  • Aphanizomenon flos-acquae
    • Reduced feeding and fecundicity for Acartia bifilosa, species of copepod (Sellner et al., 1994)
    • Inhibition of appendage beat rate for Daphnia carinata, species of planktonic crustacean (Haney et al., 1995)
    • Feeding avoidance for Diaptomus reighardi (Fulton, 1988)
    • Reduced feeding, increased avoidance, and reduced fecundity (Fulton, 1988), (Sellner et al., 1994)
  • Microcystis aeruginosa
    • Reduced feeding and fecundity for Acartia bifilosa (Sellner et al., 1994)
    • Reduced feeding for Bosmina longirostris, species of water flea (Fulton & Pearl, 1987), (Fulton & Paerl, 1989)
    • Reduced feeding for Ceriodaphnia quadrangula, species of planktonic crustacean (Fulton & Paerl, 1989)
    • Reduced feeding and mortality for Daphnia ambigua, species of planktonic crustacean (Fulton & Paerl, 1989)
    • Feeding inhibition for Daphnia hyalina (De Mott, et al., 1991)
    • Reduced growth and depressed clutch size for Daphnia longispina, species of planktonic crustacean (Stangenberg, 1968), (Reinikainan et al., 1994), (Hietala et al., 1995)
    • Feeding avoidance for Daphnia magna (Yasuno & Sugaya, 1991)
    • Mortality for Daphnia parvula (Fulton, 1988)
    • Reduced growth, depressed reproduction rate, and clutch size for Daphnia pulex (De Mott, et al., 1991), (Reinikainan et al., 1994) , (Hietala et al., 1995)
    • Feeding inhibition for Daphnia pulicaria (Lampert, 1981), (De Mott, et al., 1991)
    • Reduced feeding of Diaptomus reighardi (Fulton & Paerl, 1989)
    • Mortality for Eucypris virens, species of planktonic crustacean (Stangenberg, 1968)
    • Feeding avoidance and mortality for Moina macrocopa, species of water flea (Yasuno & Sugaya, 1991)
    • Mortality for Moina micrura, species of water flea (Fulton, 1988)
    • Reduced feeding for Simocephalus serratulus, species of crustacean (Fulton & Paerl, 1989)
  • Planktothrix agardhii
    • Reduced growth and fecundity for Daphnia pulicaria (Infante & Abella, 1985)
    • Reduced growth and fecundity for Daphnia thorata, species of planktonic crustacean (Infante & Abella, 1985)

In addition to the aforementioned species harmed by algal toxins, fish, reptiles, and mammals such as birds, are often affected as well. However, animals that drink contaminated freshwater are by far the largest terrestrial group affected by HABs.

Overall effects of HABs on food webs and ecosystems are often difficult to study. This is particularly due to the complexity of such food chain systems. The set of long-term implications of released algal toxins currently requires further investigation.

Impacts from Hypoxia

In addition to HAB toxins, algal blooms also produce hypoxic (low-oxygen) water over time. This is due to bacterial decomposition of algae that has grown from added nutrients (phosphorus and nitrogen from chemical fertilizers). Due to bacterial respiration during this process, temperature differences between poorly oxygenated water and oxygenated-water helps stratify water columns to prevent mixing from occurring.

Hypoxic water zones typically do not kill fish populations by way of suffocation (Almeida, 2015). Instead, by decreasing the amount and quality of habitat available, fish become physically constrained to habitable zones that do provide adequate oxygen, light, and temperature levels. However, with other species inhabiting these environments already, fierce competition between species often occurs.

During mid-late summer, water stratification becomes more intense, which prevents fish from occupying the cooler, poorly oxygenated bottom waters, where benthic prey are abundant.

Due to overall warmer temperatures year round, Lake Erie becomes more productive, and thereby allows the increase of amount of prey available and habitat suitability early in the year. However, these benefits don't cancel out the negative effects that occur during late summer.

Fish species that are most affected by hypoxic water zones in Lake Erie include the yellow perch (Perca flavescens), rainbow smelt (Osmerus mordax), emerald shiner (Notropis atherinoides), and the round goby (Neogobius melanostomus). These fish primarily feed on zooplankton and benthic organisms. Due to the decreased habitat availability during late summer months, zooplankton becomes the primary source of food for these fish during this time. However, the availability of zooplankton in warmer, upper waters becomes constrained over time. Furthermore, algal toxins directly affect many species of zooplankton, as cited previously. With decreased overall availability of zooplankton prey, significant populations of fish along the food chain become malnourished. These effects strongly increase the risk for mass death among aquatic species.Continued on Next Page »