October 30, 2011
Overuse and Abuse of Nitrogen Fertilizers in California Agricultural Lands
Without the use of nitrogen fertilizer, California agricultural lands could risk not reaching its optimum yield. As a consequence, food production companies would lose a certain amount of profit and consumer demands could possibly not be reached. Often times as nitrogen passes through plants and soil in a repetitive cycle the loss of nitrogen is greater than the benefit and as a result, the plant growth is no longer as significant. This ultimately puts a limit on crop production rate. However, scientists have come up with farming techniques that have revolutionized agriculture. Nitrogen fertilizer is one of those inventions and is a product of the Haber-Bosch process. This fertilizer has ‘allowed agricultural production to keep pace with world population growth,’ according to the International Fertilizer Industry Association.
Nitrogen fertilizers have many effects on the Nitrogen cycle that can lead to negative anthropogenic effects as well as environmental. There are several disruptions in the natural cycle of Nitrogen that can occur.
First of all, artificial nutrients dumped into soil can result in a loss of its capacity to hold nutrients (Lowe, pg.10). It is estimated that plants have no use for up to 50% of the chemical fertilizers placed on them.
Agricultural regions of the Southwest are composed of mainly shallow, coarse-textured and therefore highly permeable soils and aquifers. It is common for these areas to be vulnerable to nitrate contamination (Harter pg.3).
Nitrates are the most readily formed and available use of Nitrogen, and they are extremely soluble. It is easily carried through the soil with water to be taken up by plants. If the land is irrigated, there is a chance nitrate can move past the plant roots and into the groundwater or other agricultural tile drainage or surface waters (Mosier, pg.13). In major agricultural areas such as the Imperial, Central, Salinas, and other coastal valleys in California, there is groundwater nitrate contamination (Harter pg.3). When nitrate levels exceed those of the EPA’s Maximum Containment level set at 10mg/l, certain health risks occur. One of these being methemoglobinemia (infants especially are vulnerable).
In addition, when converting ammonium into nitrate, nitrite will naturally occur. Nitrite is similar to nitrate in its movement through the soil and possibility of contaminating groundwater (Reid para.7).
Ammonia volatilization also contributes to nitrogen losses. Ammonia volatilization occurs in areas where the soil is warm, dry, and too much of a nitrogen fertilizer is applied (Buchholz). There is a concern with concentrations becoming toxic. This can happen when too many of these tiny particulates enter a confined area. Ultimately, one of the biggest concerns is reducing air quality (Reid, pg. 11).
Moreover, the effects that Ammonia and nitrate can have on biodiversity can be disastrous. Eutrophication that can lead to algal blooms and a die-off of fish species are a concern from Nitrogen fertilizer use such as ammonia emissions that can deposit on bodies of water and nitrate leached from the soil (Mosier pg.17). Ultimately, the impacts this is having can decrease fish populations resulting in less available resources for people to consume.
Lastly, the process of denitrification can transform the nitrogen fertilizer into nitrous oxide. This is a greenhouse gas, which has approximately three hundred times more impact than carbon dioxide on climate change (Lowe, pg.10). The effects of using these nitrogen fertilizers may not be shown right away as can be seen from eutrophication, but the long-term impacts may be detrimental.
If California continues with overusing and abusing its Nitrogen fertilizer use, it makes itself susceptible to the outcomes seen in China’s croplands. The soil became more acidic so that it was unproductive, and in addition to water contamination, China experienced increases in greenhouse gas emissions. All of these disastrous consequences were negligent monitoring of nitrogen fertilizers.
China’s overuse of nitrogen fertilizers has forced the government to take action against the pollution. One of their solutions is a five-year plan, which calls for a reduction in carbon intensity by implementing new domestic laws that legally require companies to meet emission reduction targets.
Although California may not have a government plan to target the nitrogen pollution, there are other ways in which farmers, themselves can become proactive in reducing the pollution. Some example solutions include securing stored manure in order to prevent runoff or enforcing livestock feed rations that are not above the necessary.
Another solution is to completely phase out chemical fertilizers and instead use organic fertilizers. According to the Third World Network’s report, “Avoiding Nitrogen fertilizer over-use is a “multiple win”: farmers save money, there is less water pollution, smaller greenhouse gas emissions, and a smaller acidification burden on soil and water.”
Image Source:
Harter, Thomas. “Agricultural Impacts on Groundwater Nitrate.” Nitrates in Groundwater. University of California, Davis, July-Aug. 2009. Web. 10 Oct. 2011. <http://www.swhydro.arizona.edu/archive/V8_N4/feature2.pdf>.
Citations:
Mosier, Arvin, John K. Syers, and J. R. Freney. Agriculture and the Nitrogen Cycle: Assessing the Impacts of Fertilizer Use on Food Production and the Environment. Washington, D.C.: Island, 2004. Print.
Lowe, Marcy, and Gary Gereffi. “A Value Chain Analysis of Selected California Crops.” Center on Globalization. Duke University, 04 July 2008. Web. 10 Oct. 2011. <http://www.cggc.duke.edu/environment/valuechainanalysis/CGGC_CACropsReport_7-4-08.pdf>.
Reid, Keith, Kevin McMcKague, and Hugh Simpson. “Environmental Impacts of Nitrogen Use in Agriculture.” Ontario Ministry of Agriculture, Food and Rural Affairs / Ministère De L’Agriculture, De L’Alimentation Et Des Affaires Rurales. Web. 10 Oct. 2011. <http://www.omafra.gov.on.ca/english/engineer/facts/05-073.htm>.
Harter, Thomas. “Agricultural Impacts on Groundwater Nitrate.” Nitrates in Groundwater. University of California, Davis, July-Aug. 2009. Web. 10 Oct. 2011. <http://www.swhydro.arizona.edu/archive/V8_N4/feature2.pdf>.
Buchholz, Killpack. “WQ257 Nitrogen in the Environment: Ammonia Volatilization | University of Missouri Extension.” University of Missouri Extension Home. Department of Agronomy. Web. 10 Oct. 2011. <http://extension.missouri.edu/p/WQ257>.
About the authors: Ticia Lee and Wendy Whitcombe are working towards their bachelor degrees in the USC Environmental Studies Program.
October 10, 2011
Fertilizer in the Water: How to Mitigate Widespread Pollution
Fertilizer is a vital component of both modern and ancient agriculture, its benefits ranging from increased soil health to increased agricultural productivity. Unfortunately because of its high nutrient content, which includes nitrogen and phosphorus, fertilizer can negatively affect water quality. Although nitrogen and phosphorous are both vital nutrient components of soil that promote soil health and plant growth, they can have drastic polluting effects when they are leached out of soil and carried off by water. The EPA cites agricultural runoff as the leading source of impairment to surveyed rivers and lakes. Because it is considered a nonpoint source (link to: http://water.epa.gov/polwaste/nps/whatis.cfm) of water pollution, managing agricultural runoff is one of the greatest challenges posed to water quality.
The effects of agricultural runoff on water quality varies from nitrate pollution in groundwater as it percolates down from soils, to eutrophication of freshwater and coastal ecosystems, which greatly threatens both biodiversity and ecosystem services. Eutrophication is rated by the EPA as “the most widespread water quality problem in the United States” (Plaster 339). Algal blooms resulting from nutrient abundance (of phosphorous in freshwater ecosystems and nitrogen in coastal ecosystems) can greatly affect the entire food web in a given ecosystem, as their decomposition consumes the dissolved oxygen in the water and creates a hypoxic zone. Once the water is hypoxic, there is not enough dissolved oxygen to sustain most forms of life. The ecosystem is further altered and biodiversity is further threatened as turbidity increases (due to the dead matter from the algal blooms clouding the water). Areas like this in the United States and around the world are known as dead zones.
A dramatic example of one such dead zone is the Gulf of Mexico hypoxic zone, which was caused in a large part by agricultural runoff is in the Mississippi River watershed. The USGS describes the Gulf of Mexico Dead Zone as “an area of approximately 6,000-7,000 square miles of water with oxygen levels below 2 parts per million.” Nutrient-enriched waters, resulting from runoff in the Mississippi River Delta, made their way into the Gulf of Mexico and caused the subsequent eutrophication which is responsible for the area’s current hypoxic state. Now these areas of the Gulf of Mexico support fewer organisms, which poses a threat to both biodiversity and local fisheries.
Though the challenges of managing pollution from agricultural runoff are numerous and complicated, by following a series of Best Management Practices individuals and the agriculture industry can limit their impact on the environment, while still maintaining healthy and productive soils (Plaster 342). Practices such as conservation tillage, efficient irrigation, proper management of livestock and their manure, and many other sustainable agricultural practices can help reduce agricultural runoff. Also, improving fertilization practices and applications can reduce excess fertilizer and thus nutrient pollution from agricultural runoff.
In addition to changing our agricultural practices, there are other methods that can stem fertilizer runoff into watersheds. For example, a recent study reported by Science Daily found that water quality increased after lawn fertilizers were banned. Furthermore, in an attempt to mitigate problems like the hypoxia in the Gulf of Mexico, the USGS is currently exploring how the restoration of wetlands and other natural ecosystems could help filter nutrients out of runoff before it reaches streams or coastal waters. Though many of these problems may seem daunting, awareness of the issues and education of the public in Best Management Practices can help reduce water pollution and maintain the vitality of both freshwater and costal ecosystems for future generations.
Cited: Plaster, Edward J. Soil Science and Management. 5th edition. New York: Delmar-Cengage, 2009.
About the authors: Vivian Breckenridge and Julia Mangione are working towards their bachelor degrees in the USC Dornsife College of Letters, Arts and Sciences.