Environmental Health Impacts of Excessive Cropland Fertilization

By Daniel G. Graetzer, Ph.D.
Faculty Member, School of Health Sciences, American Military University

Editor’s Note: This article is the second article in a three-part series on the history of enhancing global food security. Read part one.

The Haber-Bosch process detailed in part one of this series produced an estimated 150% of the food required to feed the world. As a result, the development of more and better fertilizers probably will no longer significantly improve current global food security. However, the continued application of technology to solve agricultural problems that often no longer require excessive technology-based solutions has the potential to create more problems than benefits.

Virtually unrestricted worldwide cropland fertilization using synthetic ammonium nitrate has greatly increased emission of nitrous oxide, a greenhouse gas with more than 300 times more heat-retaining capability than carbon dioxide. The miracle of making “bread from the air” becomes clouded when smaller factories without urea-making capacity vent toxic fumes into the atmosphere.

Carbon Dioxide Emissions from Fertilizers Comprise Less than 10 Percent of Global Carbon Dioxide Release

Carbon dioxide emissions from fertilizers remain a primary concern and currently comprise less than 10% of global carbon dioxide release. But discharges of sulfur oxides and hydrogen sulfide — even when isolation and removal scrubbers and strippers are used — continue to pollute air and water. Excess nitrogen-related compounds pollute groundwater and soil, creating storm water runoff that is potentially harmful to humans, plants, fish, marine animals, and birds.

Nitrous oxide emissions worsen global warming and diminish air quality by blunting “beneficial” stratospheric ozone, which protects against ultraviolet radiation damage. At the same time, nitrous oxide emissions fuel “harmful” ground-level ozone, the principal component in smog. Continued unrestricted industrial use of natural gas as the source of nitrogen and energy for nitrogen fixation raises serious environmental concerns because geologic extraction of natural gas greatly contributes to carbon dioxide emissions as well as soil and water contamination.

The misuse of ammonia fertilizer spurs surface water eutrophication (excessive richness of nutrients in a lake or other body of water) as nitrates soak deep into the soil following irrigation and rainstorms, running downhill to over-fertilize and contaminate downstream groundwater and wells.

Food crops on estimated average take up only about 40% of the synthetic nutrients applied each growing season; the remainder pollutes water and air, and contributes to algae blooms in lakes, rivers, and oceans. Soil imbalances due to acidification by excess nitrogen via storm water runoff also deplete important minerals such as calcium, phosphorus, and magnesium. Applying appropriately timed and restricted synthetic fertilizer not only reduces cost, but can more efficiently improve soil health compared to the uncontrolled nitrogen release by manure used in many less developed countries.

[View an image of the surface water eutrophication caused by runoff of excess cropland fertilizer.]

Root burn is common in areas of nitrogen environmental abuse, with some plant roots exhibiting high sensitivity to nonorganic urea prevalent in lower-quality fertilizers. In higher-quality fertilizers, excess soluble salts can potentially burn roots and foliage, stunt plant growth, wilt flowers, and inhibit water delivery within plants.

Pest control becomes increasingly necessary with over-fertilization as lush leaves attract more insects during both normal and abnormal times of the year. Aphids and other nuisance pests thrive with increased foliage vigor, as do weeds and fungus-associated brown patches in turf grasses.

Excessive ammonia fertilizer production and use — relatively cheap and available as more manufacturers enter the marketplace, and insufficient education regarding the complex dangers of over-fertilization — aggravate already serious problems for the environment. Developing educational materials that farmers in less developed countries can easily understand is particularly important because the negative effects of excessive fertilization are often not immediate or obvious.

The Need to Highlight the Necessity of Applying Only Enough Fertilizer and Only at Appropriate Times

Agricultural management and legislation need to highlight the necessity of applying only enough fertilizer and only at appropriate times that specific crops can use effectively; this is similar in concept to the prudency of only prescribing the lowest dose of antibiotics for the shortest length of time to avoid creating future drug-resistant bacterial strains.

Farmers and gardeners have often underestimated — and therefore increased — the risk of acute and chronic health problems related to liver and urinary dysfunction; for example, non-Hodgkin’s lymphoma potentially linked to excessive direct and/or indirect agricultural chemical exposure. Children living in areas of heavy fertilizer and pesticide use have an increased risk of leukemia, with pets and other animals also at increased risk for several forms of cancer.

Pollution of groundwater and soil via surplus nitrogenous compounds create potentially toxic runoff for humans, plants, fish, marine animals, and birds. Conventional agriculture backlash against greenhouse gas emissions, toxic chemical release, and other environmental abuses helped stimulate the modern “organic movement.”

Human respiratory ailments are common in areas that violate EPA standards for “criteria” pollutants such as ozone, nitrogen oxide, and smog-born particulates. Methemoglobinemia, commonly called “blue baby syndrome,” caused by ingestion of excessive nitrogen in water affects infants under one year of age and the elderly. The result may be gastrointestinal swelling, diarrhea, and inhibited protein digestion. Mixing nitrates with iron in red blood cells hampers oxygen transport. Because ingested nitrogen remains tasteless, odorless, and colorless, only specific testing can identify the risk.

Disproportionate application of technology can potentially cause more harm than good, particularly if farmers in less developed countries remain poorly educated about the many serious complex problems of over-fertilization.

Suggestions to alleviate environmental problems related to excessive ammonia-based fertilizer production and use include:

1. Increase public and commercial agricultural awareness by developing, promoting, and subsidizing sustainable environmentally friendly fertilization methods and distributing related educational materials, particularly in less developed countries.
2. Calculate “crop nitrogen balance” based on irrigation and needs of soil and plants, while requiring detailed fertilization plans and regular soil testing at all agricultural levels.
3. Limit fertilizer use in water extraction and nature protection areas, especially following regular irrigation and excessive rainfall, and implement erosion control procedures that complement topographic and soil conditions.
4. Review pest, weed, animal and aquatic life disease control measures, especially in high-risk areas.
5. Monitor specific human health concerns as related to certain agricultural areas.
6. Delay ploughing of straw, roots and leaves into the soil.
7. Prevent nitrogen leaching after growing seasons by increasing autumn/winter green cover.
8. Apply fertilizer only at necessary times; educate farmers regarding seasonal differences for various crops; and calculate how rapidly nitrogen dissipates within soil in different environments at distinct times of the year.
9. Investigate other methods to produce ammonia and urea which use less natural gas, and accumulate and release less pollutants.
10. Monitor, reform, and enforce management and legislation regarding global production and use of ammonium nitrate, and related environmental and economic concerns.

About the Author

Daniel G. Graetzer, Ph.D., received his B.S. from Colorado State University/Fort Collins, MA from the University of North Carolina/Chapel Hill, and Ph.D. from the University of Utah/Salt Lake City and has been a faculty member in American Military University’s School of Health Sciences, Department of Sports and Health Sciences, since 2015. As a regular columnist in encyclopedias and popular magazines, Dr. Graetzer greatly enjoys helping bridge communication gaps between recent breakthroughs in biomedical knowledge, practical application of developing scientific theories, and societal well-being. Dr. Graetzer has obtained AMU funding to research the productive versus destructive uses of modern science as related to the development, production, and deployment of chemical, biological, and nuclear weapons. Dr. Graetzer looks forward to collaborating with AMU military students to further investigate the numerous physical and mental stressors experienced by tactical athletes within variety of combat environments.