Modern Agriculture’s Impact on Nutrient Loading

Overview

Modern agricultural practices are very effective at producing high crop yields and increasing overall food security. However, many of these practices have significant environmental externalities that affect human welfare in various ways. Our Healthy Soils for Healthy Waters Initiative focuses on nutrient loading, a widespread and destructive byproduct of intensive modern agriculture.

Eutrophication

Satellite image of 2011 bloom, the worst bloom in recent years, which impacted over half of the lake shore. (Credit: MERIS/ESA, processed by NOAA/NOS/NCCOS)

Satellite image of 2011 bloom, the worst bloom in recent years, which impacted over half of the lake shore. (Credit: MERIS/ESA, processed by NOAA/NOS/NCCOS)

Nitrogen and phosphorus are important nutrients for plant growth and farmers commonly add them to soil to increase crop productivity. Rain easily washes away some of these added nutrients and in the case of the Mississippi River basin, eventually collects in the Mississippi River and flows to the Gulf of Mexico. This warm, nutrient-dense freshwater from the river floats above the cooler, saline water of the Gulf.  The extra nutrients, usually a limiting factor in algal growth, enable excessive phytoplankton growth in the top layer of water. The plankton die and eventually sink to the bottom layer of the gulf, where they decompose and use up the oxygen in the bottom saline layer. Marine life needs oxygen to survive just like we do, so those organisms that are unable to move away from the oxygen-depleted “hypoxic” zone, such as lobsters, crabs, and young fish, die. With the current unstable state of nearly all fish stocks, these die-offs from hypoxic zones are making an already precarious situation even worse. In 2014, the hypoxic zone in the Gulf of Mexico measured in at 5,052 square miles. The zone fluctuates in size from year to year, but this is due to varying weather patterns, not any real overall reduction in pollution (Maryland DNR, 2005).

See the Greenleaf Advisors article: “New Research Identifies Tool to Mitigate Phosphorus

Harmful Algae

The algae that grows as a result of the eutrophication of the waters, or nutrient enrichment, is often directly harmful as well. Toledo is continually experiencing serious issues with water toxicity from their only water source, Lake Erie, which is being contaminated with nutrient runoff mostly as a result of agricultural practices (Seewer, 2014). In fall of 2014, the Lake Erie water was so polluted with the algae that it couldn’t be safely treated at the water treatment plant, and as a result, the 500,000 people the plant served had their water shut off (Frankel, 2014). The federal government has already given 17.5 million dollars to Toledo to educate farmers about best-management practices, such as cover crops (Frankel, 2014).

See the Greenleaf Advisors article: “Using an Ancient Approach to Farming to Address Lake Erie’s Modern Problems

HSHW Initiative

Greenleaf Communities’ Healthy Soils for Healthy Waters initiative aims to address the dire need for an effective and economical solution to eutrophication. In 2011, John Andersen Jr., former Great Lakes Director of The Nature Conservancy, established Greenleaf Communities as a nonprofit 501(c)(3) organization. Greenleaf Communities is currently overseeing field-scale research into farm management practices that significantly reduce the amount of phosphorus lost from the farm fields into waterways.

 

Sources

Seewer, J. (2014, May 9). Ohio asks neighboring states to help fight Lake Erie’s algae. Retrieved June 8, 2015.

Frankel, T. (2014, August 11). The toxin that shut off Toledo’s water? The feds don’t make you test for it. Retrieved June 8, 2015.

Maryland Department of Natural Resources. (2005, April 26). Coastal Bays, Nutrient Loading. Retrieved June 19, 2015, from http://www.dnr.state.md.us/coastalbays/water_quality/nutrient_load.html