Iowa primed for potentially 'epic' increase in stream pollution
A buildup of nitrate in farm fields that has likely resulted from Iowa’s longest-running drought in 70 years has set the stage for a potentially massive uptick in stream pollution, state water-quality observers say.
Nitrate Buildup Threatens Stream Pollution
Iowa's prolonged drought, which has lasted for over three years, has led to an accumulation of nitrate in farm fields. When unused nitrogen fertilizer is not absorbed by crops during drought years, it can be quickly flushed into streams by heavy spring rains. This phenomenon can result in a substantial increase in stream pollution.
Chris Jones, a former University of Iowa researcher who studies agriculture's effects on water quality, warns that these extreme events are becoming more frequent and will have significant consequences when the wet regime returns. He describes the potential increase in stream pollution as 'epic'.
Records show that in 2013, when Iowa experienced heavy spring rainfall after a severe drought, the nitrate levels in streams increased by more than 400% compared to the previous year. The amount of nitrate in streams continued to rise until 2016, and climate predictions indicate that the upcoming spring may be warmer and wetter than usual.
Environmental Threats of Nitrate Pollution
Nitrogen fertilizer is essential for maximizing crop yields in Iowa's corn fields. However, excessive nitrogen can have negative environmental impacts. Drinking water in major cities, such as the Des Moines metro area, relies on rivers as a significant water source. Nitrate contamination in these rivers often requires costly removal processes to ensure the safety of the water.
Elevated levels of nitrate and phosphorus, another prominent nutrient, can also cause ecological issues. Algae blooms in streams and rivers result from excessive nutrients, leading to oxygen depletion and the release of toxins harmful to aquatic life and recreational swimmers. These crop fertilizers are major contributors to the Gulf of Mexico's dead zone.
Iowa's extensive network of underground tiling further expedites the release of nitrate into streams. While these perforated pipes help drain water from fields and improve crop production, they also provide a quicker pathway for nitrate to enter waterways. Approximately half of Iowa's cropland is drained by tile, and despite recent efforts to reduce tiling, farmers continue to install more.
Uncertain Future and the Need for Sustainable Solutions
In recent years, efforts have been made to implement edge-of-field conservation practices to slow the release of surface runoff and remove nutrients before they reach streams. However, the overall impact of these measures on water quality in Iowa is still unclear.
State funding cuts to the nutrient research center and uncertainties surrounding data collection hinder the analysis of long-term trends in stream pollution. While there has been a decline in overall stream pollution in recent years, the ongoing drought makes it challenging to determine the direction of the situation. Opinions on progress differ, with some pointing to the effectiveness of conservation practices and others highlighting the need for stricter regulations and diversification of crops.
Ultimately, sustainable solutions that address the causes of nitrate pollution will be crucial for improving water quality in Iowa. These solutions may involve reducing reliance on corn and soybeans, which require significant nitrogen fertilizers, and exploring alternative crops that are less demanding on the environment.
