How Pollutants Affect Farming In The American Midwest

Agriculture is the leading source of impairments in the United States' rivers and lakes. The pollutants from farming include sediments, nutrients, pathogens, pesticides, metals, and salts. In the Midwestern US, the Corn Belt region's intensive agriculture activities alter the water quality and physical habitat of small streams. The pollutants in this region include pesticides, nutrients, sedimentation, and riparian disturbance. The leading pollutant in rivers and streams across the US and the world is sediment, which can overwhelm aquatic ecosystems, smother breeding areas, and degrade coastal and marine ecosystems.

Pesticides and fertilizers

Agricultural activities, such as the application of pesticides and fertilizers, can alter the natural flow of water and the health of stream ecosystems. These chemicals do not remain stationary; instead, they are transported into local streams, rivers, and groundwater through runoff, infiltration, and irrigation return flows. This process is influenced by factors such as rainfall, snowmelt, cattle loafing in stream corridors, and stream channel erosion.

The consequences of this pollutant transport are evident in the stimulation of algal blooms in lakes and rivers. Increased levels of nitrogen and phosphorus from fertilizers and manure contribute to the development of hypoxic (low oxygen) conditions, detrimental to aquatic life. Additionally, the presence of pesticides in these water sources poses risks to aquatic organisms and fish-eating wildlife, potentially impacting the food web and drinking water supplies.

The impact of pesticides and fertilizers on water quality is not limited to the aquatic environment. Groundwater, including drinking water sources, can also be affected by these contaminants. More than 13 million US households rely on private wells for their water supply, making the potential human health impacts of pesticide and fertilizer pollution a significant concern.

To address these issues, farmers can adopt soil and water conservation practices. Nutrient management practices, such as targeted fertilizer and manure application through soil testing and crop-specific calibration, can help minimize runoff. Additionally, using drip irrigation instead of furrow irrigation allows for better control of pesticide and nutrient levels in irrigation water. By implementing these practices, farmers can reduce the environmental and health impacts of pesticide and fertilizer pollution.

Manure and methane emissions

Agriculture is a major economic driver in the Midwest, and intensive farming practices are common. These practices, however, can have detrimental effects on the environment, particularly water quality. Manure, a byproduct of livestock operations, is a significant source of pollution. When manure is not properly managed, it can contaminate local water sources through runoff and infiltration. This leads to increased nutrient levels, specifically nitrogen and phosphorus, in lakes and rivers, stimulating the growth of algal blooms. The consequence of these blooms is the development of hypoxic conditions, which are low in oxygen and harmful to aquatic life.

Methane emissions from manure further exacerbate the problem. Methane is a potent greenhouse gas, with a global warming potential 28 times that of carbon dioxide over a 100-year period. According to the EPA, manure methane emissions in the United States have been increasing at an average rate of 0.03 million metric tons per year from 1990 to 2020. This is particularly concerning as methane emissions from manure have been found to contribute more to climate warming than enteric methane emissions from livestock.

To address these issues, farmers can adopt better manure management practices. For example, storing livestock manure in lagoons, covered stockpiles, or protected upland areas can minimize runoff risks. Additionally, switching to practices that handle manure in drier, aerobic conditions can help reduce methane emissions. By implementing these and other conservation practices, farmers can play a crucial role in mitigating climate change and improving water quality in the Midwestern United States.

It is worth noting that the Midwest is a top contributor to the United States' cumulative greenhouse gas emissions. This is due in part to the region's agricultural practices, but also to its urban areas, where natural gas and propane use in buildings and homes can account for a significant portion of GHG emissions.

Soil erosion and sedimentation

Agricultural activities, such as the application of fertilizers and pesticides, as well as land conversion for farming, have altered the natural flow of water and increased the transport of contaminants into local water bodies. This has resulted in increased sedimentation rates, with sediment being one of the leading pollutants in rivers and streams across the United States. Excessive sedimentation can overwhelm aquatic ecosystems, smother breeding areas, and degrade coastal and marine ecosystems, including coral reefs.

Soil erosion, specifically in the Midwest, has been a subject of various studies. Some research has indicated that rates of soil erosion have decreased over time, with subdecadal estimates showing a 34% reduction from 1982 to 2015. However, other data, such as sedimentation records from Iowa lakes, suggest that most sediment accumulation has occurred since 1950, coinciding with the intensification of agricultural practices. This discrepancy in trends highlights the complexity of soil erosion dynamics and the need for comprehensive assessments.

Climate change is also expected to influence soil erosion rates in the region. Studies have predicted that certain adaptations in crop management, such as shifts from maize and wheat to soybeans, will likely occur due to economic and environmental factors. These changes in crop rotations can further impact erosion rates, with simulations showing significant increases in runoff and soil loss for the latter half of the 21st century compared to the late 20th century. Additionally, climate change-induced variations in temperature and precipitation patterns can exacerbate soil erosion and sedimentation issues in the Midwest.

To address the challenges posed by soil erosion and sedimentation, farmers in the Midwest can adopt soil and water conservation practices. These practices aim to minimize the runoff of sediments, nutrients, and other pollutants. For example, implementing drip irrigation instead of furrow irrigation can reduce water loss and provide better control over the addition of pesticides and nutrients. Additionally, nutrient management practices, such as targeted fertilizer application and manure storage methods, can help minimize nutrient runoff and reduce the impact on water quality.

Water quality and pollution

Agricultural contaminants, such as those from fertilizers and pesticides, can impair the quality of surface water and groundwater. These contaminants can enter water sources through runoff, infiltration, and irrigation return flows, ultimately affecting local streams, rivers, and groundwater. The Midwest is particularly vulnerable to these issues due to its heavy reliance on agriculture.

Fertilizers and pesticides are routinely used in agriculture to enhance crop yields, but they can have detrimental effects on water quality. Excessive use or improper management of these chemicals can lead to runoff, contaminating nearby water bodies. This is a pressing issue in the Midwest, where nearly 1.2 billion acres of farmland produce a significant portion of the nation's food supply.

Sedimentation is another leading pollutant in rivers and streams across the Midwest and the world. Soil erosion, often exacerbated by agricultural practices, contributes to the increase in sediments in water bodies. This can have various adverse effects, including reduced transport capacity, limited light penetration, and interference with the feeding habits of aquatic life.

Climate change also poses risks to Midwest agriculture, with the potential for more extreme temperatures, variable precipitation, heat waves, and frequent droughts. These shifts in climate patterns can impact water quality and availability, further exacerbating the challenges of agricultural pollution in the region.

To address these issues, there is a growing emphasis on implementing conservation practices and adopting sustainable agricultural methods. This includes improving nutrient management, adopting regenerative agriculture strategies, and exploring organic farming practices. By prioritizing these initiatives, the Midwest can strive to balance its agricultural productivity with the preservation of its vital water resources.

Climate change and extreme weather

Climate change poses a significant challenge to the Midwest, with the region already experiencing more frequent and intense heat waves, higher temperatures, and more variable precipitation. These changes have direct implications for agriculture, which is a vital sector in the Midwest, contributing significantly to the region's economy and the nation's food supply.

The Midwest's highly energy-intensive economy, with per capita emissions of greenhouse gases, further exacerbates the problem. The region has the potential to reduce these emissions, but it is currently falling short. As a result, the Midwest is subject to a wide range of temperature and precipitation extremes, with cold air masses from the north and warm, humid air from the Gulf of Mexico.

The agricultural lands of the Midwest are particularly vulnerable to climate change and extreme weather. In the short term, some benefits may occur, such as longer growing seasons and increased yields for certain crops due to rising carbon dioxide levels. However, these advantages are expected to be temporary and progressively offset by extreme weather events. Higher temperatures and more variable precipitation could have significant negative consequences for Midwest agriculture, including reduced yields and crop failures. Wheat yields may increase, but corn and soybean yields are projected to decline due to the shortening of the reproductive development period.

Extreme weather events, such as heat waves, droughts, and intense storms, will have a detrimental impact on agricultural productivity. For example, high temperatures during the early spring can decimate fruit crops by causing premature plant budding, making flowers vulnerable to subsequent cold snaps. Additionally, climate change can alter pest and disease prevalence, leading to more severe outbreaks and further impacting crop production.

Water quality is also at risk due to extreme weather. Increased rainfall and flooding can cause erosion, reducing water quality and negatively impacting aquatic ecosystems. Warmer temperatures contribute to the growth of toxic algae, further degrading water quality and harming fish habitats. These changes threaten the Midwest's drinking water sources, such as the Great Lakes, which provide drinking water to over 40 million people.

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