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Why is agriculture important?

Agricultural land covers close to one-quarter of the Chesapeake Bay watershed. According to 2010 estimates from the U.S. Environmental Protection Agency (EPA), there are more than 87,000 farm operations and 8.5 million acres of cropland here. Farms in the Bay watershed produce more than 50 commodities, including corn, soybeans, wheat, fruits and vegetables. Agriculture is essential to all people: farms provide us with food and fiber, natural areas, and aesthetic and environmental benefits.

How does agriculture affect the Chesapeake Bay?

Agriculture is the single largest source of nutrient and sediment pollution entering the Chesapeake Bay. According to 2012 estimates from the Bay Program, agriculture contributes 42 percent of the nitrogen, 58 percent of the phosphorous and 58 percent of the sediment entering the Bay. Unfortunately, some agricultural practices—including over-irrigating farmland, over-tilling soil and over-applying fertilizers and pesticides—can push pollution into the Bay and its local waterways.

But well-managed agricultural lands can offer the Bay watershed a number of benefits and services, including sustained crop yields, restored rivers and streams, and valuable insect, bird and animal habitat. When effective agricultural land cover occurs year-round, these systems can store carbon, minimize soil erosion and reduce the watershed’s vulnerability to flooding and the effects of climate change.

Irrigation

Irrigation brings water to land. Through the use of hoses, sprinklers or other watering methods, irrigation can ensure consistent crop production in a range of weather conditions. Fruits, vegetables, grains and horticultural plants are the most commonly irrigated crops in the Bay watershed.

Poor irrigation practices, including the over-watering of crops, can promote erosion and push pollution into rivers and streams:

• Excess water that is not absorbed into the soil can wash into local waterways, carrying with it soil and sediment, fertilizers and pesticides, and nutrient-rich animal manure.
• Excess water that soaks into the soil can push nutrients into groundwater supplies, where it can remain for decades.

Tilling Soil

To prepare a field for planting, a number of farmers practice “conventional tillage,” turning the earth over with a plow. While tillage can loosen the soil and promote crop growth, it can also damage soil structure:

• Heavy machines can compact the soil that plow blades cannot reach, compressing the earth and making it difficult for rainfall to trickle into groundwater supplies.
• Loosened surface soil is prone to erosion; when irrigation and precipitation push sediment into rivers and streams, it can cloud the water and limit the amount of sunlight that can reach underwater plants.

Livestock Manure and Poultry Litter

Livestock manure and poultry litter are often applied to cropland as a form of fertilizer, providing crops with the nutrients needed to grow. But when more manure is applied to the land than a crop can absorb, or when large amounts of manure are improperly stored, the nutrients and bacteria that manure contains can:

• Be carried by runoff into rivers and streams
• Seep into groundwater supplies

According to 2010 estimates from the EPA, manure accounts for 19 percent of the nitrogen and 26 percent of the phosphorous entering the Bay. These excess nutrients can fuel the growth of algae blooms that block sunlight from reaching underwater grasses and, during decomposition, rob the water of oxygen that plants and animals need to survive.

Chemical Fertilizers

Like manure, chemical fertilizers can provide crops with the nutrients needed to grow. But when more fertilizer is applied to the land than a crop can absorb, these nutrients can:

• Be carried by runoff into rivers and streams
• Seep into groundwater supplies

According to 2010 estimates from the EPA, chemical fertilizers account for 17 percent of the nitrogen and 19 percent of the phosphorous entering the Bay. These excess nutrients can fuel the growth of algae blooms that block sunlight from reaching underwater grasses and, during decomposition, rob the water of oxygen that plants and animals need to survive.

Pesticides

Chemical pesticides can protect crops from weeds and insects. Some pesticides target just one or a few species, while others are considered “broad-spectrum” and target a group of similar species. Like livestock manure and chemical fertilizers, when pesticides are applied in excess, they can:

• Be carried by runoff into rivers and streams
• Seep into groundwater supplies

According to a 2012 report from the EPA, U.S. Geological Survey (USGS) and U.S. Fish and Wildlife Service, pesticides are frequently present in our streams and groundwater. While pesticide concentrations in local waterways are seldom high enough to harm human health, pesticide concentrations in a number of streams can impact aquatic and fish-eating wildlife. Scientific studies have discovered potential links between pesticide exposure and:

• The suppression of behavioral and immune systems in fish
• The development of intersex conditions in fish
• The impaired reproduction of fish-eating birds

How is the Chesapeake Bay Program working to reduce pollution related to agriculture?

Bay Program partners are working with farmers across the watershed to curb agricultural runoff. Conservation practices—often called “best management practices” or “BMPs”—can be implemented on area farms, and watershed states are counting on the expanded use of these practices to help them meet the goals set forth in the Chesapeake Bay “pollution diet,” or Total Maximum Daily Load (TMDL).

What are some common best management practices?

Best management practices are tools that farmers can use to reduce agricultural runoff into rivers, streams and the Chesapeake Bay. These tools can reduce a farm’s operational costs and improve a farm’s production. Some best management practices are voluntary or incentive-based, while others—like nutrient management planning for all agricultural operations in Maryland—are mandatory.

From the Field: Sustainable Agriculture in Lancaster County, Pennsylvania from Chesapeake Bay Program on Vimeo.

Conservation Tillage

Conservation tillage leaves one-third or more of a farm field covered with crop residue or vegetation throughout the year. When tillage is reduced and soil is left undisturbed, a field is less prone to erosion. Continuous no-till and minimum-till farming are two forms of conservation tillage.

Cover Crops

Cover crops are grown to provide soil cover and prevent erosion. Cover crops can be annual, biennial or perennial plants grown in a single or mixed stand during all or part of the year, including the non-growing season. Common cover crops include legumes (like cowpeas or clover), forage radish and cereal grains (like wheat, rye or barley).

Planting cover crops uses living plants to fill in bare soil in a field. This can occur when a main crop has been harvested, when there is a niche in a season’s crop rotation or when there is a need to interplant a cover crop with a cash crop. Cover crops can:

 

• Provide ground cover
• Reduce erosion
• Suppress weeds
• Reduce insect pests and diseases
• Absorb excess fertilizer and reduce nutrient leaching after a main crop is harvested
• Enrich soil with organic matter

Forest Buffers and Streamside Fencing

Grasses, trees and shrubs planted along the edges of farm fields and along rivers and streams can reduce the amount of pollutants flowing from the land into local waterways. These “buffers” can slow and absorb polluted runoff, stabilize stream banks, curb erosion and serve as habitat for wildlife.

Streamside fences exclude livestock from local waterways. Livestock exclusion fencing can reduce the amount of nutrients and pathogens entering the water, prevent stream bank damage and erosion, and improve animal health. Fences can be woven wire or electric, and permanent or moveable.

 

Nutrient Management Planning

A nutrient management plan is a written, site-specific plan that reduces nutrient pollution while maintaining crop production and, in some cases, increasing farm profits. By developing a “nutrient budget” for a farm and applying nutrients at the right time, with the right methods, a farmer can limit the amount of nutrients available to run off his land and into local waterways. While all farms will contribute some nutrients to the surrounding environment, those operating under nutrient management plans should contribute fewer nutrients than those farms that are not.

Most nutrient management plans focus on nitrogen and phosphorous and contain:

• A field’s crop production potential and the amount of nutrients needed to achieve this level of production
• Recommended application amount, form, source, rate, placement and timing of animal manure or commercial fertilizers

Livestock Manure and Poultry Litter

According to 2010 estimates from the EPA, livestock manure and poultry litter account for almost half of the nutrients entering the Bay. The states in the Bay watershed have committed to reducing this nutrient load by working with farmers to:

• Properly apply manure to cropland
• Develop animal waste storage systems
• Transport excess manure to areas in need
• Restrict or exclude animals from streams
• Locate or move livestock facilities away from streams

The Bay Program’s 2005 Manure Management Strategy identified four opportunities to better manage manure-related nutrient loads in the watershed:

• Adjust animal diets to reduce the amount of nutrients in manure
• Foster alternative uses for manure by building markets and technologies that use the livestock byproduct for energy, fertilizers, soil amendments or compost
• Develop a comprehensive inventory of manure nutrient surpluses in the watershed
• Coordinate manure management programs across the watershed to address regional manure imbalances or surpluses

Take Action

For Chesapeake Bay restoration to be a success, we all must do our part. Our everyday actions can have a big impact on the Bay. By making simple changes in our lives, each one of us can take part in restoring the Bay and its rivers for future generations to enjoy.

To support agriculture in the Bay watershed, consider purchasing products from a local farm. Buying local can reduce the pollution associated with transporting goods over long distances and the packaging needed to transport or store fresh produce. A number of area farms have even become involved in “agritourism,” which invites visitors onto farms to learn about local land and agriculture.

Learn more about farms across the watershed:

• Maryland Department of Agriculture
• Delaware Department of Agriculture
• Virginia Department of Agriculture and Consumer Services
• West Virginia Department of Agriculture
• Pennsylvania Department of Agriculture
• New York State Department of Agriculture and Markets

• News
• Video
• Publications
• Maps

From Around the Web

• Polluted Runoff: Agriculture - U.S. Environmental Protection Agency
• Pulling Together for a Cleaner Chesapeake Bay - Maryland Department of Agriculture
• Conservation Choices for Maryland Farmers - Maryland Department of Agriculture