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Why is agriculture important?

Agricultural land covers nearly one-quarter of the Chesapeake Bay watershed. There are more than 87,000 farm operations and 6.5 million acres of cropland here. Farms in the Bay watershed produce more than 50 commodities, including corn, wheat, soybeans, fruits and vegetables. Agriculture is essential; farms supply us with meat, milk, grains, eggs and vegetables.

How does agriculture affect the Chesapeake Bay?

Agriculture is the largest single source of nutrient and sediment pollution to the Bay and its rivers. Common farming practices such as applying fertilizer and tilling soil can contribute harmful pollution to the Bay and its local waterways.

Irrigation

Irrigation is a common method for farmers to water their crops to ensure consistent crop production in a variety of weather conditions. Fruits, vegetables, grains and horticultural plants are the most commonly irrigated crops on Bay watershed farms.

Excess water from irrigation that is not absorbed into the soil may run off fields and into nearby waterways, carrying fertilizers, soil, pesticides and manure along with it. Increased amounts of water soaking into the soil may also transport dissolved nutrients from commercial fertilizers, livestock manure and poultry litter into groundwater supplies.

Fertilizing Soil

Commercially manufactured agricultural fertilizers provide crops with the nutrients they need to grow. When more fertilizer is applied to the soil than crops can absorb, excess nutrients can:

• Be washed off the land via runoff into the nearest water source.
• Soak through soil and bedrock into groundwater supplies.

Excess nutrients like nitrogen and phosphorus fuel the growth of algae, creating dense algae blooms that rob the Bay's aquatic life of sunlight and dissolved oxygen.

Animal Manure

Animal manure is often applied to cropland as a form of fertilizer because it contains nutrients that help crops grow. However, when excess manure is carried from the land via runoff, those nutrients, as well as bacteria and pathogens that manure often contains, can end up in our waterways. Excess nutrients from manure can also absorb through the soil into groundwater supplies, contaminating local waterways and drinking supplies.

Animal manure and poultry litter contribute about half of the Bay watershed's agricultural nutrient load.

Managing manure and poultry litter is a major component of farms that run animal operations. As cropland is increasingly converted to development and other non-agricultural uses, less cropland is available to efficiently use the manure and litter being produced by animal operations in the watershed. Producers have alternative options for their manure and litter, but transportation costs, access to markets or equipment and infrastructure requirements may prohibit them from taking part.

Applying Pesticides

Chemical pesticides and herbicides help protect crops from insects, weeds and fungus. Just like fertilizers and manure, when pesticides are applied in excess, they can make their way into local rivers and streams and potentially impact aquatic life. Pesticides can also soak into groundwater supplies, a source of drinking water in many Bay watershed communities.

Tilling Cropland

Tillage loosens the soil and makes it easier to uniformly plant crops; but in the process, it leaves soil prone to erosion. Loosened soil that is transported by runoff can cloud the water in rivers, streams and the Bay and limiting the amount of sunlight able to reach underwater bay grasses. River basins in the Bay watershed with the highest percentage of agricultural land yield the highest overall amount of sediment each year.

How is the Bay Program working to reduce pollution from agriculture?

Bay Program partners are working with farmers throughout the region to help control pollution from the Chesapeake Bay watershed's approximately 9 million acres of farmland. In part because they are so cost-effective, the states in the Bay watershed are relying on expanded use of agricultural conservation practices for more than half of the remaining nutrient reductions needed to meet overall Bay restoration goals.

Common Agricultural Conservation Practices

As part of their tributary strategies, the Bay states are implementing nutrient management plans and key conservation practices, also known as best management practices or BMPs. Some conservation practices are voluntary or incentive-based, while others — such as nutrient management planning for all agricultural operations in Maryland — are mandatory.

Nutrient Management Planning

A nutrient management plan is a written, site-specific plan that helps to reduce nutrient pollution while optimizing crop production and farm profits. Even farms under the best nutrient management plans will still contribute some nutrients to the environment; however, the amount should be less than what would be contributed without a plan.

Nutrient management plans are tailored to each specific site, but generally contain:

• Soil information for a particular field or operation.
• A field's crop yield potential and the amount of nutrients needed to achieve this yield.
•  Recommended application rates for manure or commercial fertilizers, based on nutrient carryover from previous applications and crop rotations.

Cover Crops

Cover crops, planted in fall after the autumn harvest, usually consist of cereal grains such as wheat, rye and barley that grow throughout winter. Once established, cover crops absorb excess nutrients in the soil and help prevent soil erosion, reducing pollution to local waters.

In addition to helping the Bay, cover crops benefit farmers by retaining nutrients for future crop needs, reducing soil compaction and increasing organic matter in the soil. Cover crops also help block out harmful weeds.

Animal Manure and Poultry Litter

There are multiple solutions for reducing nutrient loads from animal manure and poultry litter, which contribute about half of the nutrients that come from Bay watershed farmland. The states in the Bay watershed have committed in their tributary strategies to reduce nutrients from manure and litter by working with farmers to:

• Properly apply manure and litter to cropland.
• Develop animal waste storage systems.
• Restrict animals from streams.
• Relocate livestock facilities away from streams.
• Transport excess manure and litter to areas in need.

The Bay Program's 2005 Manure Management Strategy identified four opportunities to better manage nutrients from manure:

• Adjust animal diets to reduce surplus nutrients in animal manure and poultry litter.
• Foster alternative uses for animal manure and poultry litter nutrients by building markets and technologies for manure and litter products that can be used for energy, fertilizers, soil amendments or compost on a variety of lands.
• Develop a comprehensive inventory of manure and litter nutrient surpluses in the watershed.
• Coordinate manure management programs throughout the watershed to address regional imbalances of manure and poultry litter surpluses.

Grass and Forested Buffers

Grass and forested buffers planted along the edges of farm fields and livestock pastures reduce the amount of pollutants able to flow into nearby streams and rivers. Trees and other vegetation also stabilize stream banks, as well as slow and absorb pollution that would otherwise run off fields and into local waterways.

Conservation Tillage

Conservation tillage is any tillage planting system that leaves at least 30 percent of a farm field covered with crop residue or vegetation throughout the year. By reducing tillage or leaving the soil undisturbed, fields are less prone to erosion. No-till and minimum-till farming are forms of conservation tillage.

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From Around the Web

• Polluted Runoff: Agriculture - U.S. Environmental Protection Agency
• Helping Farms Help the Bay - USDA Natural Resources Conservation Service
• Resource Conservation - Maryland Department of Agriculture
• Agriculture and Its Effects on Groundwater - Virginia Tech