• October 10, 2015

Nutrients a factor in Bay quality, dead zones - The Star Democrat - Easton, Maryland: Chesapeake Bay

Nutrients a factor in Bay quality, dead zones

Font Size:
Default font size
Larger font size

Posted: Thursday, February 13, 2014 3:30 am

EASTON — Younger generations, those of us born in the 1980s to today, might hear stories of crystal clear Chesapeake Bay waters and believe those stories are myths. Bay water quality has changed, is ever changing, and human activity is a major reason why.

Agricultural activity and urbanization contribute sediments and excess nutrients, specifically nitrogen and phosphorus, that are known to have detrimental effects in the Bay.

Tom Fisher is a 35-year faculty member, researcher and scientist at University of Maryland Center for Environmental Science at Horn Point Laboratory.

“You talk to people who grew up here in the ‘40s and ‘50s, and they will tell you that the water was clear. You could see the bottom. There were grasses everywhere,” Fisher said. “Those days are gone. You walk out on a dock. You look at the water, it’s green. It’s green from the phytoplankton.”

Phytoplankton, commonly known as algae, feed on excess nitrogen and phosphorus in a process known as eutrophication which depletes oxygen in the water.

Beginning every year in spring, usually April or May, and continuing through summer, a dead zone recurs in the Bay. Evidence of this phenomenon dates back more than 60 years, according to Jamie Pierson, a biological oceanographer at Horn Point since 2006.

Many scientists right here on the Mid-Shore and nationwide agree that dead zones, also studied in other bodies of water like the Mississippi and Gulf of Mexico, are exacerbated by human activity. In the Bay, nitrogen and phosphorus runoff is a main contributor to the growing dead zone.

“There’s good published data tracing it back through to at least 1950,” Pierson said in a January email, “with increasing severity (e.g. size of the dead zone) since then, largely attributed to increasing nutrient inputs.”

Gregory Farley is associate professor of biological science and director of the Center for Leadership in Environmental Education at Chesapeake College.

“Excess nutrients — particularly phosphorus and nitrogen, which are best-studied in the Bay watershed — are clearly understood to have a detrimental effect on water quality,” Farley said in a January email. “It’s important to understand that these nutrients do occur naturally, and would, in a totally natural situation, still be found in the Bay as a byproduct of forest processes, natural decomposition, and the like.

“However, the levels of these nutrients that we measure in today’s Bay are in excess of natural levels, and they enable the growth of huge populations of naturally occurring phytoplankton in the Bay.

“This, in turn, sets off an explosion in the planktonic food chain, which leads to huge numbers of dead plankton, which leads to bacterial blooms during decomposition, and it’s the activity of these decomposer bacteria that consume all available oxygen in some regions of the Bay, causing ‘dead zones.’ That oxygen stress is detrimental to other forms of life, especially organisms that can’t get away from it.”

Pierson’s studies point to the same effects of dead zones.

“If you think about what might happen, things that can move will move and those that are stuck on the bottom will die when you get hypoxic (extremely low oxygen) conditions,” he said in an email. “A lot of those bottom-dwelling organisms are not used to swimming long distance — they are ambush predators and such — so the forced migration can be pretty stressful.”

Pierson said that in other places like the Gulf of Mexico, “people have seen animals stack up on the edges of dead zones (shrimp, crabs, fish) because they are forced to move. On the bottom, people have seen (using underwater video) dead clams and worms that suffocated because they couldn’t move fast enough, if at all.”

In spring, as water temperatures near the Bay’s surface rise and plankton and algae begin to grow, the dead zone appears in the deep water channel near the William Preston Lane Jr. Memorial (Bay) Bridge. Depending on seasonal conditions, the dead zone can stretch as far south as the mouth of the Rappahannock River.

On Dec. 29, 2010, the Environmental Protection Agency issued an executive summary “Chesapeake Bay Total Maximum Daily Load for Nitrogen, Phosphorus and Sediment.”

TMDLs represent “a historic and comprehensive ‘pollution diet’ with rigorous accountability measures to initiate sweeping actions to restore clean water in the Chesapeake Bay and the region’s streams, creeks and rivers,” according to the summary.

The report, based on controversial Chesapeake Bay Watershed Model data from 2009, shows Maryland contributed 20 percent of nitrogen and phosphorus to Bay waters. Among the jurisdictions in the Bay watershed — Delaware, Maryland, New York, Pennsylvania, Virginia, Washington, D.C., and West Virginia — Pennsylvania contributed the most nitrogen at 44 percent and Virginia contributed the most phosphorus at 43 percent.

Among jurisdictions in the watershed, agriculture is a key source of nitrogen and phosphorus, contributing between 30 and 40 percent of the nutrients, according to the model.

“Integrated across the Bay watershed as a whole, agriculture is the single largest contributor,” Fisher said, “contributing about (one-third) of the total (nitrogen) and (phosphorus).”

Nitrogen and phosphorus are key components of fertilizer that enter groundwater and run off if not absorbed by plants.

Jim Lewis is senior agent at the University of Maryland College of Agriculture and Natural Resources Caroline County Extension. He acknowledged that agriculture affects Bay water quality, but said farming practices have improved since World War II. The introduction of man-made fertilizers, pesticides, genetically modified crops and better land use has enabled farmers to grow crops more efficiently.

“No matter what crop it is, we’re growing three or four times as much now as we were back then,” Lewis said. “We’re using more fertilizer because we’re growing a lot more corn or wheat, but per bushel or per pound of corn produced, we’re using less fertilizer than what was used in the ‘50s and ‘60s. ... We may have doubled fertilizer use, but we’ve tripled or quadrupled grain production.”

With few exceptions, farmers in Maryland are required to submit nutrient management plans to Maryland’s Department of Agriculture. NMPs are meant to produce sufficient crop yields while ensuring that farmers and urban land managers use manure, fertilizer and other nutrients in an environmentally sound way.

Lewis, a lifelong Caroline County farmer, said the extension office helps produce NMPs for roughly 40 percent of farmers in his coverage area on the Upper and Mid-Shore.

Though NMPs are meant to reduce the amount of nutrients entering the Bay, Lewis said economics play a major role in Bay stewardship. He said farmers didn’t understand the nutrient value of manure in the 1970s and ‘80s were using additional man-made fertilizers to ensure crop growth.

“University research is what started to show people that manure had nutrient value and had a lot of fertilizer in it and it shouldn’t be used like that. People were using manure and then also using fertilizer. Crop prices were decent. Fertilizer prices were cheap. So it was cheap insurance. So they were just putting extra fertilizer on it anyway. It couldn’t hurt anything,” Lewis said. “So from the ‘70s and ‘80s until now, crop budgets or farm budgets and the farmer’s bottom line reduced. And it just got to be because of economics, farmers were looking at ways to save money to cut expenses, and realizing that manure had nutrient value.”

At 45 years old, with a bachelor’s degree in crop science, and master’s degree in wheat science from the University of Maryland College Park, Lewis is a student of the history of agriculture in the U.S. Having grown up on a farm, working since he was 5 years old, he also can speak to changing practices.

“I’ll admit that my dad and I, when I first started farming, polluted. We didn’t know any better. The research just wasn’t there. We used to use manure and didn’t give it any value. It was just a waste product that we had to get out of the manure building or out of where the chickens or the cows were. … It just went out behind the barn in the field,” he said. “We just got rid of it. Now we actually give it a value. … Most farmers would admit that back in the ‘60s and ‘70s and early ‘80s they did things wrong, but not now.”

Along with a growing group of Maryland farmers, Lewis uses a number of best management practices. BMPs are structures or practices that help reduce nutrient runoff in both agricultural and urban areas. BMPs range from winter cover crops, forested buffer zones and drainage control structures on farms to rain gardens, rain barrels, and non-fertilized lawns in residential areas.

Among these practices, Lewis said the Maryland Cover Crop program is the most important. Farmers are encouraged to grow cover crops like rye and winter wheat to reduce nutrient runoff during winter. Overseen by the Maryland Department of Agriculture, the state will pay up to $45 per planted acre along with additional incentives to participating farmers.

“Per pound of nitrogen saved, one of the cheapest ways to do it is cover crops,” Lewis said. “But that’s a program that not many farmers would do ... if it wasn’t for some sort of subsidy. They’ve got to buy the seed. They’ve got to plant it, then they’ve got to kill it. They’ve got to get it planted in the fall when they’re trying to harvest crops to sell, so it’s a difficult time of year. There’s just various issues … There needs to be a subsidy for them to justify planting it.”

According to statistics from Gov. Martin O’Malley’s office, in fall 2007, the state spent $7.7 million to subsidize 203,000 acres of cover crops. In 2012, acreage more than doubled to 413,300 and the state provided $22 million for cover crops.

Despite the growing success of the cover crop program, urban and suburban runoff are increasing sources of sediment, nitrogen and phosphorus. Impervious surfaces like roads, parking lots and roofs that don’t absorb water expand with the population.

“The one sector that’s growing most rapidly in terms of nutrient pollution is urban storm runoff. Towns are growing. Suburban areas are popping up,” Fisher said. “Impervious surfaces, that part of the Chesapeake Bay basin is increasing in area, and the amount of pollution, nitrogen and phosphorus and sediment coming off those areas is increasing.”

Fisher said the best way residents of the Bay watershed can help is to stop fertilizing their lawns.

“The Chesapeake simply can’t afford lawn fertilizer. My opinion … is it ought to be banned from the whole Chesapeake basin,” Fisher said while suggesting other residential BMPs. “For residences, we’ve got to eliminate lawn fertilizers. Put in swales or rain gardens or rain barrels. Put in denitrifying septic systems. Put in buffers around streams or ditches or on property, essentially reducing the impact of the residence and the lawn and garden area.”

A concerted effort from residents of the Chesapeake Bay Watershed, urban, agricultural and rural, is needed to see real improvement.

“We’re asking farmers to do a lot of things, but we’re also asking urban, city dwellers to do the same thing,” Fisher said. “Everyone’s made a contribution to these problems we’re talking about here.”

More about

More about

Welcome to the discussion.

Connect With Us