A new report from the U.S. Department of Agriculture says that farmers aren't doing nearly enough to prevent pollution from cropland entering the Chesapeake Bay.

The draft report, "Assessment of the Effects of Conservation Cropland in the Chesapeake Bay Watershed," was put together by the USDA's Conservation Effects Assessment Project. It was released at a time when farm advocacy organizations from Virginia to New York have said their members are doing enough to control pollution from fertilizers, and resisting efforts that could force more, and faster, action.

"The report is so significant because it comes from USDA," said Gerald Winegrad, a former Maryland state senator and chairman of the 58 Senior Bay Scientists and Policy Makers for the Bay. "It's the acknowledgement of what people have known all along, that one, agriculture is the biggest source of pollution, and two, that agriculture is far from doing all that it can."

The report found that eight out of every 10 acres of cultivated farmland still needs better nutrient management. On two out of three of the acres, excessive levels of nitrogen are lost in subsurface pathways. On slightly more than one in four acres, not enough is being done to control erosion from sediment.

While cropland covers only 10 percent of the Bay watershed, the report says, they deliver 25 percent of the sediment, 27 percent of the phosphorus and 32 percent of the nitrogen to the Chesapeake Bay.

Patricia Langenfelder, president of the Maryland Farm Bureau, cautioned that the report was only a draft, and that looking at the watershed as a whole might not take into account the strides that Maryland farmers have made in reducing pollution. The popularity of cost-share programs, such as cover crops, suggests that farmers are doing their part, she said, but progress isn't going to be immediate.

"We're following the recommended practices," said Langenfelder, whose family farms 3,000 acres in Kent County, on the northern part of Maryland's Eastern Shore. "Obviously, at some point, this is going to make improvements. It's just not going to be instantly."

Beth McGee, senior scientist at the Chesapeake Bay Foundation, agreed that some progress had been made. But, she added, "we haven't made enough, and I think that is because we haven't had accountability and consequences like we have now," referring to the strict guidelines of the total maximum daily load, or TMDL - better known as the Chesapeake Bay's pollution diet.

McGee said she was impressed with the methodology the study used - a simulation model that differs from the Bay Program's model, but offers many of the same conclusions, such as pointing to agriculture as the largest source of nutrients reaching the Bay. While many farm organizations have criticized the EPA's Bay model as inaccurate, the similarities between the two methods reaffirms the Bay model's conclusions on agriculture, she said.

In fact, the USDA report indicated that about half of all of the nutrients in the Bay watershed originated from some type of agricultural land, slightly more than the EPA model had stated.

Of all the issues facing the Bay cleanup, agriculture has been particularly vexing. Despite millions of dollars spent and the widespread adoption of conservation practices, such as cover crops, scientists have seen little improvement in waterways where much of the land cover is in cultivation. Part of the problem may be the emphasis on complying with the letter of the law, but not the substance.

For example, a 1998 law in Maryland required all farmers to file nutrient management plans that spelled out how much phosphorus and nitrogen they would apply. But the state rarely inspected to make sure the plan was being followed. While most farmers say they follow the plans - they pay for them, after all - scientists have questioned whether that alone is enough to reduce nutrients.

The plans tell farmers how much nitrogen and phosphorus they can apply, but not what time of year, or where, or how to apply it, or what affect weather patterns may have on the possible pollution. That leaves a lot of discretion up to the farmer, who may not have the tools to apply the fertilizer in the least detrimental way.

"The recommended rates for nitrogen that are provided in those plans are really averages for the state or for the region. Those rates should be adapted for that farm," said Suzy Friedman, deputy director of working lands at the Environmental Defense Fund in Washington.

Through her organization's on-farm network, Friedman and her colleagues have been trying to get feedback on what actually works by testing corn stalks for nitrate levels after harvest and conducting aerial surveys. That information goes back to the individual farmer, who can then tweak his nutrient management plan for optimal results.

Buffers are an important conservation element, too, and while money has been available to create them, they are not always put in the most effective places, Friedman said.

"We're investing a lot in these nutrient management plans, and there is just significantly more benefit we can get if we fine-tuned this approach," she said. "We can use the existing pot of money a lot better."

Russ Brinsfield, executive director of the University of Maryland's Harry Hughes Center for Agro-Ecology, agrees that the focus needs to be not just on the application rates, but also their timing and method.

For example, science has shown that injecting fertilizer into the soil is "really important," Brinsfield said. The USDA's Agricultural Research Service has developed several manure-injecting techniques for farmers using dry poultry litter. But a lot of farmers in the Bay watershed still prefer to broadcast manure, because it takes less time.

Brinsfield, who is a farmer as well as a small-town mayor and scientist, understands well the farmer's predicament, especially in light of new limits coming from the TMDL. But he says the farmers can't continue to say they're doing all they can when the USDA has evidence to the contrary.

"I think it's going to be difficult for the agricultural community to keep saying 'we're doing our part' when a top agricultural regulator is saying we have got to do more," he said. "It's pretty remarkable, particularly coming from the USDA - I'm sure it wasn't planned this way, but I think the timing is really important."