Robert Law raises sheep and grows sugar beets, wheat, barley oats and rye on his farm about an hour north of London. It's a big operation set on nearly 4,000 acres of rolling hills near the town of Royston, and there's one key ingredient that makes it all flourish–nitrogen fertilizer.
Law says he uses it for almost all his crops, because his land is inherently very low in naturally-available nitrogen, which plants need to thrive.
Law is hardly alone. The invention of nitrogen based fertilizer in 1909 helped fuel a global agricultural boom, and it's been crucial in feeding a growing population ever since.
But a growing number of scientists say that boon to our food supply has come at a big cost–massive nitrogen-based pollution.
Mark Sutton, of the Center for Ecology and Hydrology in the United Kingdom, sums up the dilemma: "We've known for many years that using nitrogen for fertilizer is a great thing for farming to increase productivity," Sutton says. "But there's a whole range of threats resulting from this nitrogen leaking into the environment."
Nitrogen itself is an inert gas that's necessary for life. But Sutton says we're changing it into forms that are harmful, overloading the environment with it, and throwing the natural nitrogen cycle out of whack.
Nitrogen compounds running off farmland have led to water pollution problems around the world, while nitrogen emissions from industry, agriculture and vehicles make a big contribution to air pollution.
"Massive cost" from Nitrogen Pollution in the EU
Sutton says the cost of all of these impacts is immense. Last year he was part of a team of 200 scientists from 21 countries who studied the problem in the European Union. They calculated the dollar value of the damage of nitrogen pollution at between 90 and 400 billion dollars a year.
That's "a massive number," Sutton says.
The cost comes to both the environment and human health. For instance, Sutton says, particulate air pollution caused in part by nitrogen shortens the lives of many Europeans by more than a year.
Overall, the EU report estimated that the cost of nitrogen pollution in the EU is more than double the value that nitrogen fertilizers add to European farm income.
"So these are significant issues," Sutton says.
The EU study is the first to calculate these costs in Europe. But Alan Townsend, an ecologist at the University of Colorado, says nitrogen pollution is "unquestionably" a global problem.
Townsend says the US is also a major hotspot, and that big problems are emerging in China, Southeast Asia and Latin America.
The impacts of nitrogen pollution can be hard to recognize. Big environmental disasters like oil spills tend to grab all the attention, Townsend says, but "there is essentially a nitrogen spill everyday."
The irony is that in the right places and chemical forms, nitrogen is valuable stuff. Every ounce of fertilizer that runs off a field into a river is a waste of resources and money.
"Solutions are Right in Front of Us"
But Townsend says it's a problem that shouldn't be that hard to solve.
"This is not one of those problems where we sit around scratching our heads and say, 'Man this is going to be a disaster, how are we going to deal with it, there's nothing we can do,'" he says. "A lot of the solutions are right in front of us. It's just about moving down that path."
That path includes increasing the use of technology to cut nitrogen pollutants from power plants and vehicles, which is already widely used in the US and Europe.
Cutting nitrogen pollution from food production is a more complicated challenge, but Townsend says on the farm field itself, it comes down to a simple principle: use fertilizer more efficiently.
"We have to approach it as an efficiency problem," he says. "How do we maximize the benefits that we're going to get from this stuff and minimize the unwanted consequences?"
Royston farmer Robert Law is trying to rise to that challenge. He prides himself on running a farm that's not only productive, but environmentally sensitive.
His tractor now sports a small computer console with which his farmhands can ensure that each field gets only the exact amount of fertilizer it needs, depending on the crop, the season and the weather.
"We just program each individual field as we come to it," says Law's farmworker Mark Moule. "Just press start and finish and one minute you'll be putting 50 kilos on per hectare next minutes it's a hundred and fifty."
That kind of precision helps reduce the amount of nitrogen that runs off farm fields into nearby streams. It can also help save money on fertilizer.
Economic & Demographic Challenges
But this kind of technology is expensive, and many smaller farms can't afford it.
For his part, Law is willing to look for even more efficient ways to use fertilizer. But he warns that Britain and the rest of the world face a growing challenge when it comes to feeding a growing population.
"The area available for farming in this country is getting smaller each year," Law laments. "Roads are being built, towns are being built."
It's a global trend–less farmland and more mouths to feed. And that will only add to the challenge of getting rid of the excess nitrogen we've been putting into the environment.