National Geographic : 2013 May
108 national geographic • may 2013 108 damaging fisheries in China’s coastal areas in the same way that fertilizer runoff flowing down the Mississippi has destroyed fisheries in the Gulf of Mexico: by creating dead zones in which algae and phytoplankton bloom, die, and decompose, using up oxygen and suffocating fish. Our demand for food, to be sure, isn’t solely to blame. The combustion that drives cars and electric generators releases nitrogen oxides into the atmosphere, and when those compounds re- turn to Earth in drops of rain, they also act as fertilizer. (This accounts for about a quarter of the nitrogen load in Lake Tai.) But worldwide, commercial fertilizer adds up to 70 percent of the nitrogen that human activity produces every year. Nitrate-eating bacteria in the soil can convert these disruptive forms of nitrogen back to the original, environmentally benign source that makes up nearly 80 percent of our atmosphere. But even this process is a mixed blessing, as the bacteria also release small amounts of nitrous oxide, a powerful greenhouse gas. “ To solve this nutrient-overload problem, it is my dream,” says Xiaotang Ju, who is part of China’s “nitrogen family,” a loose network of scientists devoted to this herculean task. The patriarch of the cause, Zhu Zhaoliang, startled a conference of China’s ruling party in 1998 with a lecture about the dan- gers of agricultural pollution. China’s president at the time, Jiang Zemin, responded that he didn’t realize agriculture could pollute so seriously. These scientists have begun working with small groups of farmers, showing them that less fertil- izer doesn’t shrink their harvests and can actually fatten their wallets. They’re promoting the use of compost and teaching farmers to apply synthetic fertilizer when and where the plants actually need it. But they admit they’ve made little progress. The biggest obstacle is that most Chinese farmers are part-time. They aren’t interested in saving a few yuan by cutting back on fertilizer. It’s more important to save time and keep their city jobs, so they apply fertilizer quickly but inefficiently. And fear of food scarcity still haunts the Chinese imagination, outweighing concerns about the environment. Huang Jikun, director of the Center for Chinese Agricultural Policy, frequently tries to convince government of- ficials that their worries are misplaced. “I tell them, China is more food secure than it has been for 5,000 years!” he says. But for officials and farmers alike, applying less fertilizer seems like tempting fate, risking a disastrous shortfall. It’s likely that China—and the rest of the world—will use more nitrogen in the years to come, not less. Populations continue to expand, and meat is growing more popular. Feeding pigs or cattle demands several times more agricul- tural production than does using that grain to directly nourish people. “If Chinese change their diet to be like yours [in the West], the environ- mental pressure will be very high,” says Xiaotang Ju somberly. “We have to tend to this problem. Otherwise it will be really big.” THere’S A glImPSe of a solution on a farm just outside the small town of Harlan in western Iowa. Here 90 cattle graze on green pasture, and a few hundred pigs root about in beds of straw, surrounded by fields of alfalfa, corn, soybeans, oats, and barley. Ron and Maria Rosmann spread no nitrogen fertilizer on these fields, at least not the kind that comes from factories. Instead, it’s added biologically, by nitrogen-fixing bacteria that live in nodules on the roots of legume crops like soybeans, alfalfa, and a cover crop of clover that Ron Rosmann plants in the fall, only to till it back into the soil before he plants corn in the spring. Some of that nitrogen is captured in the corn, which he feeds to the pigs. Most of that ends up in manure, which goes back onto his fields, and the cycle starts all over again. Rosmann, unlike many other organic farmers, doesn’t buy manure from neighbors. “One of our goals has been to maintain a closed system,” he says. “We are a model for what organic farming should be like.” We wade into one cornfield. The stalks tower over our heads. “Look at this corn,” Rosmann exults. “We could have 200-bushel corn right here. A lot of naysayers will say, You organic guys can’t feed the world. I say, That’s not true. Look at this crop!” can organic methods feed the world’s most populous country? Zhu Zhaoliang laughs out loud at the question.