A mixed blessing Part II
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 amount 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 dangers 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 groups of farmers, showing them that less fertilizer 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.
And fear of food scarcity still haunts Chinese imagination, outweighing concerns about the environment. Huang Jikun, director of the Center for Chinese Agricultural Policy, frequently tries to convince officials 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 like 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 agricultural production than does using that grain to directly nourish people. “If Chinese change their diet to be like yours [in the west], the environmental 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 Harlem 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, and barely.
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 made 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 feer the world. I say, that is not true. Look at this crop!”
Yet Rosmann’s methods carry their own cost. Farming this way takes more work, for one thing. And biology works more slowly than a nitrogen factory. The crops that build up the soil’s store of nitrogen, like alfalfa, don’t bring in as much money, or feed as many people, as nitrogen-hungry corn.
That’s not necessarily a problem for North America. The United States, with six times a much arable land per person as China, has the luxury of planting less-productive crops that protect the environment, if people are willing to pay for them. The setup works for Rosmann; he gets a small payment from the government, part of an environmental subsidy program, and sells his organic crops for premium prices.
Dan Charles
Source: DIJEST, January 2014