A mixed blessing Part III and Final
But will everyone pay the prices? Could his methods feed the world’s most populous country? Zhu Zhaoliang, in his office at the Institute of Soil Science in Nanjing, laughed out loud at the question. “Organic farming is not a solution for China,” he says flatly. Yet there may be middle ground-excellent harvests with reduced nitrogen pollution-and some of the world’s most intensely studied fields are pointing the way toward it. The fields, each exactly a hectare in size, are part of Michigan State University’s Kellogg Biological Station, near Kalamazzo. For 20 years these fields have been growing corn, soybeans, and wheat in exactly the same rhythm, providing a side-by-side comparison of four different ways to farm, ranging from mainstream to organic. Everything that enters or leaves the fields of carefully measured: rainfall, fertilizer, nitrous oxide emitted from the soil, water that leaches into groundwater, and finally the harvest.
Michigan State’s Phil Robertson, who helped set up this long-running experiment, takes me on a tour of the fields. He’s itching to reveal some new and “quite amazing” data. Each field planted according to standard plowing and fertilizer recommendations released 610 pounds of nitrogen per acre into Michigan’s shallow groundwater over the past 11 years. “So about half of the fertilizer that’s added we lose,” Robertson says. This loss is much less than what’s common in China. Yet when multiplied by tens of millions of acres of American cropland, it is enough to produce polluted groundwater, a nutrient-loaded Mississippi River, and an enormous dead zone in the Gulf of Mexico.
The organic fields in Robertson’s experiment, which received no commercial fertilizer or manure, lost only a third as much-but those fields also produced 20 percent less grain. Intriguingly, the “low input” fields, which received small amount of fertilizer but were also planted with winter cover crops, offered the best of both worlds: average yields were about as high as those from the conventional fields, but nitrogen leaching was much reduced, almost to the level of the organic fields. If America’s farmers could cut their nitrogen losses to something close to the level, Robertson thinks, restored wetland and revived small streams could clean up the rest. As in China, though many farmers find it hard to change. When a family’s livelihood is at stake, it may seem safer to apply too much fertilizer than too little. “Being a good steward currently has economic consequences that are unfair,” says Robertson.
Viewed from Africa, the problem of overusing commercial fertilizer seems like a luxury. African farmers use meager quantities of the stuff-just seven pounds per acre on average. Alternative sources, such as manure or legume crops, are scarce as well.
Many in Africa’s rural villages have fallen into a set of vicious circles. Fearing hunger, they concentrate on crops like rice or corn that deliver maximum calories but that tend to strip nutrients from the soil. Depleted land delivers increasingly poor harvests, leaving farmers too financially strapped to afford fertilizer, from whatever source. And since there is little demand for commercial fertilizer, no one makes it locally, so it’s imported and expensive.
According to many experts, African soils are being mined. The natural reservoirs of fertility-nutrients stored in the organic matter of decomposing roots and from previous centuries-are shrinking as farming extracts more nitrogen, phosphorous, and potassium every year than it replaces. This leaves the land progressively less able to feed the people who depend on it-“a scenario for disaster over the long run,” according to the World Bank.
The average grain yield in sub-Sahara Africa is about 900 pounds per acre, just one-fifth the average in China. Nearly everyone who’s looked at the situation agrees: African farmers need more nitrogen to improve their harvests and their lives. But there’s a ranging, bitter debate over where they should get it.
Some, like Jeffrey Sachs at Colombia University’s Earth Institute, believe that increasing agricultural production demands more commercial fertilizer, and if poor African farmers can’t afford it, then wealthier nations should provide it. In 80 villages across ten different African countries, Sachs’ Millennium Villages Project passes out bags of improved seeds and fertilizer. And the project’s having a big impact, according to its own data. In the millennium villages of Tanzania, Kenya, and Malawi, grain production doubled almost immediately.
In 2006 the government of Malawi started providing cheap fertilizer to about half of the nation’s farmers. Production of corn doubled-although good rains get much of the credit. These programs, however, are haunted by doubts about the future. Fertilizer subsidies were tried in many African countries during the 1970s and 1980s but fell out of favor because they were expensive and plagued by corruption. Malawi’s current subsidy program is already in trouble: the government is running out of money to pay for it.
“Africa cannot afford massive amounts of fertilizer,” says Sieglinde Snapp, a crop scientist at Michigan State University. A more sustainable approach, he says, is greater reliance on nitrogen-fixing plants. Thousands of farm families in Malawi have begun growing nitrogen-adding pigeon peas and peanuts on their land, replacing some of their corn. It’s part of the ten-year-old experiment begun by local farmers, and agricultural researchers.
Because peas made the soil more fertile, the next season’s corn harvest was larger-more than making up for the fact that less land was being planted with corn. “Less corn is more corn,” says Snapp. Plus that bonus crop of pigeon peas provided more nutritious protein-rich meals. “But it didn’t happen overnight,” says Snapp. “It took education on how to use the legumes. It was 20 years of work, with a hospital involved. People changed their recipes.”
Snapp’s observation-that acquiring and conserving nitrogen in the future will take considerable know-how and patience-is echoed by many people engaged in this worldwide quest. Asked what Chinese agriculture needs most, soil scientist Zhu Zhaoliand responds quickly. “More scale”-meaning larger, more skillfully managed farms. Ron Rosmann, in Iowa, explains that farming without added nitrogen “takes more management, more labor, and more attention to detail. We are kind of fanatics.”
A century ago, when chemist Fritz Haber first learned how to capture nitrogen from the air, synthetic fertilizer seemed like an easy shortcut out of scarcity, delivering a limitless supply of agriculture’s most important nutrient. Yet new limits on nitrogen are appearing. The time the innovations that save us-and our planet-may be invented in a chemistry laboratory. Instead they may come from farmers and fields in every corner of the world.
Dan Charles
Source: DIJEST, January 2014