That idea has become nearly gospel among China's 350 millionfarmers. Since 1977, they have nearly tripled fertilizer use,in part urged on by government subsidies and local officialswho take kickbacks from fertilizer sales. Today, China is theworld's largest user, consuming 36% of the global total of syntheticfertilizer.

The increase has helped farmers nearly double grain harvests.But it also exceeded soil needs, causing nitrates to accumulateand create serious pollution problems. And the hunger for nitrogenhas added to China's energy and greenhouse gas emissions: Inthe atmosphere, those nitrates form. nitrous oxide, a potentwarming gas.

Now, as the country attempts to coax even bigger harvests fromthe land, soil scientists want to end China's fertilizer binge.Through several promising demonstration projects, they are showingfarmers that reducing fertilizer use can improve crop yieldswithout adding to environmental problems. The new maxim, sayChinese soil scientists, is "Less input, more output."

Surprisingly, that strategy—making less fertilizer gofurther—could also hold promise for farmers in nationswith the opposite problem: too little fertilizer but a big needto increase soil fertility. The common solution? Helpingallfarmers get "high yield and high efficiency" in fertilizer use,says Zhang Fusuo, a soil scientist at China Agricultural University(CAU) in Beijing.

That message initially proved a hard sell in Cuidonggou, a villagenear Meng's greenhouse. When Chinese and British scientistsfunded by the United Kingdom's Department for InternationalDevelopment arrived in 2007 looking to recruit farmers willingto cut fertilizer use on half of their land, "at first no onebelieved what they said," recalls 61-year-old farmer Cui Tao.The scientists were calling for reducing fertilizer use by anaverage of 30% on winter wheat fields and 50% on maize fields.But farmers signed on after the scientists promised compensation,providing a cushion if yields fell.

The next harvest proved researchers right. Yields from the 30experimental plots were identical to or better than yields fromhigher-input fields. Farmers who adopted the low-nitrogen approachboosted profits by 1200 yuan ($176) per hectare, a sizable sum.Projects elsewhere produced similar results. Farmers in theTaihu and North China Plain regions have cut fertilizer useby 30% to 60% without reducing yields.

Now, researchers want to encourage farmers to try other low-fertilizertricks. For instance, by splitting applications into two smallerbatches—one before planting and one when plants are growingfastest—farmers can deliver nutrients when the crops needthem most.

Shifts in China's rural economy may hinder the spread of suchideas, however. Many young farmers now head off to constructionor factory jobs in the city after sowing their fields. Thatmeans they don't have time to apply nitrogen in multiple doses,and "increasing fertilizer efficiency takes time," says HuangJikun, director of the Center for Chinese Agricultural Policyat the CAU.

Other farmers are simply unwilling to risk cutting back. Tomatofarmer Meng, for instance, pays a hefty rent for his greenhouse.So, "as much fertilizer as I have, that's how much I use," hesays proudly.

Scientists also caution that the lessons learned here have limits.One reason some farmers aren't seeing lower yields, for instance,is because years of pollution and indiscriminate fertilizeruse have left China's , water, and soils overstocked withnitrogen. "At the moment, you can use up that stock in the camel'shump," says David Powlson, a soil scientist at Rothamsted Research,an agricultural institute in Harpenden, U.K., and lead scientistin the Cuidonggou project.

Still, researchers believe China can trim its fertilizer habit.Overuse has been a rite of passage for many industrialized countries,they note, including the United Kingdom, where use peaked inthe mid-1980s; yields have since gone up despite cuts. Chinanow has a chance to follow the same path, says David Norse,a professor emeritus in envieonmental management at UniversityCollege London. "We want to help them get away from this fearthat by reducing fertilizer they're going to be damaging foodsecurity," he says.

For other parts of the world, China's problems are a luxury.In sub-Saharan Africa, which uses a tiny fraction of the nitrogenChina applies, chemical fertilizer is expensive and livestockmanure scarce. But there, too, researchers are banking on theidea that less can mean more through an approach called "microdosing."

In recent trials in Zimbabwe, for instance, researchers fromthe International Crops Research Institute for the Semi-AridTropics in Malawi have shown that crops can thrive with as littleas a thimble-full of fertilizer applied close to the roots atthe time of sowing. Those microdoses boosted yields of maize,sorghum, and pearl millet by 30% to {bfb}.

Scientists say African farmers may also be able to minimizefertilizer use by improving irrigation and using better seeds,and—eventually—through new approaches to promotingthe growth of beneficial soil bacteria. The world's farmers"need fertilizer, but not only fertilizer," says CAUs Zhang."What they really need is integrated management."

That's a lesson China and other countries learned the hard way,Zhang says, adding that farmers elsewhere "do not need to repeatour mistakes."

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