“Such a marked difference in the vegetation can’t be a natural phenomenon,” says Wüpper, lead author of the study. “This example illustrates that the country in which the fields are located is a decisive factor for yield and nitrogen pollution,” he explains. “However, it would be possible for China to achieve a similar yield with significantly less nitrogen pollution.”
Also Switzerland is hardly a poster child for nitrogen pollution levels. Like other European countries, but considerably more, it continues to apply nitrogen fertiliser in great volumes that are too much for the crops to fully absorb. The surplus ends up in streams, lakes and other ecosystems.
“Agriculture in Switzerland is very intensive,” Wüpper says. He explains that this has a direct impact on nitrogen pollution, not least because the fodder that Swiss animals eat comes from abroad. However, the manure produced by the livestock is spread on Swiss soil, where it contributes to the levels of nitrogen pollution.
Economic instruments are one policy option
“Overall, however, there’s an uneven balance in the distribution of fertiliser resources around the globe,” the researchers say to sum up. While Switzerland has an oversupply, other regions of the world don’t have enough. In parts of sub-Saharan Africa, for example, farmers underuse nitrogen fertiliser. However, if they were to increase their use of nitrogen fertiliser only marginally, they would be able to significantly increase their yields. Mitigating this global fertiliser imbalance would enable yields to be considerably increased in some places and pollution to be greatly reduced in others.
One way to achieve this would be to adjust the cost of nitrogen fertiliser. In countries where too much is used, the cost of fertiliser should go up, e.g. by introducing a nitrogen tax, or by other policy instruments and adjustments. Conversely, in countries in which too little nitrogen fertilizer is used, the price should go down, e.g. by introducing a nitrogen subsidy, or by other policy instruments and adjustments.
Another approach involves changes on farms themselves. Government and industry could offer farmers incentives to make their crop production more environmentally friendly. They could, for example, promote certain production processes that increase the efficiency of nitrogen use. Moreover, farmers who use less nitrogen and consequently have to contend with lower yields could receive financial compensation from the state.
Huge potential in precision farming
New technologies could also increase nitrogen efficiency. “We’re talking about what’s known as precision agriculture, a concept in which fertiliser is applied only where it is actually needed. This can increase the efficiency of use and reduce environmental problems without decreasing output,” Finger explains.
“But consumption can also make a big difference,” Wüpper adds. He points out that one-third of all food produced goes to waste, intensifying nitrogen pollution and environmental damage. “If we cut down on food waste, we reduce environmental problems, too,” he says. A much meat-reduced diet also helps to cut back excess levels of fertiliser because if farmers produce less meat, less manure ends up on the fields.