Environmental pollution through fertilizer: do farmers contaminate the water?

The taz fact check shows: The average farmer fertilizes too much and pollutes the groundwater. This is a danger to health and the environment.

Here comes the nitrate: farmer in Lower Saxony spreads liquid manure as fertilizer on a field Photo: Philipp Schulze/dpa

Many farmers feel unjustly pilloried by environmentalists, politicians and journalists. This was shown, for example, by the demonstrations of thousands of farmers in several major cities on October 22. On November 26, tractors are to roll into Berlin again.

Among other things, the movement denies that farmers are responsible for the contamination of groundwater by nitrate, a nitrogen compound that is potentially harmful to health and the environment. Thus, these farmers argue against the planned regulation of the federal government to fertilize less with nitrogen. Berlin wants to prevent a fine from the EU because, according to the European Court of Justice, Germany has been violating the nitrate directive for years. In addition, Deutsche Umwelthilfe wants to take legal action against the state governments of Lower Saxony and North Rhine-Westphalia for exceeding the nitrate limit in groundwater. Here is a fact check of the most important claims made by the agricultural side:

If the nitrate limit of 50 milligrams per liter is exceeded in drinking water, this is far from being harmful to health.

False. Even if the limit is exceeded only occasionally, babies can get cyanosis, according to the Federal Environment Ministry. That’s because nitrate can be converted by bacteria into nitrite, which disrupts oxygen transport through red blood cells. "This can lead to oxygen deficiency in the tissues and even internal asphyxiation," writes the Federal Institute for Risk Assessment.

Our drinking water is almost always below the nitrate limit. It is not a big problem that a few groundwater bodies are above this level. Groundwater is not just drinking water.

According to the Federal Environment Agency, drinking water actually complies with the limit value across the board. But only because the waterworks blend groundwater from wells that are too heavily contaminated with nitrate with clean water from other wells, close contaminated wells, drill deeper or filter out the nitrate. Nearly 70 percent of drinking water is obtained from groundwater and spring water, according to the Federal Environment Agency.

Agriculture is not even the main source of nitrate emissions in Germany, it said.

But, most of the nitrate in groundwater comes from agriculture. This is documented, for example, by the Federal Environment Agency in its research project "Reactive Nitrogen Flows in Germany 2010-2014," the results of which are to be officially published soon. According to this, 88 percent of the nitrate in groundwater comes from agricultural land below the root zone, as the Federal Environment Agency told the taz in advance.

In addition, measuring points in the catchment area of farmland have significantly higher nitrate concentrations in the groundwater than measuring points whose catchment area is predominantly characterized by forests: under forest areas, the threshold value of 50 milligrams per liter is exceeded at 2 percent of the measuring points, according to the Federal Environment Agency. At measuring points where grassland or settlements dominate the catchment area, this proportion is 8 and 6 percent respectively. In regions where arable land or special crops predominate, the threshold value is exceeded at 33 percent of the measuring points.

Leaky sewage pipes pollute the groundwater much more with nitrate than agriculture.

This is also wrong, as a study for North Rhine-Westphalia, the German state with the largest population, shows. The Federal Environment Ministry quotes the result as follows: "No groundwater body in NRW is in poor condition because of nitrate due to a source other than agriculture." It is true, according to the researchers, that there are selective loads from leaking canals. But the inputs are so limited locally that they are not significant, he said.

Germany has fewer groundwater measuring points per area than other EU countries. That is why the results are distorted.

In fact, according to the EU Commission, the monitoring network in Germany is not as close-meshed as in most other member states. But according to the authorities, this does not change the fact that the German results are representative. The network used for reports to the European Environment Agency (EEA), for example, consists of 45 percent monitoring sites under cropland, 11 percent under grassland, 30 percent forest and 9 percent settlement land, according to the German government. "This reflects the area shares of the individual land uses in Germany," the government said. About 18 percent of the monitoring sites in this network are above the threshold for nitrate, according to the Environment Ministry.

The federal government now wants to mandate that farmers in particularly polluted areas fertilize 20 percent less than was previously officially considered necessary, it said. Then the plants would starve.

That would only be true if farmers had previously only fertilized as much as the plants absorbed. But that is precisely what they have not done. Take Lower Saxony, Germany’s No. 1 agricultural state: In the past fiscal year, farmers there fertilized an average of 19 kilograms of nitrogen too much per hectare, according to the nutrient report published by the Ministry of Agriculture, which is led by the pro-agriculture CDU party. It is true that the fertilizer ordinance is supposed to limit the amount so that hardly any nitrogen remains. But it offers many loopholes. In addition, some farmers don’t follow the rules, which are often enforced laxly. Some farmers want to dispose of the huge amounts of manure from mass-produced barns in the fields by over-fertilizing. Sometimes farmers simply err and fertilize too much or at the wrong time.

Plants do not starve even if they receive less fertilizer, says Onno Poppinga, professor emeritus of agriculture and co-founder of the Arbeitsgemeinschaft bauerliche Landwirtschaft, to the taz. "They can continue to germinate, grow and come to seed maturity." But maybe the harvest wouldn’t be as big as farmers wanted. Fertilizer regulations define a crop’s needs so farmers can harvest and earn as much as possible, he said.

If farmers in particularly polluted areas fertilized 20 percent less than currently allowed, that would do little good for groundwater.

Henning Kage, an agricultural professor from Kiel, writes that fertilizing less reduces the amount of nitrate in the groundwater "generally only very slightly in the short to medium term (1-10 years)." This is confirmed by Hans-Werner Olfs, Professor of Plant Nutrition at Osnabruck University of Applied Sciences. This is because the nitrate-contaminated rainwater takes a long time to seep through the various soil layers into the wells. "After that, however, the nitrate levels in the groundwater will very likely drop significantly," Olfs told the taz.

Harvests will shrink sharply if crops are allowed to receive less fertilizer. Many farms would have to close.

"We estimate that yields of arable crops will fall by an average of 5 percent if they are fertilized with 20 percent less nitrogen than is allowed under the 2017 fertilization ordinance," says Bernhard Osterburg, a scientist at the federally owned Thunen Agricultural Research Institute who is also recognized by environmentalists. In addition, it would then become more difficult to achieve the qualities required on the market, especially for baking wheat and some field vegetables. Agricultural professor Kage estimates that farmers would earn a total of 150 million euros less per year because of the fertilizer reduction. Whether this reduction in profits would threaten the existence of the farmers could "only be assessed on a farm-by-farm basis.

It is not justified, he said, to reduce the maximum allowed fertilization even for farmers who work in polluted areas but have not applied too much nitrogen themselves.

The Environment Ministry disputes that: "Farms that farm in a way that protects water bodies should be exempt." A farm is considered water-friendly if it uses less than 160 kilograms of total nitrogen per hectare and a maximum of 80 kilograms of synthetic nitrogen fertilizer. The farmers’ association does not deny this when asked by the taz. This exception is "self-evident", says Secretary General Bernhard Krusken.

Nitrate is naturally broken down in the soil and groundwater.

"All currently known scientific studies give no indication that natural denitrification, i.e. nitrate degradation in the unsaturated zone and in groundwater in Germany, can reduce nitrate concentrations on a large scale," the Environment Ministry writes. In some regions, nitrate is currently still being degraded. But how long this capacity will last is unknown. Therefore one cannot rely on it. The farmers’ association did not want to comment on this when asked by taz.

The fact that agriculture has a nitrogen surplus of about 100 kilograms per year and hectare does not mean that farmers are fertilizing this amount too much.

That’s true. Some of the nitrogen does not enter the environment through fertilizing, but rather, for example, when liquid manure is stored in the open air. But that doesn’t change agriculture’s responsibility for these emissions, which can also be reduced. Nor is it because they often fertilize too much, as the nutrient report for Lower Saxony shows, for example.