Modern agriculture is practically unthinkable without synthetic fertilizers. It increases harvest yield, secures food supplies for many people and keeps space requirements relatively low.
However, its use also has side effects such as excess nutrients in the water and the release of greenhouse gases. Therefore, research teams are working on ways to improve the ecological balance.
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Feeding three billion people
Fertilizers supply plants with nitrogen, among other things. The element makes up 78 percent of the air, but few plants can use the nitrogen in the atmosphere. Plants such as fields, soybeans, alfalfa, lupins, peas, and legumes cooperate with soil microbes called roots or nodule bacteria. Microbes contain an enzyme that plants lack and convert atmospheric nitrogen first into ammonia and then into compounds that plants can use. In return, they provide the bacteria with energy in the form of sugar.
So farmers have been including legumes in crop rotation for centuries. Plants leave something behind: about 20 to 70 kg of nitrogen are left per hectare for the next crop. In organic farming, this principle is still used to this day to improve the supply of all crops – as well as manure from animal husbandry.
However, it is doubtful that conventional agriculture can do without synthetic fertilizers. Your returns per region are much higher. According to estimates, an additional three billion people live in the world because they can be fed thanks to synthetic fertilizers.
High prices can lead to starvation
Synthetic fertilizers have become more expensive as a result of rising prices for raw materials, and inflation, in addition, is driven by the war of aggression in Ukraine with its consequences for production: since the beginning of 2020, it has increased three to four times, as analyzed. by CRU Group in London. Little is sold, with dire consequences.
“If the market does not cover even one percent of fertilizer demand, as many as 32 million more people will suffer,” says Matthias Berninger, head of public affairs, science and sustainability at Bayer in Leverkusen. The company does not sell the fertilizer itself, but is looking for ways to reduce the need.
One possibility: to use soil microbes in such a way that the known nitrogen fixation of legumes would also work in other plants. Biotech companies like Joyn Bio and Pivot Bio are looking into this. They analyze how different microorganisms in the soil interact with plants.
From the wealth of data, processes that can also contribute to the supply of crops such as corn, wheat or rice are filtered out by microbial-based nitrogen enrichment. Researchers identify the genetic sequences needed to serve and insert them into the DNA of microorganisms suitable for coexistence with desired plants.
“These organisms can, for example, be placed directly on the seed, experts say, ‘dressing,’ so that they are close to the developing roots and can nourish the plant,” explains Berninger. He estimates that in about five years, the process could be ready for practical use.
Controversial genetic engineering
He is familiar with the discussion about GMOs in agriculture. He responds to critics: “All the processes that happen there happen in nature anyway.” Microbes also die in the fall because the host plants are no longer present after harvest. “But of course, you have to have a certain creative spirit or come to terms with the fact that you keep using a lot of synthetic fertilizers.” He believes that it is impossible to do without synthetic fertilizers and genetic engineering, and cites the example of Sri Lanka.
The country wanted to be the first in the world to practice exclusively organic farming. In the spring of 2021, President Gotabaya Rajapaksa imposed a complete ban on synthetic fertilizers and chemical pesticides. As a result, many farmers abandoned their cultivation areas and food became scarce. Although the ban has since been lifted, Sri Lanka is mired in a severe economic crisis. Because of the shortage, there are always riots.
Another way to meet nitrogen needs is within the plants themselves – at least some. For example, an ancient variety of corn that still grows in the Sierra Mexicana was able to use up atmospheric nitrogen. The researchers found that it also cooperates with soil bacteria. The assumption has been around for years, but only modern research methods have confirmed this now.
Atmospheric nitrogen in plants ranges between 29 and 82 percent, according to a team led by Alan Bennett of the University of California, Davis, in the journal PLOS Biology. Scientists are now trying to introduce this property into traditional varieties.
It will not be easy, ancient wild varieties and modern high-performance plants are very different. But the potential is great, as with genetically modified microbes, if fertilizer requirements for mass crops such as corn, grains and rice can be reduced in this way.
Eight tons of wheat per hectare can be harvested on good soil as in Magdeburger Börde; Plants need about 180 kilograms of nitrogen for this purpose, estimates Nicholas von Wehren of the Leibniz Institute for Plant Genetics and Crop Plant Research (IPK) in Gattersleben. “If you can save 50 or even 100 kilograms per hectare, that will be a huge advantage,” says the head of the Department of Physiology and Cell Biology. But he doubts that the aforementioned measures will be implemented soon. Identification of affected gene segments is only the first step. “Then it must be checked whether the mechanism is working reliably.” This also included field trials.
In Germany, no longer a researcher would dare to do so. The applications are very complex, and the fear of field destroyers in their fight against GMOs is too great. So scientists are testing in other European countries and North America, for example, whether genetic modifications can make plants more tolerant of heat and drought or reduce the need for fertilizer. In a few years at the latest, the question will arise again: Is society in this country willing to accept such methods if they prove safe and effective?
Save here, use there
Genetic engineering in agriculture is not only discussed due to the current rapid rise in fertilizer prices. Fertilizers also have a negative impact on the climate: about four percent of global greenhouse gas emissions can be traced back to their use. This is laughing gas, which is produced from nitrogen fertilizer because it is not completely converted by plants.
The other part comes from the production of ammonia from raw materials. Nitrogen from air and hydrogen from natural gas are used for this. This process is energy-intensive, worsening the greenhouse gas balance. Unless the hydrogen and the required energy came from renewable sources. Research is being done in industry, also because ammonia can become an important energy source in shipping.
Many companies want to produce green ammonia. In addition to Australia, Norway is also set to become an important location. In 2021, three large companies there joined forces for the “Hegra” project to convert the existing ammonia plant in Herøya. According to the company, within five to seven years, it will become the world’s first zero-emission fertilizer plant on an industrial scale.
Until then, using fertilizer sparingly can help. Some farmers work according to the principle of “a lot helps a lot”, which often means: too much. In industrialized countries, where a lot of nitrogen fertilizers are used, the amount can be significantly reduced with similar yields, according to a study by David Wüpper of ETH Zurich and his team in the specialized journal Nature Food.
Excess fertilizer does not benefit the plants, but it pollutes the environment. On the other hand, in many African countries, where farmers cannot afford fertilizer, more nutrients would significantly increase yields.