Living on air On the importance of nitrogen for our nutrition PRINT VERSION
Living on air I 1 CONTENTS It’s impossible to “live on air,” naturally Introduction Why do we need to add nitrogen? Why do we need to add fertilizers? Living on air Growing with nitrogen From air to plant nutrient Producing nutrient nitrogen From nutrient back to air Loss of nutrient nitrogen Keeping the nitrogen cycle in balance with supplementary nitrogen Pulled out of thin air Adding nutrient nitrogen Nutrient nitrogen no longer comes only from natural sources Ready for the future 19 9 11 13 15 7 3
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Living on air It’s impossible to “live on air,” naturally And yet, there’s a lot of truth in this saying. Our atmosphere supplies us with oxygen, water and nutrients. The Netherlands plays an important role in global food security. Thanks to our expertise and efficient farming methods, we’re able to achieve high crop yields while maintaining the long-term fertility of our soil. The key factor is optimal fertilization: organic manure as the basis, supplemented by the smart use of mineral fertilizers. • Mineral fertilizers are responsible for feeding almost half of the people on Earth. • The world population currently stands at seven billion and is growing by 200,000 people a day. • A world without fertilizers would be able to feed about four billion people. Why do we need to add nitrogen? Nitrogen is vital for all life on Earth. It forms the basis for our DNA and proteins and is a natural component of the air that we breathe. But to make nitrogen suitable for consumption, it needs to be converted into a “fixed” form called nutrient nitrogen. Plants use nutrient nitrogen to make proteins that serve as food for animals and people. After fixation, some of the nutrient nitrogen is lost again in the complex process of nitrogen utilization and consumption. That loss is natural and unavoidable and makes it necessary to replenish nitrogen in the soil. That is where fertilizers come in. I 3
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Living on air I 5 Why do we need to add fertilizers? To keep their soil fertile, farmers start by adding organic manure, including animal dung and compost. Recycling the valuable elements contained in dung and compost is both sensible and necessary, but they don’t provide enough nutrient nitrogen to compensate for unavoidable losses. Fertilizer can make up the difference. Every soil type requires a different approach to fertilization. Because mineral fertilizers can be tailored to the soil’s and plant’s specific nutrient requirements, loss to the environment – and thus environmental impact – is minimized. Mineral fertilizers also have an immediate and predictable effect. Combining different fertilizers improves soil productivity and maintains healthy soil. Recent research by Prof. Jaap Schröder at Wageningen University & Research Centre focused on smart fertilizer use. His advice: “Use it where and when necessary.” He explains how mineral fertilizers contribute to healthy farmland and allow us to grow a sufficient amount of nutritious food. Below are some of his conclusions: Fertilizers: • are necessary to meet the growing demand for food • improve the quality of farmland • are part of a sustainable food chain • provide a necessary and efficient supplement to organic fertilizers • are a responsible source of nutrient nitrogen “Living on air” is an easy-to-read essay describing the route that nitrogen takes from air, rain and soil to our breakfast table.
6 ,, We are creatures of the air. Thomas Hager, writer and science historian, 2008 ,,
Living on air I 7 Living on air Growing with nitrogen “We are creatures of the air. The stuff of our bodies – the atoms that make up our skin and bone, blood, brain, and everything else – comes primarily from the atmosphere. Sometimes the route is direct, sometimes indirect.” The above quote, taken from Thomas Hager’s The Alchemy of Air, links air to life. Our bodies and our minds basically consist of chemical bonds between different elements. We take many of these elements from the air that we breathe. We all know about oxygen, hydrogen and carbon, which we take in by breathing, drinking water and eating carbohydrates. We also know about calcium and iron, which we consume in dairy products and vegetables, and sometimes by taking supplements. But what people often do not know is that we carry about two to three kilos of nitrogen around in our bodies. Nitrogen, the chemical element N, forms the basis for our DNA and proteins. During cell replacement, proteins are broken down and leave our body. Because we have only limited reserves of nitrogen and proteins in our bodies, we need to supplement them daily. Plants also contain proteins and need nitrogen to grow. Nitrogen is one of the foundations of all life on Earth. Without nitrogen, there is no life.
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Living on air From air to plant nutrient Producing nutrient nitrogen We are surrounded by an endless amount of nitrogen. Almost 80% of the Earth’s atmosphere is made of gaseous nitrogen, known as atmospheric nitrogen or N2. We breathe it in, but our bodies cannot absorb it. It’s as if we were bobbing around in a boat on an immeasurable ocean, surrounded by an endless amount of water that we’re unable to drink. To make atmospheric nitrogen suitable for consumption, it has to be “fixed.” The process of fixation produces nutrient nitrogen, which serves as a plant nutrient. In nature, nitrogen is fixed both in the atmosphere and in the soil. Lightning strikes, for example, will cause some fixation of atmospheric nitrogen, with rain then carrying the result, nutrient nitrogen, to the soil. When bacteria in the soil work together with certain plants, especially clover, they also fix atmospheric nitrogen. Once again, the resulting nutrient nitrogen ends up in the soil. Plants absorb this nitrogen and use it to synthesize proteins and other substances, making it available to animals and people who eat the plants. I 9
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Living on air From nutrient back to air Loss of nutrient nitrogen In farming, most of the nutrient nitrogen is lost during harvest. Protein-rich – and therefore nitrogen-rich – plants are simply removed from the land. Farmers obviously need to replace the nutrient nitrogen they have removed in order to restore the fertility of the soil. That is not enough, however. Besides the nutrient nitrogen “lost” to the harvest, nitrogen is also lost to the air and soil in natural processes. Although the soil contains bacteria that convert atmospheric nitrogen into nutrient nitrogen, bacteria that do precisely the opposite are even more common. They convert the nitrogen back into a gas that evaporates into the air, so that it is once more unavailable for plant growth. Nutrient nitrogen that plants can absorb is mobile. The portion that the plant has not yet absorbed can be flushed away into the soil in heavy rain. Depending on the circumstances, part of it will leach from the soil into the ground water and surface water. The loss of valuable nutrient nitrogen is both natural and unavoidable. The nature and scale of nitrogen loss depend on the climate, the weather, the type of crop, the type of soil, and the degree of fertilization efficiency. The scale of the loss is roughly comparable to the amount of nitrogen contained in the crops removed in the harvest. I 11
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Living on air I 13 Keeping the nitrogen cycle in balance with supplementary nitrogen N Almost 80% of the Earth’s atmosphere is made of gaseous or atmospheric nitrogen. To make atmospheric nitrogen suitable for consumption, it has to be “fixed.” In nature, nitrogen fixation takes place in the atmosphere and in the soil. Atmospheric nitrogen can be fixed in the atmosphere by lightning strikes, for example. Rain then carries it to the soil in the form of nutrient nitrogen. In the soil, bacteria fix atmospheric nitrogen. N Nutrient nitrogen disappears when crops are removed from the land. In addition, natural processes cause it to disappear into the air, soil and water. To meet the world’s growing demand for food, early twentieth-century scientists developed a method for producing nutrient nitrogen. The fixation of atmospheric nitrogen now occurs on an industrial scale, with mineral fertilizers as the product. Together with the nutrient nitrogen produced by natural fixation in the atmosphere and soil, they make an unbeatable combination.
14 ,, Water, water, everywhere nor any drop to drink ,, Samuel Taylor Coleridge, English poet, 1798
Living on air I 15 Pulled out of thin air Adding nutrient nitrogen Let’s go back to our little boat bobbing around on the ocean. We’re surrounded by an endless amount of water, and yet we’re thirsty. Our water bottle is empty. Fortunately it starts to rain – but not enough to fill our bottle. We have to come up with something clever. The same is true of nitrogen. We are surrounded by it, and yet we cannot consume it. To do that, we first have to convert it to nutrient nitrogen. The amount of nutrient nitrogen available in natural sources (lightning strikes, soil bacteria) has always been small, but until quite recently it was enough to feed the world population. That was largely thanks to farmers, who are preeminent nitrogen experts. Intent on improving their crops and increasing their harvests, farmers started using nutrient nitrogen many centuries ago, in the form of bird droppings, farmyard dung, and compost. They also let fields lie fallow to “save up” nutrient nitrogen.
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Living on air I 17 Nutrient nitrogen no longer comes only from natural sources By the end of the eighteenth century, population growth had led to a shortage of nutrient nitrogen. There simply wasn’t enough to meet the rising global demand for food. In the second half of the nineteenth century, guano – the dried excrement of seabirds – became popular worldwide as an extra source of nutrient nitrogen. It could not solve the manure shortage problem, however. It was time for a bit of cleverness. In the early twentieth century, two researchers came up with the eponymous Haber-Bosch process for the mineral fixation of atmospheric nitrogen. This innovation is still regarded as one of the greatest inventions of all time. The Haber-Bosch process fixes atmospheric nitrogen on an industrial scale with hydrogen obtained from natural gas or electricity. The nutrient nitrogen it produces is used as plant nutrition in the form of mineral fertilizer.
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Living on air I 19 Ready for the future A hundred years have passed and we now share our world with more than seven billion people. According to forecasts, the Earth’s nine billionth inhabitant will be born in 2050. Our food production cannot lag behind population growth. If we depended solely on the nutrient nitrogen produced by lightning strikes and soil bacteria, our Earth would only be able to support four billion people. Much of our diet would be vegetarian and we would have to take a considerable amount of farmland out of production every year so that we could save up nutrient nitrogen by growing clover. The natural world would suffer because we would need to reclaim much more land for farming. Fertilizers are therefore inevitable in our day and age. In theory, we can produce an endless amount of nutrient nitrogen. However, we need to be economical in our use. Nitrogen fixation takes a lot of energy, and excessive use of nutrient nitrogen would be harmful to the environment. Today’s efficient farming methods allow us to achieve high crop yields while maintaining the long-term fertility of our soil. The key factor in all this is optimal fertilization: organic manure as the basis, supplemented by the smart use of mineral fertilizers. Mineral fertilizers help plants to absorb nitrogen efficiently, and organic manure ensures that nutrient nitrogen is properly recycled. It’s an unbeatable combination. Adding nutrient nitrogen is both efficient and economical. It makes perfect sense.
20 About this publication Publisher OCI Nitrogen B.V. Mijnweg 1 6167 AC Geleen The Netherlands tel. + 31 46 7020111 www.ocinitrogen.com Editors Elisabeth Koot, Jan Jaap Nusselder Translation Balance, Amsterdam/Maastricht Sources Schröder, J.J. (2014) The Position of Mineral Nitrogen Fertilizer in Efficient Use of Nitrogen and Land: A Review. Natural Resources, 5, 936-948 Hager, T. (2008) The Alchemy of Air, Harmony/Crown Food and Agriculture Organization of the United Nations (FAO) Fertilizers Europe (represents the largest fertilizer manufacturers in Europe) Postbus 601 6160 AP Geleen Disclaimer OCI Nitrogen is making the data in this publication available for information purposes only. Although the data has been compiled to the best of its knowledge and is based on recent information, OCI Nitrogen accepts no liability in this connection. Although OCI Nitrogen has reviewed the accuracy and completeness of the data and information provided in this publication with the greatest possible care, it does not guarantee that they are without error or flaws. OCI Nitrogen accepts no responsibility whatsoever for any damage that may arise owing to the use, incompleteness or inaccuracy of the information offered in this publication. No rights may be derived from the information in this publication. The copyright in this publication rests with OCI Nitrogen or third parties who have consented to make material or images available to OCI Nitrogen. Third parties are prohibited from disclosing or reproducing any part of this publication without the prior consent of OCI Nitrogen. © 2015 OCI Nitrogen B.V.
Climate change and a rapidly growing population are putting world food production under pressure and exhausting the Earth’s resources. Sustainable food production and corporate social responsibility are needed to safeguard the world’s future. The solution is to fertilize existing farmland by sustainable means. Mineral fertilizers are an essential part of this, with health and the environment being the top priority. In the knowledge that mineral fertilizers play an important role in society, OCI Nitrogen continuously invests in research and technology. We are eager to share our expertise and research results, not for commercial purposes but motivated by our commitment to sustainability. For the digital version of this publication, see www.livingonair.nl PRINT VERSION
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