Fertilisers feed the world

The demographic explosion that followed the Second World War brought another great battle to the 20th century: that of feeding Humanity. The exponential increase in agricultural production ensured that the world had access to food, but this was only possible because chemical fertilisers played a fundamental role in this process. 

Fertiliser is the food that plants need to grow and develop. Plants need light, carbon dioxide, water and nutrients such as nitrogen, phosphorus and potassium. But the soil can hardly provide all these elements in ideal quantities. And it is in order to fill this deficit that fertilisers gain strength, giving plants a better use of their resources.   

Man's first real contact with fertilisers goes back to the Neolithic period, twelve thousand years ago, when agriculture and livestock allowed prehistoric man to settle. 

Animal waste, vegetable debris, ash and clays were the first natural fertilisers used by man to fertilise the land, during the Neolithic Revolution or “Agricultural Revolution”, which took place in different places, such as the Middle East, Asia and Latin America, expanding all over the world. 

Throughout this period, prehistoric man settled. They developed agriculture, domesticated animals and plants, invented advanced metal utensils and established cultural and commercial exchanges with other groups. Thanks to a sedentary lifestyle, the population increased and the first cities or settlements emerged.

Farmers were dedicated to cultivating the land and the techniques of fertilising with ash and animal manure continued to flourish, becoming a kind of business in the region that comprised France, Belgium and Flanders, even during the Middle Ages. To compensate for the loss of nutrients in the soil, farmers also introduced fallow and crop rotation.

But the development of cities, with their enormous needs for food supply and the emergence of industry, has exponentially accelerated the consumption and dispersion of these nutrients from the soil, far beyond their capacity for regeneration.

Large-scale agricultural production and the abundance of current foods is only possible because a group of outstanding people in the 19th century - in demand for the Industrial Revolution and the consequent increase in the world population -, used chemical experiments to discover what affected the growth of vegetables. 

Contrary to the theories of the time, that plants absorbed organic substances resulting from the decomposition of animal bodies in the soil, the German chemist Justus Von Liebig (1803-1873) proved that plants need certain mineral elements to improve their growth. 

In 1840, Liebig shook the foundations of agricultural science in those days by defining the basic constitution of modern chemical fertilisers: nitrogen, phosphorus and potassium. The young alchemist, who spent most of his life in a chemistry lab, took about half a century to complete and present his work. He promoted heated debates on how to avoid hunger and provide the nutritional well-being of the population and today he is known as the “Father of the Fertiliser Industry”. 

Although the first fertiliser factory in the world appeared in 1843 in England, the great step in this area was taken again by Germany with several discoveries, such as the physicist-chemist Friedrich Ostwald (1853-1932). In his work, he discovered the process of preparing nitric acid from the oxidation  of ammonia, facilitating the mass production of fertilisers  and explosives.

Nitric acid is a chemical compound represented by the formula HNO3 used in the manufacture of fertilisers for agriculture. It is the second most manufactured and consumed acid in the industry, second only to sulphuric acid. In Portugal, nitric acid is produced exclusively by Bondalti, obtained from the catalytic oxidation of ammonia, according to the Ostwald Process. 

In the 20th century, the German chemist Fritz Haber discovered how to extract nitrogen from the air, synthesising ammonia and Karl Bosch perfected Haber's method for obtaining synthetic ammonia. The process of obtaining this method made it possible to synthesise almost all the ammonia necessary for the production of fertilisers. In addition, the fact that ammonia can be converted into compounds useful in the synthesis of explosives made its exploitation even more successful during the First World War. 

The universal use of chemical fertilisers has considerably increased food production worldwide. Today, it is unquestionable that fertilisers are essential for the survival of plants, animals and humans, providing food to a global population that is expected to reach nine billion before 2050. 

The great challenge of the 21st century will be to continue to improve the yield of agricultural land and at the same time to reduce the environmental impact of agriculture.