Introduction

In the sprawling world of modern agriculture, there exists often an overlooked but vital ingredient for food production: Chemical fertilizers. These unassuming substances possess an unparalleled power to shape the destiny of nations, determine the fates of millions, and hold the delicate balance of ecosystems in their granular grasp. Like silent sentinels, they stand as the unsung heroes of India's agricultural revolution, enabling bountiful harvests from vast swathes of land, ushering the Benefits of fertilizers upon which our survival hinges. Their story is one of innovation, of ingenuity, and a relentless pursuit of higher yields in an ever-hungry world.

Background

It is widely believed that ancient civilizations like Mesopotamia and Egypt were the first to discover the transformative properties of manure and compost. The very first formulation of Chemical fertilizers is generally attributed to German chemist Justus von Liebig. In 1910 and 1920s the Haber and Ostwald process was invented and subsequently utilized for fertilizer production. In India, the first superphosphate plant was established at Ranipet ( Tamil Nadu). Thereafter  Fertilizers and Chemicals Travancore ( FACT) in Kerala and Fertilizer Corporation of India in Sindhri ( Jharkhand) were established. The Green Revolution in India in the late 60s spurred significant investment in this sector from Public, Private, and Co- cooperative, entities, driven by favorable government policies. The last 50 years have seen a tremendous upswing in fertilizer consumption as the Benefits of fertilizers became evident. The table below provides details of fertilizer consumption in India:
  Fertilizer Consumption (Courtesy : FertiliserIndia.com)

Urea-based fertilizers exhibit the highest usage and are anticipated to grow at 4.7% CAGR.  We are nearing self-sufficiency in urea production, with projections indicating that we will cease imports by the end of 2025. This aligns with the government policy of Atmanirbhar Bharat ( Self Sufficiency). The process of manufacture of Urea is briefly outlined  below:

Urea Manufacturing Process
  Urea Manufacturing process (Courtesy : chemicalenginneringworld.com)

Urea is an organic chemical compound, also referred to as Carbamide. Commonly available as prills or granules, they are highly soluble in water and can be easily diluted to the required concentration.  With a nitrogen content of 46%, it boasts a high nutrient value. Please refer to the illustration above. Liquid ammonia(NH3) and Carbon dioxide are transported to a Synthesis tower. To initiate the first reaction, the pressure and temperatures are nearly maintained at 14Mpa and 170 to 190 deg C. The reaction is highly exothermic. The heat released is in the form of process steam and can be utilized elsewhere in the process. The Ammonium Carbomate produced is led into a distillation tower, where it decomposes to form urea and water in an endothermic reaction. Unreacted materials are recycled as depicted in the figure. The resulting product is subsequently led into an evaporator for concentration, done at an optimum temperature to prevent crystallization. It is then fed into a prilling tower, where it encounters compressed air in a counter-flow current. The urea gets solidified and the air helps in shaping it in the form of prills or granules. This final product is packed into bags for distribution.

Sometimes the prills are coated with neem oil, which preserves the nitrogen component. It slows down the release of nitrogen, thereby reducing the urea requirement. This indirectly also saves on fertilizer subsidies. Urea is an inexpensive form of Synthetic fertilizer and is produced in large quantities.

Major Players

Being a dynamic sector, it is marked by mergers and acquisitions, expansion, and investment plans. Growth is projected is 4.7% CAGR between 2024 and 2032, driven by increasing demand for food due to population growth, limited land availability, and higher disposable incomes.  Key players in the Indian Fertilizer market include Coromandel International Ltd, Chambal Fertilizers and Chemicals Ltd, Gujarat Narmada Fertilizers and Chemicals Ltd, Indian Farmers Fertilizer Co-operative Ltd (IFFCO), and Rama Phosphates Ltd.

Additionally, United Phosphorous Ltd ( UPL) is an Indian multinational company that manufactures and markets agrochemicals and various chemical products.

A  portion of the urea produced is also used in urea-formaldehyde resins for wood-based panels such as plywood, particle board, and fibreboard. Other minor usages are for explosives, animal feed, etc.

Recently there has been considerable interest shown in the  IFFCO nano urea spraying scheme. Here drones are employed in spraying nano urea over crops. This method proves to be more effective than other Fertilizer application techniques.
  Drone spraying liquid urea over a wheat field. (Courtesy : Adobe Firefly)

Envoirmental Impact

Only a fraction of the nitrogen-based fertilizer applied is converted to plant matter, with the remainder accumulating in the soil. Some of this is lost as runoff water through irrigation or rainfall. Urea being water soluble,  leaches into groundwater causing pollution. If nitrate levels are over 10mg/L, it can result in  "blue baby syndrome".

Agricultural runoff can also lead to Eutrophication, where algae and other aquatic plants can flourish with the help of the nutrients, forming dense mats on the water surface called algal blooms. They block sunlight from reaching underwater plants and also deplete oxygen levels as they decay. This leads to hypoxic or anoxic  ( low or no oxygen) conditions, which harm or kill aquatic life. Fisheries, water quality, and bio-diversity are affected.

Yet another Environmental effect of fertilizers is the increase in soil acidity, as urea-based fertilizers release hydrogen ions. This leads to a decrease in nutrient availability, necessitating the addition of lime to the soil to bring back pH levels to acceptable limits.

Conclusion

From their humble origins in the dawn of civilization to their pivotal role in shaping the modern world, fertilizers stand as a symbol of humanity's unyielding drive towards sustenance and prosperity. However, it is not devoid of complexity and consequence. We have witnessed the fruits of this labor reaped in abundance, but have also witnessed the toll exacted upon our fragile ecosystems. In the delicate balance between progress and preservation,  fertilizers occupy a pivotal space, one where the imperatives of food security must be balanced with the imperatives of environmental sustainability.  It is a challenge that demands both innovation and enlightened stewardship and a steadfast commitment to both present and future generations.