Context: Recently, the global phosphorus problem is gaining attention with limited phosphorus reserves, contamination issues, and disruptions in the fertilizer market.

• Phosphorus is a critical element for plant growth and is an essential component of fertilizers used in agriculture.

• However, there are several challenges associated with phosphorus use in agriculture, and hence finding sustainable solutions has become a critical priority.

Historical Evolution of Fertilization

• Fertilizing Land Through the Ages: Throughout agricultural history, sustaining fertile soil has been a persistent challenge. Early societies realized that continuous farming depleted nutrients, leading to decreased yields. They employed natural fertilizers like using fish remnants and bird droppings (guano) as fertilisers.

• Fertilizer Revolution: In the 19th century, chemistry breakthroughs birthed synthetic fertilizers and the discovery of vital nutrients like nitrogen, phosphorus, and potassium. These innovations laid the foundation for modern chemical fertilizers, boosting agricultural productivity.

• Green Revolution's Impact: The mid-20th century saw the Green Revolution, marked by high-yield crop varieties and intensive synthetic fertilizer use, ensuring global food production's sustainability.

Challenges Surrounding Phosphorus

• Phosphorus Scarcity and Pollution: Today, phosphorus, a key nutrient, is becoming scarce and causing environmental pollution. It doesn't exist as a gas, limiting its movement from land to water, where it triggers algal blooms and harms aquatic ecosystems.

• Limited Reserves and Cadmium Contamination: Phosphorus is scarce and primarily found in specific geological formations. This is a major geopolitical concern.The global phosphorus supply chain is dominated by a few countries, mainly Morocco and the Western Sahara, which hold the largest reserves.

• However, these reserves contain cadmium, a harmful heavy metal that can accumulate in human and animal kidneys. Removing cadmium from phosphorus is costly.

• Consequently, cadmium-laden fertilizers are used, leading to its absorption by crops and bioaccumulation in humans, potentially accelerating heart disease.

• Limited sources of cadmium-free phosphorus: The EU has enacted regulations to limit cadmium levels in fertilizers. Out of all the countries, only six have significant reserves of cadmium-free phosphorus.

• Among them, China imposed export restrictions in 2020, and several EU nations stopped purchasing from Russia, leading to a surge in demand for safe phosphorus.

• Sri Lanka's decision to ban synthetic fertilizers in 2021 resulted in a drop in crop yields and a political crisis.

• Phosphorus loss and pollution: Approximately only one-fifth of mined phosphorus is used for food production, with the rest being lost to water bodies through agricultural runoff due to excessive fertilizer use. This leads to environmental pollution.

• Sewage contamination: Most phosphorus consumed by people ends up in sewage. In India, much of the sewage is untreated or treated only at a basic level, resulting in the discharge of effluents containing nitrates and phosphates. While nitrates can be safely processed by denitrifying bacteria, phosphorus remains in water bodies, contributing to harmful algal blooms.

• These blooms deplete oxygen levels in the water, leading to fish deaths, and can also be toxic to humans, causing various health issues.

About Phosphorus

• Phosphorus is a chemical element with the symbol "P" and atomic number 15.

• It is an essential element for life and has various important properties and applications.

• Phosphorus readily forms compounds with other elements, especially oxygen, forming various phosphates.

• It is highly reactive and can spontaneously combust in air, producing a white smoke.

• Phosphorus compounds are crucial in biology, as they are a fundamental component of DNA, RNA, and ATP (adenosine triphosphate).

• Phosphorus is commonly found in the Earth's crust in the form of various phosphate minerals, such as apatite.

Phosphorus in India

• Phosphate rocks are also considered a significant and secondary resource of uranium.

• India is deficient in Apatite (group of phosphate minerals) & Rock Phosphate availability.

• According to Indian Minerals Yearbook 2018, in case of apatite, the country is fully dependent upon imports, while the Rock Phosphate production is only from two states namely, Rajasthan and Madhya Pradesh.

• India is the world's largest importer of phosphorus, primarily sourcing it from West African deposits contaminated with cadmium.

Potential Strategies for Managing Phosphorus Usage

• Precision Agriculture: There is a need to implement precision agriculture techniques to optimize the use of chemical fertilizers. This involves using technology like GPS-guided equipment and sensors to apply fertilizers only where and when they are needed, reducing over-application and nutrient runoff.

• Union Budget 2023–24 launched the PM-PRANAM scheme to promote the balanced use of chemical and alternative fertilizers, generating awareness of regenerative agriculture (RA).

• Phosphorus Recovery from Sewage: Investment should be made in technologies that extract phosphorus from urban sewage and wastewater treatment plants. This recovered phosphorus can be processed into high-quality fertilizers and used in agriculture, reducing the dependence on mined phosphorus.

• An innovative solution is emerging in the form of sludge-mining from STPs by companies like EasyMining in Europe. This approach recovers valuable nutrients from sewage, producing a high-quality fertilizer similar to conventional ones and making sewage treatment profitable.

• Source-Separating Toilets: There is a need to encourage the adoption of source-separating toilets that separate urine and feces. Urine is rich in phosphorus and can be collected and processed into a local fertilizer source.

• Circular Phosphorus Economy: There is a need to establish a circular economy for phosphorus, where products containing phosphorus are designed for easy recovery and recycling, reducing the need for mining and reducing environmental impact. 

Road Ahead

• Since much of the phosphorus is not actually taken up by crops, one way to ameliorate the phosphorus paucity is to reduce the use of chemical fertilisers through precision agriculture. 

• Mining phosphorus from sewage allows countries to control their own phosphorus production while also addressing the problem of water-body eutrophication.

• Innovators need to lower the costs of sewage mining to be financially viable in India; regulators need to allow the use of urban-mined phosphorus in agriculture; and Sewage treatment plants (STPs) need to be paid not based on discharge standards but on nutrient recovery.