Limited Phosphorus Resources: Does The Solution Lie In Our Sewage?

Relevance: GS3 - Agriculture; Transport and marketing of agricultural produce and issues and related constraints; Food Security

(Source: The Hindu, 09/27/2023)

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Why in the news?

• 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.

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.

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FAQs

MCQ

Question: Consider the following organisms: (UPSC 2013)

1. Agaricus
2. Nostoc
3. Spirogyra

Which of the above is/are used as biofertilizer/ biofertilizers?

(a) 1 and 2 only

(b) 2 only

(c) 2 and 3 only

(d) 3 only

Question: With reference to chemical fertilizers in India, consider the following statements: (UPSC 2020)

1. At present, the retail price of chemical fertilizers is market-driven and not administered by the Government.
2. Ammonia, which is an input of urea, is produced from natural gas.
3. Sulphur, which is a raw material for phosphoric acid fertilizer, is a by-product of oil refineries.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 and 3 only

(c) 2 only

(d) 1, 2 and 3