Issues associated with disposal of Phosphorus in India
Introduction:
- Fertilisation of the land has been an issue for as long as there has been agriculture. Early humans who first engaged in settled agriculture soon understood that while crops needed minerals for growth, frequent cycles of cultivation and harvest depleted these nutrients over time, lowering production.
The modified procedures:
- The practises to replenish the vital nutrients in the soil required for plant and agricultural growth were inspired by this insight.
- Indigenous peoples all around the world have created fertilisation techniques, such as employing guano and fish waste as fertilisers.
- This began to change in the 19th century, when chemistry made tremendous strides that enabled the development of synthetic fertilisers and the identification of nitrogen, phosphorous, and potassium.
- High-yield crop varieties and intense usage of these fertilisers were hastened by the Green Revolution of the middle of the 20th century, and these ingredients are now essential to maintaining global food production.
Concerns regarding phosphorus:
- Phosphorus is rare and only occurs in trace amounts in some types of geological formations.
- It pollutes the environment in addition to being scarce.
- Since it cannot exist as a gas, it can only migrate from land to water, where it causes eutrophication and algae blooms.
phosphorus and global politics:
- The discovery of phosphorus in guano and its subsequent global supply chains are both part of its history.
- Morocco and the Western Sahara region contain the bulk of the world’s reserves.
- However, cadmium, a heavy metal that can build up in the kidneys of both humans and animals when consumed, coexists here with phosphorus.
- Cadmium removal is also a pricey procedure.
- Because of this, cadmium-containing fertilisers are frequently applied to the soil, ingested by crops, and bioaccumulated in human bodies.
- According to studies, this quickens heart disease.
- There are just six nations with sizable phosphorous supplies free of cadmium.
- 2020 saw China curtail exports, while many EU nations stopped purchasing from Russia. As a result, the demand for safe phosphorous has unexpectedly skyrocketed.
- This is one of the reasons Sri Lanka prohibited the import of synthetic fertilisers in 2021 and switched to organic farming, which was followed by a sharp decline in agricultural productivity that sparked a political crisis.
- India currently imports the most phosphorus in the world, the majority of it coming from West African mines that are high in cadmium.
- Although not all plants absorb cadmium at the same rate, Indian farmers frequently fertilise their key crop, paddy, making it particularly vulnerable.
- Cadmium is also absorbed by other grains like wheat, barley, and maize, but less so.
The issue with phosphorus disposal
- First off, only around 5% of the phosphorus that is mined is really used in food. Due to the overuse of fertilisers, a large portion of it is lost directly to water sources as agricultural runoff.
- Second, the majority of phosphorus consumed by people is excreted in sewage. In India, the majority of sewage is still untreated or simply gets secondary treatment.
- Therefore, the effluent discharged from STPs still contains nitrates and phosphates long after the organic stuff has been digested.
- In contrast to phosphorus, which is retained in the sediments and water column, nitrates can be safely released as nitrogen gas into the atmosphere after being digested by denitrifying bacteria.
- The increased nutrient supply causes algal blooms to form, which absorb it. As they break down, microorganisms that feed on them devour the dissolved oxygen.
- As a result, fish start to perish in oxygen-starved water. In addition to being hazardous, the algal blooms can make humans sick with respiratory problems, nausea, and other conditions.
Locating phosphorous somewhere else:
- Precision agriculture can help alleviate the phosphorus shortage by reducing the usage of chemical fertilisers because a large portion of phosphorus is not really absorbed by crops.
- Low-input agro-ecological methods are demonstrating themselves to be a strong substitute.
- However, there is growing interest in using urban sewage mining to produce high quality phosphorus, thus closing the phosphorous loop.
- Since the European Union has essentially no phosphorus reserves of its own, interest in “circular water economies” has forced it to reconsider the urban water cycle.
- First, use toilets with source-separated bowls because the majority of the phosphorus we eat ends up in our pee and the remainder in our faeces.
- Potassium and nitrogen are also abundant in urine. We could create a local source of fertiliser if we can gather this concentrated, safe waste stream.
- Second, recycling sewage and sludge – Sewage recycling is already practised in India in some capacity.
Way ahead:
- The best course of action is to establish a circular water economy. Can we grant a concession to put up STPs with phosphorus mining operations and allow them to sell the fertiliser if the technology is sufficiently affordable?
- India might benefit from these improvements by becoming less dependent on hazy geopolitical crises, allowing farmers to buy fertiliser at reasonable prices, giving water bodies some possibility of becoming swimmable, and improving public health by consuming food cultivated in cadmium-free soils.
