Urea is a white, granular chemical commonly used in agriculture to supply nitrogen, and it is the most widely used nitrogen fertiliser. Urea contains 46 per cent nitrogen; it is a high-nitrogen fertiliser, meaning 100 kg of urea holds about 46 kg of nitrogen. A popular nitrogen-based chemical fertiliser, it helps crops grow quickly. But although it is used widely in farming, excessive or uncontrolled use poses a major threat to the environment.

On domestic production and import dependence, the article says Bangladesh uses 2.6-2.7 metric tonnes of urea every year, of which only about 0.5 metric tonnes is produced in the country, and the remaining roughly 80 per cent (1.66 metric tonnes) depends on imports. At current prices its economic value is about Tk 44,000-45,000 crore. The environmental effects of urea are explained below.

Soil degradation: urea is high in nitrogen, which builds up in the soil and changes its pH. Excessive urea reduces the soil's organic matter and harms microbial biodiversity. In the long run the soil hardens and fertility falls.

Crop damage: using too much urea is harmful. Insect attacks increase, disease rises and, finally, yields fall.

Water pollution: excess urea is washed by rain into rivers and canals or into groundwater. This raises nitrate levels in the water, which is harmful to aquatic life and a risk to human health. In children especially, it can cause "blue baby syndrome" or methaemoglobinaemia.

Air pollution and climate change: nitrogen in urea reacts with the soil to form nitrous oxide (N2O), a powerful greenhouse gas that can trap about 300 times more heat than carbon dioxide. Released into the air, it plays an important role in global warming and climate change.

Harm to aquatic life: when water holds too much nitrogen, algae grow rapidly, causing eutrophication. Water bodies then run short of oxygen and fish and other aquatic animals can die. Fish stocks decline and aquatic ecosystems are disrupted.

Obstacle to organic farming: dependence on urea draws farmers away from organic farming. The land's natural ability to build fertility declines and reliance on fertiliser grows, which stands in the way of sustainable agriculture.

What should be done: balanced fertiliser management should be followed when using urea. The use of organic fertiliser, compost and vermicompost must be increased. Urea should be applied only as needed, after testing the soil. Farmers need training in environment-friendly farming methods. Overuse of urea can damage soil quality, harm plants or reduce yields, and urea can quickly lose nitrogen on contact with water.

Benefits: in moderate amounts, urea helps plants form green leaves and grow. It helps make chlorophyll, through which plants make food. It raises crop yield and quality, works quickly and mixes easily into the soil. Applied at the right dose and at the right time as needed, it is very beneficial for crops.

Although urea gives an immediate boost to crop production, in the long run it seriously affects soil, water, air and biodiversity. For sustainable agriculture and environmental protection, proper control of urea use and the adoption of alternative environment-friendly methods are now essential.

Source: Jagonews24. First published in Bengali on The Agro News.