Nature and Production
Urea is a nitrogen-rich chemical compound with the formula CO(NH₂)₂. It is a white, crystalline and highly water-soluble substance containing about 46% nitrogen, the highest nitrogen concentration among commonly used solid fertilisers.
Commercial urea is produced by reacting ammonia with carbon dioxide under high temperature and pressure. Ammonia production usually depends on natural gas, making urea prices sensitive to global energy markets.
Apart from agriculture, urea is used in:
- chemical and resin manufacturing;
- animal feed in controlled quantities;
- pharmaceutical products;
- reduction of nitrogen oxide emissions from diesel engines.
Agricultural Importance
Nitrogen is essential for plant growth because it supports the formation of chlorophyll, proteins and enzymes.
Urea is widely used to improve:
- vegetative growth;
- leaf development;
- crop yield;
- protein content in certain crops.
After application to soil, urea is converted into ammonium and later into nitrate, which plants can absorb.
Its effectiveness depends on correct timing, placement, moisture and quantity. Surface application without incorporation may lead to loss of nitrogen as ammonia gas.
Excessive application can produce rapid leafy growth without a proportional increase in grain or fruit yield.
Environmental Effects
Only a portion of the nitrogen applied through urea is absorbed by crops. The remaining nitrogen may be lost through:
- ammonia volatilisation;
- nitrate leaching into groundwater;
- surface runoff;
- emission of nitrous oxide;
- accumulation of excess nitrogen in soil and water.
Overuse can cause:
- soil nutrient imbalance;
- groundwater contamination;
- eutrophication of water bodies;
- air pollution;
- increased greenhouse gas emissions;
- decline in long-term soil health.
Urea use must therefore be balanced with phosphorus, potassium, micronutrients and organic matter according to soil requirements.
Urea Policy in India
Urea is an essential and heavily subsidised fertiliser in India. It is sold to farmers at a government-controlled maximum retail price, while the difference between the production or import cost and the retail realisation is paid as subsidy.
Unlike phosphatic and potassic fertilisers, urea is not governed by the Nutrient Based Subsidy system. Its low controlled price compared with other fertilisers has encouraged excessive and imbalanced nitrogen use.
Important policy measures include:
- mandatory neem coating of domestically produced and imported agricultural urea;
- Direct Benefit Transfer-based recording of retail sales;
- revival and expansion of domestic urea plants;
- promotion of soil testing and balanced nutrient application;
- introduction of smaller bags and alternative fertiliser products;
- promotion of nano urea and organic nutrient sources.
Neem-coated urea slows the conversion and loss of nitrogen, improves nutrient-use efficiency and reduces diversion of subsidised urea for industrial purposes.
Challenges and Sustainable Use
Major concerns include:
- excessive application due to low prices;
- imbalance in the nitrogen–phosphorus–potassium ratio;
- dependence on imported natural gas and urea;
- large fiscal burden of fertiliser subsidy;
- diversion for non-agricultural use;
- regional shortages during peak sowing seasons;
- environmental damage from inefficient nitrogen use.
Better management requires:
- soil-test-based application;
- split doses at appropriate crop stages;
- placement of fertiliser near plant roots;
- use of precision-farming techniques;
- greater use of legumes, compost and biofertilisers;
- improvement in irrigation practices;
- gradual correction of distorted fertiliser prices;
- direct support to farmers instead of encouraging excessive product use.
Conclusion
Urea is indispensable to Indian agriculture because of its high nitrogen content and affordability. However, excessive and inefficient application damages soil, water and climate. Agricultural policy must therefore shift from maximising fertiliser consumption to improving nutrient-use efficiency and balanced soil nutrition.
