Urea
Urea waste product formed in the mammalian liver when nitrogen compounds are broken down. It is excreted in urine. When purified it is a white, crystalline solid. Urea is transported in the blood to the kidneys where it is filtered out; its concentration in urine is about 60 to 70 times as great as in blood. In industry it is used to make urea formaldehyde plastics, pharmaceuticals and fertilisers. In 1773 it was noted that urea gives off ammonia when heated. This knowledge provided a clue to its structure. Later, in 1828 the artificial formation of urea from ammonia and cyanic acid was discovered. Urea became the world';s leading N-fertiliser in the mid-1970s.
Urea fertiliser is used in Bangladesh as a major nitrogen (N) source for rice cultivation. Of the total nutrients used in the country, nitrogen alone constitutes about 80 percent. About 9,42,771 tons of nutrient N alone were used in 1995-1996, out of total 11,79,3910 tons of nitrogen, phosphorus (P), potassium (K), sulphur (S), and zinc (Zn) nutrients
With substantial natural gas reserves, Bangladesh is well placed to convert this resource to fertiliser for agricultural development. Six urea fertiliser factories sponsored by BCIC are currently operating. They are NGFF, Fenchuganj; UFFL, Ghorashal; ZFCL, Ashuganj; Palash, Ghorashal; CUFL, Chittagong and Sarishabari (Jamuna), Jamalpur. These factories produced about 1.6 million tons of urea in 1996-1997, which provided about 75% of the total consumption. The Jamuna Fertiliser Factory produces good quality pea-sized granular urea, which is most suitable for rice cultivation. Another private sector fertiliser factory named kafco situated on the left bank of the karnafuli river near Patenga in Chittagong is now also operating.
The Government of Bangladesh has undertaken plans to popularize the Urea Deep Placement (UDP), a technology that doubles the efficiency of urea fertilizer use. UDP is the insertion of large urea briquettes into the rice root zone after transplanting. The effectiveness of the technology in Bangladesh was proven through research funded by the International Fund for Agricultural Development (IFAD) and implemented with the assistance of IFDC (International Center for Soil Fertility and Agricultural Development).
Using UDP, Bangladesh';s dry season rice production is expected to increase by 548,000 tons, according to the Department of Agricultural Extension (DAE). UDP technology improves nitrogen use efficiency by keeping most of the urea nitrogen in the soil close to the rice roots and out of the floodwater, where it is more susceptible to loss as gaseous compounds or runoff.
The technology not only improves farmer';s income, but also creates employment for manufacturing briquettes. Ten Bangladeshi manufacturers have produced and sold more than 2,000 briquette-making machines. The new UDP program will include the manufacture and establishment of some 300 briquetting machines to manufacture 2.7-gram briquettes.
UDP technology was introduced in Bangladesh in the late 1990s; by 2006 more than half a million farmers had adopted UDP. Average paddy yields had increased 20% to 25%, and income from paddy sales increased by 10%, while urea expenditures has decreased 32%. Farmers who use UDP can reduce urea use by 78 to 150 kg/ha and increase paddy yields by 900 to 1,100 kg/ha. The net return to farmers of using UDP versus broadcasting urea averages $188/ha. Bangladesh';s success with UDP has become a model for other rice-growing countries. IFDC has also introduced UDP technology in Cambodia, Vietnam, Nepal, Nigeria, Mali, Togo, and Malawi. [Md Akhter Hossain Khan] [Khan, Md Akhter Hossain Professor of Soil, Water and Environment, Dhaka University]
