Nitrogen in crop production - Tough to curb liability

摘要

The discovery of synthesis of ammonia by Fritz Haber (1915) for which he was awarded the Nobel Prize in chemistry was the starter of N fertilizers all over the world. Today India claims the pride of place among the top three, China, USA and India, for production and consumption of fertilizers in general and nitrogen, in particular. Yet crop yields of the three major cereals of India by 1998-99, wheat, rice and maize, were only 65, 46 and 35 percent, respectively of those in China. The remarkable success in 'yield revolution' in India, where the fertilizer was the lynchpin reached a climax by 1984, but remained so only for a few years as yield fatigue had set in by 1990 and has since continued despite increasing use of fertilizers. The tropics (India) are an area of vast climatic potential for plant growth and agriculture (multiple cropping), but there is over-exploitation and mismanagement of nitrogen fertilizers through five practices, viz. increasing levels season after season, widening N: P ratio, absence of blending with organics, insisting basal application, and broadcast prilted form of urea. Such abuse continued to hedge out the entry of use efficiency. Human interference of alteration of the N-cycle has grave consequences such as nitrate pollution of underground water, bluebaby syndrome, eutrophication of aquatic systems, a threat to sustainability of fish. Also, pollutants produce petrochemical smog which gives rise to respiratory problems. A host of environmental problems, including global warming, acid rain and loss in biodiversity are enough threats to challenge us for a long time. Where added, N increases the productivity of the ecosystem and it also decreases their biological activity4.