Apart from economics, nitrogen loss has serious social implications. The unused fertiliser nitrogen either leaches down the soil bed or enters the atmosphere as gases. Fertiliser nitrogen which leaches down contributes to nitrate pollution of the groundwater. A high nitrate ground water, when used for drinking causes methemoglobinemia, a condition which incapacitates blood haemoglobin to carry oxygen to body cells. Infants are more prone to methemoglobinemia than adults. Fertiliser- Nitrogen which enters the atmosphere in gaseous forms mainly comprises ammonia, nitrous oxide and nitric oxide. Saturation of environment with these gases causes destruction of stratospheric ozone layer exposing the biosphere to harmful ultraviolet radiation.

Minimising nitrogen loss is a basic step to prevent atmosphere and groundwater pollution besides saving in the fertiliser cost to the farmers. Indian Agricultural Research Institute has developed a method to inhibit this natural process of nitrogen transformation in paddy fields using encapsulated calcium carbide (ECC) grains alongwith nitrogenous fertilisers.

This new technology reduces nitrogen loss considerable, and increases the yield. This nitrification inhibitor is cheap, easy-to-produce and easy-to-use. The process is essentially based on use of calcium carbide grains of 2 to 4 mm size encapsulated with 10 to 15 percent alcoholic solution of shellac, paraffin wax, petroleum jelly and clay. ECC reacts with moisture in the soil to produce acetylene at a very slow rate which effectively inhabits oxidation and the inhibitory effect remains for about eight to ten weeks even after all the measurable traces of acetylene vanish from the soil.

Acetylene stops both nitrification and denitrification processes, saves the loss of fertiliser nitrogen and also completely eliminates the generation of greenhouse gases from paddy fields under submerged condition.

It has been observed that this technology prevents the loss of 30 to 40 percent of fertiliser nitrogen and thereby helps increase crop production. Some field experiments with ECC were carried out in India, USA and Australia between 1988 and 1992 on paddy and cotton. The rice grain yield increased by 15 to 25 percent and lint cotton increased by 20% with use of ECC with urea, as compared to fields where urea alone was used. It has been estimated from the field data that application of this technology, results in an increase in net profit of Rs. 25,000/ per hectare.Comparative field studies with different types of nitrification inhibitors were conducted and it was observed that ECC is the most effective nitrification inhibitor, as this works efficiently in all types of soil and under all moisture regimes. This technology has also proved to be very effective in checking the environmental pollution from methane and carbon-di-oxide emission from submerged rice fields.

PROCESS

Calcium carbide grains of 2 to 4 mm size are coated twice with alcoholic solution of lac. These grains are dried at a temperature of 65⁰C in a closed system. About 85% of used alcohol can be recovered from the coated material . These grains are further treated with molten paraffin wax and petroleum jelly and finally with soap stone powder.