Some compounds added to nitrogen (N) fertilizers can reduce the rate at which ammonium is converted to nitrate. This will certainly reduce the loss of Nitrogen created in soil due to leaching and denitrification.
The rate of nitrification can be controlled by preserving N as ammonium, which can be held on soil colloids rather than leached. Nitrification inhibitors are compounds that delay nitrate production by depressing the activity of Nitrosomonas bacteria. In the market, Nitrogen inhibitors are generally available in 8 different products but the most commonly used are 2-chloro-6-(trichloromethyl)-pyridine (Nitrapyrin), dicyandiamide (DCD) and 3, 4-dimethylpyrazole phosphate (DMPP). These compounds can be used depending on the soil moisture and soil type but mostly they suppress microbial activity. They are mostly applied to sandy soil or soil low in organic matter and exposed to low temperatures.
Dicyandiamide (DCD) and 3, 4-dimethypyrazole phosphate (DMPP) are often claimed to be efficient in regulating soil N transformations and influencing plant productivity, but the difference of the cost and benefit analysis (CBA) showed that additional revenues of $109.49 ha−1 yr−1 for maize farms was produced by applying fertilizer N with DCD which is actually equivalent to 6.02% increase in grain revenues. In comparisons, DMPP application produced less monetary benefit of $15.67 ha−1 yr−1. Our findings showed that DCD had an advantage of bringing more net monetary benefit over DMPP. But this may be weakened by the higher toxicity of DCD than DMPP especially after continuous DCD application. Alternatively, an option related to net monetary benefit may be achieved through applying DMPP in alkaline soil and reducing the cost of purchasing DMPP products.eir performances across field sites is less clear.
A study in New Zealand showed that nitrogen inhibitor applied to grazed pastures reduced nitrate leaching from urine patches by 59% and nitrous oxide emissions by 82%, as well as increasing herbage production by 30%. Its mandatory that sufficient nitrogen can be preserved to provide additional growth to plants because there are many factors that control both the rate of nitrification and the activity of the inhibitor, there is considerable variability in the reduction in the amount of nitrate leached, the reduction in nitrous oxide produced, economic return and the potential benefits associated with their use.
