Dicyandiamide (DCD) is one of the longest-established nitrification inhibitors in agriculture, used for over four decades to slow the conversion of ammonium to nitrate and keep nitrogen available to the crop instead of the drainage system.

The problem: Same mechanism as above: nitrate is mobile, ammonium is not. Left unmanaged, nitrification converts stable soil nitrogen into a form that leaches easily and volatilizes as N₂O — a cost to the grower and a cost to the environment, both avoidable with the right chemistry at the right point in the nitrogen cycle.

How it works: DCD inhibits the ammonia-oxidizing bacteria and archaea that drive nitrification, with minimal disruption to other soil microbial populations. It’s typically coated onto urea or blended directly into granular nitrogen fertilizers, so the inhibitor is distributed evenly alongside the nitrogen source itself. Because DCD is broken down gradually in soil, its inhibitory effect fades over a period of weeks rather than shutting off abruptly — giving a controlled, tapering protection window rather than a hard cutoff.