Contrasts of nitrapyrin, dicyandiamide, and iso-butylidene diurea effects on total inorganic soil nitrogen

Abstract While much research has been done with nitrification inhibitors, little information exists on their effects on total inorganic soil nitrogen (N) (TISN) (NH4 +‐N + NO3 ‐‐N). The objective of this study was to compare the effects of 2‐chloro‐6‐(trichloromethyl)‐pyridine (nitrapyrin) and dicyandiamide (DCD) on TISN concentrations and to compare the effects of the nitrification inhibitors with those of IBDU, a slow release N source. Effects of the three N‐amendments were compared in soil planted to potato (Solanum tuberosum L. cv. Atlantic). Treatments were combinations of N at 67, 134, and 202 kg/ha; and five N‐amendments, nitrapyrin at 0.56 and 1.12 kg/ha, DCD at 5.6 and 11.2 kg/ha, and isobutylidene diurea (IBDU) applied as one‐third of fertilizer N. Studies were conducted on an Arenic ochraqualf, a Grossarenic Paleudult, and a Grossarenic Paleaquult. Concentrations of TISN were influenced by nitrapyrin rate in five of sixteen year‐ location‐sampling date combinations. Of the five, all involved in...