Nitrification inhibitors ‐ Interaction with applied ammonium concentration

Abstract

Soil samples of 50 g clay, clay loam and sandy loam were amended with ammonium sulphate giving 25, 50, 100, 200, and 400 mg nitrogen (N)/kg and with two nitrification inhibitors, Dicyandiamide (DCD) and N‐Serve (N‐S) each at two levels calculated relative to the N applied, 1 and 5%, and 0.5 and 1%, respectively. Water was added to moisture field capacity and the samples were incubated at 30°C for 7, 14, 28, and 56 days, each treatment and timing in three replicates. The lower level of application of nitrification inhibitors was not effective. Nitrate‐N (NO₃‐N) recovery peaked at 28 days and did not change appreciably later, except the 1% N‐S treatments where a flush of NO₃ appeared at the 56th sampling day. The nitrification inhibitory effects of the two inhibitors were enhanced at the 200 and 400 mg/kg ammonium‐N (NH₄‐N) application in all three soils. Nitrification inhibition was not related to salt concentrations as measured by electrical conductivity.

Notes

Graduate student. The paper is based on a thesis for partial fulfillment of requirements for a M.Sc. degree.

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