Effect of dicyandiamide on the form and recovery of ¹⁵N‐labeled urea in the delayed flood soil system

Abstract

Dicyandiamide (DCD) is a nitrification inhibitor that has been proposed for use in drill-seeded rice. Immobilization of fertilizer NH 4 + -N by soil microorganisms under aerobic conditions has been found to be significantly enhanced in the presence of a nitrification inhibitor. The objective of this laboratory study was to determine if DCD significantly delayed nitrification of urea-derived N, and if this enhanced immobilization of the fertilizer Ν in the delayed-flood soil system inherent to dry-seeded rice culture. Nitrogen-15-labeled urea solution, with and without DCD (1:9 w/w Ν basis), was applied to a Crowley silt loam (Typic Albaqualf) and the soil was incubated for 10 weeks in the laboratory. The soil was maintained under nonflooded conditions for the first four weeks and then a flood was applied and maintained for the remaining 2079 Copyright© 1989 by Marcel Dekker, Inc.

The effect of dicyandiamide addition to cattle slurry on soil gross nitrogen transformations at a grassland site in Northern Ireland

“…Juma & Paul (1983) found that immobilization of fertilizer N by soil microorganisms was significantly enhanced in the present of a nitrification inhibitor. This was attributed to the nitrification inhibitor keeping the applied N in the NH 4 + form for longer and preferential utilization of NH 4 + by heterotrophic microorganisms (Norman & Wells 1989). Although in the current study I NH4_Nlab in the CS treatment was enhanced by DCD in June 2010, the opposite occurred in March 2011.…”