Fate and efficiency of 15N-labelled slow- and controlled-release fertilizers

Abstract

Slow- and controlled-release N fertilizers are designed to increase efficiency and reduce N losses by better synchronizing N availability with plant demand. This paper reviews the use of 15N with these fertilizers to collect quantitative data on the efficiency, residual value and N losses for which relatively few data are available compared with conventional labelled urea and ammonium-based fertilizers. In general, studies of slow-release forms (isobutylidene diurea, oxamide, ureaform) with rice and upland crops show one or more benefits, including improved N uptake efficiency, and reduced N losses via leaching or NH3 volatilization under conditions which favor such losses (coarse textured s..