Inhibition of Nitrification in Soil by Allelochemicals Derived from Plants and Plant Residues

Abstract

Literature on allelopathy reflects wide interest in hypotheses that plants and plant residues release allelochemicals that inhibit nitrification in soil. This chapter aims to review evidence for and against current hypotheses concerning inhibition of nitrification by allelo-chemicals. It aims to discuss the general concept of allelopathy and the methodology commonly used to study allelopathic interactions among plants and microorganisms. Most of the research related to allelopathic inhibition of nitrification in soil has been performed with grassland and forest soils, and comparatively little attention has been given to agricultural systems since Russell’s observation that several crop plants appeared to inhibit nitrification. Proof of allelopathic interactions in various ecosystems ultimately requires demonstration that the postulated allelochemicals have an allelopathic effect under the conditions imposed by the ecosystem under study. Rice outlined a theoretical basis for allelopathic inhibition of nitrification by late-succession or climax ecosystems.