Potential Denitrification: Concept and Conditions of its Measurement

Denitrification plays important roles in nitrogen cycling and management affecting both the environment and agricultural systems. Potential denitrification has a role in comparison of denitrification magnitudes in different soils. This paper discusses the concept of potential denitrification in relation to denitrification rate and conditions under which it is determined. The terminologies such as denitrification activity, intensity, capacity and potential are variously applied to describe denitrification rates, but the use of these terms is not consistent. Similarly, the concept of potential denitrification is variously espoused. Many researchers measure potential denitrification under entirely different conditions and express the values in divergent units making meaningful comparisons between soils unfeasible. It is proposed that the concept of potential denitrification embraces the principle of maximum attainable denitrification rate under optimal conditions within the limitations of natural setting. The steepest slope, Y/X, on the cumulative nitrous oxide production - time curve defines the potential denitrification value. The conditions under which potential denitrification is to be measured and the units in which its values are to be expressed are discussed. Keywords: denitrification activity, denitrification capacity, denitrification intensity, denitrification rate, potential denitrification Resume La denitrification joue un role important dans le cycle et la gestion de l'azote et affecte l'environnement et les systemes agricoles. La denitrification potentielle intervient egalement lors de la comparaison des degres de denitrification dans differents sols. Cet article revoit le concept de la denitrification potentielle par rapport au taux de denitrification et les conditions sous lesquels on la determine. Les terminologies telles qu'activite, intensite, capacite et potentiel de denitrification sont differemment appliquees pour decrire les taux de denitrification, mais l'utilisation de ces termes manque de consistance d'ou le concept de la denitrification potentielle est compris differemment. Beaucoup de chercheurs mesurent la denitrification potentielle dans des conditions entierement differentes et en expriment les valeurs en unites diverses, ce qui rend impossible des comparaisons utiles entre les sols. On propose que le concept de denitrification potentielle couvre le principe du taux possible de denitrification maximale dans des conditions optimales et dans les limites des conditions naturelles. La pente la plus raide, , Y/X, sur la production cumulative du protoxyde d'azote, sur la courbe obtenue au cours d'une periode, definit la valeur potentielle de denitrification. Les conditions sous lesquelles la denitrification potentielle doit etre mesuree, et les unites dans lesquelles ses valeurs doivent etre exprimees sont passees en revue. Mots cles: activite de denitrification, capacite de denitrification, intensite de denitrification, taux de denitrification, denitrification potentielle (Discovery and innovation: 14(1-2): 84-91)