Estimates of N2 Fixation in Ecosystems: The Need for and Basis of the 15N Natural Abundance Method

摘要: Absolute instantaneous rates of biological N2 fixation can be measured accurately under carefully controlled laboratory conditions. Seeking an integrated value the quantity fixed over, for example, a growing season adds enormously to problem. These difficulties are considerably magnified in natural field settings, compared agricultural settings. Several articles have reviewed available methods use (Burris 1974; Hardy and Holsten 1977; Bergersen 1980; Turner Gibson Knowles 1980, 1981; Rennie 1983; Silvester 1983) with authors expressing various degrees satisfaction methods.