Testing the A value method for measuring N2-fixation in kallar grass (leptochloa fusca l.)

A pot experiment was conducted to test the 15N tracer technique (A value approach) and to quantity N2 fixation in kallar grass (leptochloa fusca l.). In order to select an appropriate reference treatment for measuring N2 fixation, and to determine the optimal rate which inhibits N2 fixation, plants received increasing amounts of 15N labeled fertilizer (20, 50, 100, 150 and 200 kg N/ha). Results obtained from this experiment showed the possibility of using the 15N technique (A value approach) for estimating N2 fixation in kallar grass by employing the same plant species that received 150 kg N/ha of N fertilizer as a reference treatment. Such an amount was found to be sufficient in obtaining inhibition of N2 fixation. (Author)