Note on the nitrification-inhibitors in the seeds, bark and leaves of Pongamia glabra Vent.

The manurial value of P. glabra seed-cake in India has been attributed to nitrification inhibitors. In laboratory experiments with soil samples, both seed and bark extracts inhibited the oxidation of NH4-N (NH4-N concn. approx. twice that of controls at 45 days), the effect being slightly greater with the seed extract. Dried leaves had no such effect. It is concluded that components of the alcoholic seed extract may be used to increase the efficiency of ammoniacal fertilizers