EFFECTIVENESS OF INOCULATION ON BIOLOGICAL NITROGEN-FIXATION AND WATER-CONSUMPTION BY LENTIL UNDER RAIN-FED CONDITIONS

The magnitude of nitrogen fixation and the export of plant N, to the grain and straw, is important to assess the potential of lentil to contribute N to the subsequent cereal in a crop rotation. A field experiment was conducted for 2 consecutive years on a clay soil (very fine, smectitic, thermic, Typic Chromoxerert) at Moshagar, Jordan, in order to assess the effect of inoculation an biological N-fixation and yield of two lentil cultivars, and to determine their water consumption. The study included two lentil cultivars (UJ1, ILL), two rhizobial inoculants (719, 735) and one rate of nitrogen fertilizer. The results showed that UJ1 and ILL cultivars obtained 80 and 83% respectively of their N requirements from the atmosphere. The indigenous strains nodulating lentils were as efficient in N-fixation as the selected inoculant strains. Only in terms of dry matter (grain and straw), was there a significant lentil cultivar effect, UJ1 being more productive than ILL, under all conditions. The UJ1 cultivar exported more N into the grain, straw, and the whole shoot. The nitrogen harvest index was higher with the indigenous rhizobial strains under heat-stressed conditions than with the inoculant strains. Cropping the land with lentil under existing practices would deplete the soil N by 2-11 kg N ha(-1). Water consumption differences between lentil cultivars were insignificant and were not affected by inoculation.