The fixation of atmospheric nitrogen in some Fabaceae species

In two replications performed on different dates the fixation of atmospheri c nitrogen was measured in some species of the family Fabaceae. The first r eplication involved 48 species and the second 49 species. On the basis of t he results obtained the species were divided into four groups. Besides Lath yrus sativus the best nitrogen fixers were Trifolium incarnatum, Lotus corn iculatus, Trifolium hybridum, Trifolium pratense, Trifolium repens, Trifoli um ambiguum and annual species of Trifolium resupinatum and Trifolium alexa ndrinum. In the first replication the tested species of the genus Lupinus w ere very good nitrogen fixers. However, in the second replication these spe cies formed no nodules on the roots. To make the comparison of the species tested more effective it is recommended to calculate nitrogenase activity p er 1 g of root dry matter. On the basis of the calculations Lathyrus sativu s, Trifolium pratense 4 n, Trifolium repens and Vicia cracca were good nitr ogen fixers in both replications.