QUANTITATIVE ABILITIES OF BIOLOGICAL NITROGEN REDUCTION FOR Rhizobium galegae CULTURES BY GOAT'S RUE

The field experiment (microplots) was carried out in 2005-2007 in the experimental site belonging to the University of Podlasie in Siedlce. Nitrogen N-15 at 10.3 at. % enrichment was applied in a form of ((NH4)-N-15)(2)SO4 at the amount of 1.66g per 1 m(2) in early spring. In parallel to goat's rue (Galega orientalis Lam.) cultivation, also plant that did not show the ability of biological N-2 reduction (spring barley (Hordeum sativum) was grown, and it was also fertilized with N-15 in the form of ((NH4)-N-15)(2)SO4 at 10.3 at. % enrichment. The quantitative abilities of biological nitrogen reduction for Rhizobium galegae cultures living together by goat's rue (Galega orientalis Lam.) was determined by means of isotope dilution method. The abundance of at. % N-15 was determined by spectroscopic method on the spectrophotometer NOI-6E, then the amount of nitrogen transferred from the air due to biological N-2 reduction process, was calculated. The yield of as a sum from three cuts of dry matter of tested plant in subsequent study years was [kg . m(- 2)]: 2005 - 1.092; 2006 - 0.831; 2007 - 0.509. The quantity of biologically reduced nitrogen reached up the mean value for three experimental years at the level of 28.863 g N . m(-2) but in each year as follows [g N . m(-2)]: 2005 - 37.603; 2006 - 26.080; 2007 - 22.906 during the whole vegetation period.