Nitrogen-fixing capacity and productivity of long-term bean herbs in subtaiga zone of Western Siberia

Investigation of biological nitrogen fixation by legumes under various cultivation conditions and increase in coefficient of its use are among the most important problems of agricultural production development. The purposes of this research are to define nitrogen-fixing capacity of long-term bean herbs and the consumption of biological nitrogen by legumes in order to produce forage in subtaiga zone of Western Siberia. The share of nitrogen fixed from atmosphere in order to produce herbs biomass - coefficient of nitrogen fixation (Nf), was determined by comparison with nonleguminous plant - awnless brome. High nitrogen fixation from atmosphere in subtaiga zone was established at wet meadow soil. Birdsfoot deer vetch, blue lupine, meadow and alsike clover produce 66-73% of forage owing to biological nitrogen, while lucerne and galega produce 80-82% (5.58-6.53 t/hectare of dry matter). Herbs nitrogen fixation on gray wood soil 25-31 kg/hectare (16-32%) lower than on meadow alluvial soil, Nf equals 0.53-0.77. Seed inoculation of clover and melilot is better to conduct through legume bacteria strain Kt-1 and K-2, galega lucerne - 912 and 913. Nitrogen fixation by these species of herbs on the gray forest soil reaches 271-389 kg/hectare, the productivity increases by 2.2-3.5 times, Nf equals 0.71-0.78.