Assessing nitrogen fixation of faba bean for the prairies

Pulses benefit crop rotations by diversifying cropping options, reducing problems associated with monoculture, and they add some nitrogen to the succeeding crop.  Nitrogen in the past two years has become an increasingly expensive crop input, so reducing reliance on fertilizer by increasing the nitrogen fixation contribution is a sustainable solution.  Legumes like pea, bean, chickpea, lentil and faba can make their own nitrogen by nitrogen fixation, a process which occurs in special nodules formed on the roots by a symbiotic relationship with rhizobia bacteria and the host plant. Recently low tannin faba have been bred at the Crop Development Center, University of Saskatchewan, making faba an attractive crop for food and feed. Faba is a larger crop in terms of height, stem thickness and biomass than pea, and it is a cool season crop that is also fairly tolerant of temperature and drought stress.  Faba is superior to pea in stressful years with drought and heat.  The standing biomass of stubble and nitrogen fixation ability of faba makes it by far the best candidate to contribute greater amounts of nitrogen to succeeding crops in the rotation than the current contributions from pea and lentil.  The first objective is to improve the nitrogen contribution of pulses to the rotation by assessing the nitrogen budget of faba bean, a crop likely to have greater nitrogen fixation and growth than pea and lentil.  The second is to measure the biomass and nitrogen content of a range of faba genotypes and cultivars.  The third objective is to assess the nitrogen fixation ability of faba genotypes by shoot N metabolism under typical dryland prairie conditions and controlled stress conditions, and develop a specific amino-acid screening method to screen for high N fixation.  We intend to use the results to screen a wider range of germplasm for improving future varieties.