Title: CONTRIBUTION OF N<sub>2</sub> FIXATION TO FIELD BEAN AND PEA N UPTAKE OVER THE GROWING SEASON UNDER FIELD CONDITIONS IN SOUTHERN ALBERTA
Abstract: Dinitrogen fixation with field bean (Phaseolus vulgaris L. 'GN1140') and pea (Pisum sativum L. 'Trapper') over the growing season under field conditions was determined using 15 N isotope dilution methods. Levels of N 2 fixation were low during the early part of the growing season for both bean and pea, and increased later in the growing season. At physiological maturity, GN1140 fixed over 91 kg N ha −1 , contributing between 60 and 90% of the N in the bean plants. Pea fixed 117 kg N ha −1 , which constituted a maximum of 57% of the pea plant N. More N was contained in the bean and pea pods than was fixed over the growing season. Key words: Bean (field), pea, Phaseolus vulgaris, Pisum sativum, 15 N dilution