Fields with no recent legume cultivation have sufficient nitrogen-fixing rhizobia for crops of faba bean (Vicia faba L.)

Abstract Purpose (1) To assess the biological N fixation (BNF) potential of varieties faba bean ( Vicia L.) cropped with or without compost in an experimental field-scale rotation no recent history legumes, (2) to enumerate soil populations Rhizobium leguminosarum sv. viciae Rlv ), and genetically characterize nodulating strains, (3) compare BNF other sites Britain. Methods was evaluated from 2012 2015 using 15 natural abundance. Treatments were either PK fertilizer compost. Soil rhizobial determined qPCR, symbiotic rhizobia genotyped (16 S rRNA, nodA nodD genes), their capacity assessed ex situ . The reliance legumes on at British estimated a single season, symbionts examined. Results Faba obtained most its through (>80%) regardless variety year. N-accumulation by cvs Babylon Boxer increased treatment 2014/2015. Rhizobial c. 10 5 -10 6 cells g −1 field treatment. 157 microsymbionts grouped into two large nodAD clades; one mainly V. , various legumes. All isolates nodulated, some performed better than commercial inoculant strains. Conclusions can provide nitrogen leave economically valuable residual for subsequent crops. Recent legume cropping northern Europe is not essential effective nodulation: may persist range farmland locations. Nevertheless, there apply elite strains as inoculants soils.