Lotus tenuis biological nitrogen fixation and performance contribute to defining its strategic role in the Salado River Basin lowlands (Argentina)

Abstract

Background and Aims : Forage production is a major challenge in the Salado River Basin, Argentina’s largest livestock raising area. The successful naturalization of the European legume Lotus tenuis has been of productive and environmental relevance to the region. The aim of this study was to evaluate the strategic contribution of L. tenuis, reporting for the first time the B value for this species in these marginal environments for agriculture. Methods The 15N natural abundance method was used to evaluate the BNF of L. tenuis in soil plots. Non-leguminous weed species in the same plots were utilized as reference plants. Simultaneously, evaluations were carried out in the greenhouse to determine the B value of L. tenuis and the relative reproducibility of the field experiments. Results The results showed that L. tenuis promotion was accompanied by an increase in forage quality, due to the predominance of this C3 legume species over C4 species. Moreover, its contribution to N inputs to the system through BNF with native rhizobia was about 80%, a highly relevant percentage for these constrained agroecosystems where the presence of legumes is very scarce. Conclusions This study supports the hypothesis that L. tenuis promotion plays a strategic role in ecosystem sustainability, especially in soil constrained areas. Together with previously published data, including information on ruminant management, the results contribute to supporting the idea that the naturalized legume plays a strategic role in the sustainability of marginal agricultural soils.