Nitrogen (N) is a major element that plant need for growth. Legumes are nitrogen-rich plants that are named ‘green fertilisers’ because legume residues enrich the soil in nitrogen after plant death. This fertilising effect is actually assessed by measuring shoot N concentrations, which does not take into account root contribution. Agronomists Carranca et al. indeed found that roots contain 7 – 11% of total legume N. The power of legumes as fertilisers for the next crop is thus underestimated.
