Research ArticleNitrogen (N) is a major fertilizing element for plants.
The distribution of N in legumes is influencing the efficiency of
the next crop. Nitrogen storage in legumes is actually estimated
by N fixation in shoots, whereas there is little knowledge on the
contribution of roots and nodules to legume N and soil N. Here,
we studied the contribution of roots and nodules of grain and
pasture legumes to plant N and soil N in Mediterranean fields.
Experiments were run under rainfed conditions for a 2-year
period in three regions of Portugal. Entire plants including top
plant and visible roots and nodules were sampled at the end of
the growing seasons for grain legumes, sweet and yellow lupine,
and over two harvests in case of pastures. N2 fixation was measured
for grain legumes and pasture legumes using 15N tracing.
Our results show that aboveground N concentration did not vary
among legumes, but differed in the belowground tissues. Field
studies show that 7–11%of total legume N was associated with
roots and nodules. Data also show an allocation of 11– 14 kg N fixed t−1 belowground dry matter in indeterminate
legumes, which represents half the amount of total aboveground
plant. This finding demonstrates that investigation relying only
on shoot Nunderestimates the role of legumes for soil N fertilityinfo:eu-repo/semantics/publishedVersio