@article{icrisat4451,
           title = {Nitrogen accumulation in three legumes and two cereals
with emphasis on estimation of N2 fixation in the legumes
by the natural15 N-abundance technique},
       publisher = {Springer Verlag},
          author = {T Yoneyama and P T C Nambiar and K K Lee and B Srinivasa Rao and J H Williams},
           pages = {25--30},
            year = {1990},
          volume = {9},
         journal = {Biology and Fertility of Soils},
          number = {1},
             url = {http://oar.icrisat.org/4451/},
        abstract = {N accumulation and natural "N ahundance
in three legumes (groundnuts, cowpeas, and
soybeans) and in two cereals (sorghum and maize)
were investigated over two seasons in Alfisols with and
without N fertilization. Using the N uptake and natural
"N abundance of non-nodulating plants as the indication
of N derived from soil and fertilizer, the per
cent N derived from atmospheric N2 was calculated
for nodulated plants. In the first experiment, the
groundnut genotype contained 85\% atmospherc-derived
N, but the percentage decreased with N application,
Estimates of atmosphere-derived N by the N-difference
and 15{\texttt{\char126}}-abundanctee chniques gave identical
results. The percentages of atmosphere-derived N estimated
by the two methods at different stages of
groundnut growth were also similar. In the second experiment,
atmosphere-derived N was estimated in
plants grown with 0-200 kg ha-' applied N. The estimated
atmosphere-derived N ranged from 42\% to
61 \% for groundnuts from 33\% to 77\% for cowpeas,
and from 24\% to 48\% for soybeans, depending on the
amount of N applied. Inoculation with a Bradyrhizobium
strain increased the percentage of atmospherederived
N in soybean plants grown without any fertilizer
N. The natural "N abundance of sorghum and
maize was very close to that of the non-nodulating
groundnut, suggesting that these cereals can be used as
reference plants in the estimation of atmosphere-derived
N by the natural "N-abundance method.}
}