@article{icrisat9704,
           month = {February},
           title = {Nitrogen accumulation in three legumes and two cereals with emphasis on estimation of N2 fixation in the legumes by the natural 15N-abundance technique},
       publisher = {Springer-Verlag},
            year = {1990},
          author = {T Yoneyama and P T C Nambiar and K K Lee and B Srinivasa Rao and J H Williams},
           pages = {25--30},
          volume = {09},
            note = {ICRISAT Journal Article No. 876},
         journal = {Biology and Fertility of Soils},
          number = {01},
        keywords = {N2 fixation, Natural 15N abundance, N-difference method, Atmosphere-derived N, Non-nodulating genotype, Cereals, Legumes},
             url = {http://oar.icrisat.org/9704/},
        abstract = {N accumulation and natural 15N abundance 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 15N 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\% atmosphere-derived N, but the percentage decreased with N application. Estimates of atmosphere-derived N by the N-difference and 15N-abundance techniques 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-1 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 Brady rhizobium strain increased the percentage of atmosphere derived N in soybean plants grown without any fertilizer N. The natural 15N 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 15N-abundance method.}
}