%0 Journal Article
%@ 0178-2762
%A Yoneyama, T
%A Nambiar, P T C
%A Lee, K K
%A Srinivasa Rao, B
%A Williams, J H
%D 1990
%F icrisat:9704
%I Springer-Verlag
%J Biology and Fertility of Soils
%K N2 fixation, Natural 15N abundance, N-difference method, Atmosphere-derived N, Non-nodulating genotype, Cereals, Legumes
%N 01
%P 25-30
%T Nitrogen accumulation in three legumes and two cereals with emphasis on estimation of N2 fixation in the legumes by the natural 15N-abundance technique
%U http://oar.icrisat.org/9704/
%V 09
%X 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.
%Z ICRISAT Journal Article No. 876