ISSN:
1432-0789
Keywords:
N2 fixation
;
Natural 15N abundance
;
N-difference method
;
Atmosphere-derived N
;
Non-nodulating genotype
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary 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 Bradyrhizobium strain increased the percentage of atmospherederived 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00335857
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