Summary
Two experiments were carried out with two nodulating and non-nodulating soybean isolines, with three different levels of N as (15NH4)2SO4 at the equivalent of 0, 25 and 50 kg N/ha. In the first experiment three seeds were sown in each pot and the plants harvested at 35, 55 and 75 days. In the second experiment only one seed was sown per pot and harvested at 75 days.
Isotope dilution technique and in certain cases natural isotope variation (δ15N) was used to determine directly the origin of nitrogen in the plant, whether from soil, fertilizer or biological N2-fixation. The use of nodulating and non-nodulating isolines enabled comparison with the classical method of estimating N2-fixation by difference from total plant N. Results at the 75 day harvest were similar for either method, but at the earlier harvests, particularly at 35 days, the total-N method was inadequate. The isotope method appeared more sensitive while the total-N method suffered from greater variability with correspondingly high standard errors and significant differences.
It was found that by the 35 and 55 day harvests hardly any N2-fixation had taken place, plant nitrogen being almost entirely derived from soil or fertilizer N. Plants in competition used up soil fertilizer N more rapidly, thus stimulating symbiotic nitrogen fixation. When only one plant was grown in each pot it had a greater proportion of N derived from soil or fertilizer, and less N derived from fixation. In general the15N data showed that only about 25% of the applied fertilizer N was absorbed by the plant.
The nodulating isoline absorbed more N than the non-nodulating plants. This suggests a possible synergistic effect of N2-fixation on N derived from other sources, giving an increase in total-N content of nudulated plants. The N derived from N2-fixation was scarcely detectable in the roots but appeared to be translocated almost entirely to shoots and pods.
With 25 kg N/ha the greater proportion of the nitrogen in the pods was derived from N2-fixation. Even with 50 kg N/ha the nitrogen in the pods derived from fixation remained high, that being derived from fertilizer being less than 15%. About 80% of the nitrogen in the nodules was due to fixation.
In the present experiment the application of 25 kg N/ha appeared sufficient to give maximum N absorption by both isolines. At this level symbiotic fixation by Rhizobium remained high in nodulating plants, while the proportion of total N due to fixation was reduced with 50 kg N/ha.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Allos, H. F. and Bartholomew, W. V. 1955 Effect of available nitrogen on symbiotic fixation. Soil Sci. Soc. Am. Proc.19, 182–184.
Amarger, Noëlle, Mariotti, A. and Mariotti, Françoise 1977 Essai d'estimation du taux d'azote fixé symbiotiquement chez le Lupin par le traçage isotopique naturel (15N). C.R. Acad. Sci. Paris284, 2179–2182.
Beard, B. B. and Hoover, R. M. 1971 Effect of nitrogen on nodulation and yield of irrigated soybeans. Agron. J.63, 815–816.
Bremner, J. M. 1965 Isotope ratio analysis of nitrogen in nitrogen-15 tracer investigations. 1256–1286.In Methods of Soil Analysis. Ed. C. A. Black. Am. Soc. Agron. Madison.
Broeshart, H. 1974 Quantitative measurement of fertilizer uptake by crops. Neth. J. Agric. Sci.22, 245–254.
Carter, J. L. and Hartwig, E. E., 1963 The management of soybeans. In: The Soybean. Ed. A. G. Norman. Academic Press, pp. 194.
Fried, M. and Middelboe, V. 1977 Measurement of amount of nitrogen fixed by a legume crop. Plant and Soil47, 713–715.
Fried, M. and Mellado, L. 1978 A method for determining the amount of nitrogen fixed in the field using15N, 362.In Abstracts and Poster Session, Int. Symp. Limitations and Potential of Biological Nitrogen Fixation in the Tropics, Brasilia, July 18–22, 1977, Plenum Press, New York.
Johnson, J. W., Welch, F. F. and Kurtz, L. T. 1974 Soybeans role in nitrogen balance. III. Res.16, 6.
Proceedings of World Soybean Research Conference 1976 Univ. Illinois, August 1975.
Proksch, G. 1972 Application of mass and emission spectrometry for14N/15N ratio determinations in biological material (Dumas Method).In Isotopes and Radiation in Soil-Plant Relationship Including Forestry. Symposium, IAEA, Vienna, 217–225.
Rep. of the TAC Working Group on the Biology of Yield of Grain Legumes, New Delhi, India, 1974. TAC Secretariat, FAO, Rome (1975).
Ruschel, A. P. and Ruschel, R. 1975 Sinergia da absorção de nitrogênio do solo e da fixação simbiótica de nitrogênio atmosférico dirigida para o aumento do nitrogênio total da soja (Glycine max). Pesq. Agrop. Bras.10, 37–40.
Russell, W. J. and Johnson, D. R. 1975 Carbon-14 assimilate and translocation in nodulated and non-nodulated soybeans. Crop Sci.15, 159–161.
Sears, O. H. and Lynch, O. L. 1951 Importance of inoculation. Soybean Digest11, 15–16.
Vose, P. B., Ruschel, Alaides P. and Salati, E. 1978 Determination of N2-fixation, especially in relation to the employment of nitrogen-15 and of natural isotope variation (Abstracts 89–90, and Proc. II Latin American Bot. Congr.In Press.
Weber, C. R. (1966) Nodulating and non-nodulating soybean isolines. II. Response to applied nitrogen and modified soil conditions. Agron. J.58, 46–49.
Author information
Authors and Affiliations
Additional information
UNDP/IAEA Project BRA 78/006.
Rights and permissions
About this article
Cite this article
Ruschel, A.P., Vose, P.B., Victoria, R.L. et al. Comparison of isotope techniques and non-nodulating isolines to study the effect of ammonium fertilization on dinitrogen fixation in soybean,Glycine max . Plant Soil 53, 513–525 (1979). https://doi.org/10.1007/BF02140722
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02140722