Skip to main content

Mineral N effects on cowpea and soybean crops in a Nigerian soil

I. Development, nodulation, acetylene reduction and grain yield


In a Nigerian soil depleted in available N, fertilizer-N enriched in15N was applied at 25 and 100 kg N/ha to crops of four cowpea and two soybean cultivars. Soil-N availability was estimated with three non-fixing crops, non-nodulating soybean, maize and celosia. With sequential harvests we examined the development of the fixing crops, as well as their nodulation profiles and acetylene reduction activities, and the patterns obtained were correlated with uptake of mineral-N. At low levels of mineral-N, excellent nodulation (up to 580 mg dry weight/plant) and very high acetylene reduction activities (up to 208 μmoles/plant/h) were recorded. Although fertilizer-N utilizations were low, 12% and 28% at 25 and 100 kg N/ha respectively, the lower application had a transient adverse effect on nodule development and the higher application had a long-term adverse effect on nodule formation, nodule development and acetylene reduction activity. Cowpea nodule mass reached maximum levels at early pod-fill except at 100 kg N/ha at which it continued to increase into late podfill. In contrast, soybean nodulation did not peak at any level of N but increased into late pod-fill.

This is a preview of subscription content, access via your institution.


  1. 1

    Allos H F and Bartholomew W V 1959 Replacement of symbiotic fixation by available nitrogen. Soil Sci. 87, 61–66.

    CAS  Google Scholar 

  2. 2

    Ayanaba A and Lawson T L 1977 Diurnal changes in acetylene reduction in field-grown cowpeas and soybeans. Soil Biol. Biochem 9, 125–129.

    Article  CAS  Google Scholar 

  3. 3

    Ayanaba A and Nangju D 1973 Nodulation and nitrogen fixation in six grain legumes.In Proceedings of the First IITA Grain Legume Improvement Workshop. pp 198–204. International Institute of Tropical Agriculture. Ibadan, Nigeria.

    Google Scholar 

  4. 4

    Chowdhury M S 1977 Response of soybean to Rhizobium inoculation at Morogoro, Tanzania.In Biological Nitrogen Fixation in Farming Systems of the Tropics. pp 245–253, Eds. A. Ayanaba and P J Dart, John Wiley and Sons, Ltd., Chichester.

    Google Scholar 

  5. 5

    Deibert E J, Bijeriego M and Olson R A 1979 Utilization of15N fertilizer by nodulating and non-nodulating soybeans isolines. Agron. J 71, 717–723.

    CAS  Google Scholar 

  6. 6

    Eaglesham A R J, Minchin F R, Summerfield R J, Dart P J, Huxley P A and Day J M 1977 Nitrogen nutrition of cowpea (Vigna unguiculata) III. Distribution of nitrogen within effectively nodulated plants. Expl. Agric. 13, 369–380.

    CAS  Google Scholar 

  7. 7

    Eskew D L, Eaglesham A R J and App A A 1981 Heterotrophic15N2 fixation and distribution of newly fixed N in a rice-flooded soil system. Plant Physiol. 68, 48–52.

    CAS  Google Scholar 

  8. 8

    International Institute of Tropical Agriculture 1976 Farming systems.In Annual Report for 1975. pp. 9–74. Ibadan, Nigeria.

  9. 9

    International Institute of Tropical Agriculture 1979 Farming systems program.In Annual Report for 1978, pp 65–106. Ibadan, Nigeria.

  10. 10

    International Institute of Tropical Agriculture 1979 Grain legume improvement program.In Annual Report for 1978. pp 27–46. Ibadan, Nigeria.

  11. 11

    Johnson J W, Welch L F and Kurtz L T 1974 Soybeans’ role in nitrogen balance. Illinois Res. 16, 6–7.

    Google Scholar 

  12. 12

    Nangju D 1980 Soybean response to indigenous rhizobia as influenced by cultivar origin. Agron. J. 72, 403–406.

    Google Scholar 

  13. 13

    Sinclair T R and de Wit C T 1976 Analysis of the carbon and nitrogen limitations to soybean yield. Agron. J. 68, 319–324.

    CAS  Google Scholar 

  14. 14

    Summerfield R J, Huxley P A and Steele W 1974 Cowpea(Vigna unguiculata (L.) Walp.. Field Crop Abstr. 27, 301–312.

    Google Scholar 

  15. 15

    Summerfield R J, Dart P J, Huxley P A, Eaglesham A R J, Minchin F R and Day J M 1977 Nitrogen nutrition of cowpea (Vigna unguiculata). I. Effect of applied nitrogen and symbiotic nitrogen fixation on growth and seed yield. Expl. Agric. 13, 129–142.

    CAS  Google Scholar 

Download references

Author information



Rights and permissions

Reprints and Permissions

About this article

Cite this article

Eaglesham, A.R.J., Ayanaba, A., Ranga Rao, V. et al. Mineral N effects on cowpea and soybean crops in a Nigerian soil. Plant Soil 68, 171–181 (1982).

Download citation

Key words

  • Acetylene reduction
  • Cowpea
  • Fertilizer-N
  • Glycine max
  • Nitrogen-15
  • Nodule
  • Soybean
  • Vigna unguiculata
  • Yield