African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6858

Full Length Research Paper

Utilization of phosphorus from different sources by genotypes of promiscuous soybean and cowpea in a low-phosphorus savanna soil

  O. C.  Nwoke1*, J. Diels1,3, R. C. Abaidoo1 and N. Sanginga2        
  1Soil Research Unit, International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, c/o Lambourn, Carolyn House, 26 Dingwall Road, Croydon CR9 3EE, UK. 2TSBF-CIAT, ICRAF Campus, United Nations Avenue, P. O. Box 30597, Nairobi, Kenya.3Division of Soil and Water Management, Department of Land Management and Economics, K.U. Leuven, Kasteelpark Arenberg 20, 3001, Heverlee, Belgium.
Email: [email protected]

  •  Accepted: 22 April 2007
  •  Published: 30 April 2007



The differential ability of genotypes of soybean (Glycine max) and cowpea (Vigna unguiculata) to thrive under low-phosphorus (P) conditions by utilising P from sources with low solubility was assessed in a greenhouse study with a low-P savanna soil collected from a research field in Fashola, south-western Nigeria. The P sources added (21 mg P kg-1 soil) were calcium phosphate (Ca-P), iron phosphate (Fe-P), aluminium phosphate (Al-P), and triple superphosphate (TSP). Soil without P addition served as a control. The soybean genotypes were TGm 1039, TGm 1196, TGm 1293, TGm 1360, TGm 1420, TGm 1511, and TGm 1540. The cowpea genotypes were Dan‑ila, IT89KD-349, IT89KD-391, IT90K-59, and IT82D-716. Nearly all the soybean genotypes significantly increased their shoot dry matter yield (DMY) and accumulation of P from the various sources when compared with the control; the ranking for P acquisition was control<Al-P<Fe-P<Ca-P=TSP. The shoot DMY and shoot P accumulation of most of the cowpea genotypes were also significantly increased by the addition of Ca‑P, Fe-P, and TSP; the addition of Al-P had no significant effect. The cowpea genotypes varied widely in acquiring P from the P sources. However, the general ranking was control=Al‑P<Fe‑P<Ca‑P=TSP. For both crop species, the shoot DM yields under Ca-P and TSP treatments were not significantly different. From the analysis of shoot P accumulation with the Additive Main Effects and Multiplicative Interaction (AMMI) model, the cowpea genotype IT89KD-391 was better than other genotypes with Ca-P as P source; genotype IT90K-59 was better when Fe-P was the P source. In contrast, most of the soybean genotypes appeared to have access to the P sources in a similar manner


Keywords: Soybean, cowpea, genotypes, savanna soil, sparingly soluble phosphorus.