African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6578

Full Length Research Paper

Nitrogen and phosphorus budgets for sorghum and cowpea production under simulated sole- and intercropping systems in low- and medium-P soils

T. P. Tauro1
  • T. P. Tauro1
  • 1Department of Soil Science and Agricultural Engineering, University of Zimbabwe, P.O Box MP167, Mount Pleasant, Harare, Zimbabwe.
  • Google Scholar
J. Adu-Gyamfi
  • J. Adu-Gyamfi
  • Soil Water Management and Soil Crop Nutrition Laboratory, International Atomic Energy Agency (IAEA), Wagramer Strasse 5, P.O Box 100, A-1400 Vienna, Austria.
  • Google Scholar
D. K. C. Dhliwayo2
  • D. K. C. Dhliwayo2
  • Department of Research and Specialist Services, Chemistry and Soil Research Institute, Fifth Street Extension, P. O. Box CY550, Causeway, Harare, Zimbabwe.
  • Google Scholar
L. K. Heng
  • L. K. Heng
  • 3Soil Water Management and Soil Crop Nutrition Laboratory, International Atomic Energy Agency (IAEA), Wagramer Strasse 5, P.O Box 100, A-1400 Vienna, Austria.
  • Google Scholar
Francis O. Wayua
  • Francis O. Wayua
  • 1National Arid Lands Research Centre, Kenya Agricultural Research Institute, P.O. Box 147 (60500), Marsabit, Kenya.
  • Google Scholar
Michael W. Okoth
  • Michael W. Okoth
  • 2Department of Food Science, Nutrition and Technology, University of Nairobi, P. O. Box 29053 (00625), Nairobi, Kenya.
  • Google Scholar
John Wangoh
  • John Wangoh
  • 2Department of Food Science, Nutrition and Technology, University of Nairobi, P. O. Box 29053 (00625), Nairobi, Kenya.
  • Google Scholar


  •  Accepted: 19 December 2012
  •  Published: 31 March 2013

Abstract

 

A greenhouse study was conducted at Seibersdorf, Austria to simulate sorghum-cowpea cropping systems to quantify biological nitrogen fixation (BNF), estimate the nutrient budgets and yield advantages under low-P (Hungary) and medium-P (Waldviertel) soils. The soils were collected from Kompolt in Hungary and Waldviertel in Austria. 15N isotope dilution method was used to quantify BNF while a simple input/output model was used for budgeting. Hungarian soil produced significantly (P< 0.001) higher biomass than Waldviertel soil for both cowpea and sorghum in all cropping systems. However, crops grown in Waldviertel soil accumulated more N than on Hungarian soil. Despite the apparent variations in total N fixed under the sole cowpea and intercrop cropping systems, cowpea derived 14 to 73% of their N from fixation. Intercropping cowpea with sorghum in both soils significantly (P < 0.001) reduced the biomass of cowpea by 30 to 50% and of sorghum by ~70% while increased %N derived from fixation by 20% in Hungarian soil only. Intercropping had > 1.0 land equivalency ratio than sole cropping systems. Exporting crop residues in all cropping systems led to nutrients mining while incorporating cowpea residues gave positive N balance. This study demonstrated the potential of intercropping to produce a sustainable cropping system through BNF and sparing of P within the systems.

 

Key words: Sorghum, cowpea, nitrogen and phosphorus budgeting, biological nitrogen fixation, land equivalency ratios.