African Journal of
Plant Science

  • Abbreviation: Afr. J. Plant Sci.
  • Language: English
  • ISSN: 1996-0824
  • DOI: 10.5897/AJPS
  • Start Year: 2007
  • Published Articles: 757

Full Length Research Paper

Upland rice response to nutrient application in Uganda

K. C. Kaizzi
  • K. C. Kaizzi
  • National Agricultural Research Laboratories (NARL), Kawanda, P. O. Box 7065 Kampala, Uganda.
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J. Byalebeka
  • J. Byalebeka
  • National Agricultural Research Laboratories (NARL), Kawanda, P. O. Box 7065 Kampala, Uganda.
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O. Semalulu
  • O. Semalulu
  • National Agricultural Research Laboratories (NARL), Kawanda, P. O. Box 7065 Kampala, Uganda.
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I. Alou
  • I. Alou
  • National Agricultural Research Laboratories (NARL), Kawanda, P. O. Box 7065 Kampala, Uganda.
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W. Zimwanguyizza
  • W. Zimwanguyizza
  • National Agricultural Research Laboratories (NARL), Kawanda, P. O. Box 7065 Kampala, Uganda.
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A. Nansamba
  • A. Nansamba
  • National Agricultural Research Laboratories (NARL), Kawanda, P. O. Box 7065 Kampala, Uganda.
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E. Odama
  • E. Odama
  • National Agricultural Research Laboratories (NARL), Kawanda, P. O. Box 7065 Kampala, Uganda.
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C. S. Wortmann
  • C. S. Wortmann
  • Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE USA.
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  •  Received: 03 March 2014
  •  Accepted: 04 September 2014
  •  Published: 30 September 2014

Abstract

Upland rice (Oryza spp.) yields are low in Uganda, partly because of little fertilizer use. Three on-station trials and two clusters of on-farm trials were conducted in Uganda at approximately 1000 m elevation to determine: yield response to N, P and K application; economically optimal nutrient rates (EOR); and N use efficiency components. Mean grain yield, with hulls, was 1.3 and 3.7 Mg ha-1 with 0 and 100 kg ha-1 N applied, respectively. Grain yield response to applied P when compared with N was less, and mean yield was not increased with K application. Depending on fertilizer cost relative to grain price (CP), mean EOR ranged from 54 to 92 kg ha-1 N and 17 to 30 kg ha-1 P. Equations were determined for yield response, estimation of EOR, and the benefit: cost ratio (BC) for fertilizer N and P use. Grain N concentration and N harvest index at EOR were 1.55 and 0.55 kg kg-1, respectively. Mean recovery efficiency, partial factor productivity and agronomic efficiency declined with increasing N rate and were 0.75, 41 and 28 kg kg-1, respectively, at the EOR. Fertilizer N and P use can be highly and moderately profitable, respectively, for upland rice production in Uganda with high N recovery and agronomic efficiency. In maximizing net return on finance-constrained investment in fertilizer use, CP and investment capacity needs to be considered.

 

Key words: Economic, fertilizer use, nitrogen, phosphorus, potassium, use efficiency.