American Potato Journal

, Volume 63, Issue 3, pp 121–129 | Cite as

The phosphorus requirements of five consecutive potato crops on an Andept in Rwanda

  • P. Vander Zaag
  • C. Kagenzi


Farmers in Rwanda do not apply P fertilizer on their crops. Bray and Kurtz #1 extractable P levels are generally less than 2 ppm on these soils. Therefore, a long-term experiment was established to determine the yield response of potatoes to P fertilizer. A maximum accumulated yield of 130 t/ha in 5 crops was obtained with 902 kg/ha of P. The no P treatments produced 72% of the average maximum yield. The external P requirements, determined with P sorption isotherms, averaged 0.04 μg/ml if equilibrated at 15 C and 0.02 μg/ml if equilibrated at 25 C for the 5 crops. The residual efficiency of the applied P fertilizer was less than 20%, suggesting that large applications of P are not advisable on Andepts, which have amorphous materials because the applied P is not available for subsequent cropping seasons.

Additional Key Words

Solanum tuberosum residual P solution P temperature 


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Copyright information

© Springer 1986

Authors and Affiliations

  • P. Vander Zaag
    • 1
  • C. Kagenzi
    • 2
  1. 1.International Potato CenterManilaPhilippines
  2. 2.Institut des Science Agronomique du RwandaRuhengeriRwanda

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