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


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.

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

Literature Cited

  1. 1.

    Banderis, A., D.H. Barter and K. Henderson. 1976. The use of polyacrylamide to replace carbon in the determination of Olsen’s extractable phosphate in Soil. J Soil Sci 27:71–74.

    Article  CAS  Google Scholar 

  2. 2.

    Chien, S.H., N.K. Savant and U. Mokwunye. 1982. Effect of temperature on phosphate sorption and desorption in two arid soils. Soil Sci 133 (3) 160–166.

    Article  CAS  Google Scholar 

  3. 3.

    Fox, R.L. and E.J. Kamprath. 1970. Phosphate sorption isotherms for evaluating the phosphate requirements of soils. Soil Sci Soc Am Proc 34:902–907.

    CAS  Article  Google Scholar 

  4. 4.

    Fox, R.L. and B.T. Kang. 1978. Influence of phosphorus fertilizer placement and fertilization rate on maize nutrition. Soil Sci 125:34–40.

    Article  CAS  Google Scholar 

  5. 5.

    Fox, R.L. and Xue-Yuan Li. 1983. Phosphate fertilizer requirements of weathered soils and residual phosphate fertilizer efficiency as indicated by phosphate sorption curves. Proceedings of a Symposium on Red Soils. Nanjing, China, Nov. 15–19, 1983, in press.

  6. 6.

    Gardner, B.R. and J.P. Jones. 1973. Effects of temperature on phosphate sorption isotherms and phosphate desorption. Commun Soil Sci Plant Anal 4:83–93.

    CAS  Article  Google Scholar 

  7. 7.

    MacKay, D.C., C.R. MacEachern and R.F. Bishop. 1966. Optimum nutrient levels in potato leaves (Solanum tuberosum L.). Soil Sci Soc Am Proc 30:73–76.

    Article  Google Scholar 

  8. 8.

    Mehta, N.C., G.O. Legg, C.A.I. Guring and C. A. Black. 1954. Determination of organic P and soils. I. Extraction method. Soil Sci Soc Am Proc 18:443.

    CAS  Article  Google Scholar 

  9. 9.

    Vander Zaag, P. and R.L. Fox. 1981. Fertility and management of Andepts of Rwanda. Proceedings of the Fourth International Soil Classification Workshop, Kigali, Rwanda, June 2–12, 1981.

  10. 10.

    Vander Zaag, P., R.S. Yost, B.B. Trangmar, K. Hayashi and R.L. Fox. 1984. An assessment of chemical properties for soils of Rwanda with the use of geostatistical techniques. Geoderma 34:293–314.

    Article  CAS  Google Scholar 

  11. 11.

    Vander Zaag, P., R.L. Fox, R. de la Pena, W.M. Laughlin, A. Ryskamp, S. Villagarcia and D.T. Westermann. 1979. The utility of phosphate sorption curves for transferring soil management information. Trop Agric (Trin) 56(2): 153–160.

    CAS  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to P. Vander Zaag.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Vander Zaag, P., Kagenzi, C. The phosphorus requirements of five consecutive potato crops on an Andept in Rwanda. American Potato Journal 63, 121–129 (1986).

Download citation

Additional Key Words

  • Solanum tuberosum
  • residual P
  • solution P
  • temperature