The phosphorus requirements of five consecutive potato crops on an Andept in Rwanda
- 28 Downloads
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 WordsSolanum tuberosum residual P solution P temperature
Unable to display preview. Download preview PDF.
- 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.Google Scholar
- 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.Google Scholar
- 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.Google Scholar