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Electro-ultra filtration (EUF) is seldom used for plant nutrient studies. Reproducibility of its anode extract volumes and phosphorus (P) contents was assessed in tropical Alfisols and Ultisols of Nigeria. Using quadratic regression model, relative yields (R.Y %) of potato (Solanum tuberosum) and cassava (Manihot esculenta Cranz) on the soils were related to P extracted by Bray-1 or EUF (at 10, 30 and 35 minutes desorption time). Uncertainties (coefficients of variation, CV %) in EUF extract volumes and P contents were low (0 -14.6% and 0.02 -18.1%, with means of 5.9% and 8.35%, respectively). R.Y % of the test crops correlated significantly (p 5 0.05) with EUF-P while only potato R.Y% correlated well with Bray-1. Evidently, the EUF technique could be used for fertilizer P recommendation as EUF-P 30 5 0.36, 0.36 -0.60 and 4 0.60 mg P kg 71 were found to indicate low, medium and high P status, respectively.