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Phosphorus deficiency is widespread in the subhumid highlands of eastern Africa but there are few data on the effect of P deficiency on the growth of agroforestry tree species. We studied the effect of P application on growth, nutrient uptake and dry matter partitioning in young trees of Calliandra calothyrsus, Cedrela serrulata, Eucalyptus grandis, Grevillea robusta, Markhamia lutea, Senna spectabilis, and Sesbania sesban on a P-deficient soil (Kandiudalfic Eutrudox, bicarbonate-EDTA extractable P=1mgkg-1) in western Kenya. The treeswere grown at two P levels (control and 500kg added Pha-1) at 1m2 spacing in a randomized complete block design with three replications. Leaf K concentrations were in the low range forall species (5-9mgg-1) and K deficiency may have limited responses to P. Averaged over species, P addition increased aboveground shoot dry matter by a factor of 2.6 at 62 and 124 days, but the response decreased to 1.3 at 325 days. The increases at 62 days were large in sesbania (5.4) and eucalyptus (3.2) but small in calliandra (1.4) and markhamia (1.1). Relative response to P was more strongly correlated with shoot growth rate per unit root length among species than with shoot growth rate alone. Calliandra, which had high early growth rate but low response to added P, had an exceptionally high root length (6.0kmm-2) compared with the other species (0.3-2.1kmm-2). P addition increased N and P content but decreased final shoot K content in sesbania and calliandra, and had little effect on K content in the other species. The high-yielding species (eucalyptus, sesbania and calliandra) accumulated more than 30g N and 2g Pm-2 in shoots in 325 days of growth. The proportion of total shoot N in wood (branch + stem) was in a higher range (67-75%) in the shrubby species (sesbania, calliandra, senna) than in the upperstorey tree species (38-43%). Slow early shoot growth relative to totalro [ABSTRACT FROM AUTHOR]