this work aimed to evaluate the effect of phosphorus fertilization on nodulation, litter deposition and root system development of m. caesalpiniifolia benth, before and after pruning, at the itambé experimental station of pernambuco agronomical institute - ipa in pernambuco, brazil. treatments were levels of phosphorus fertilization (0, 100 and 200 kg.ha-1 of p2o5) arranged in a randomized block design with six replicates in block i and seven in block ii, with the criterion for block formation being uniformization cut date. samplings were taken before and after pruning of the aerial part root length and root, nodule and litter dry matter had similar results before and after pruning. nodule numbers before pruning were 2, 15 and 6 for 0, 100 and 200 kg.ha-1 of p2o5, respectively, and 1, 6 and 7 after pruning. average root lengths ranged from 552 to 734 cm before and from 389 to 455 cm after pruning. the number of nodules presented variation only from august to november 2005, with values from 2 to 15 and from 1 to 7 nodules, before and after pruning, respectively.