In the subhumid zone of Nigeria S. guianensis cv Cook, S. guianensis cv Schofield and S. hamata cv Verano produced low dry matter yields. The role of P in limiting yields was investigated in a field experiment at Kurmin Biri, Kaduna State, Nigeria. Four levels of P2O5, zero. 40, 80 and 120 kg ha-1 were applied to these stylos in 1981 and the experiment was run for two years, without further P additions, in order to determine residual levels. S. guianensis cv Cook responded most to increasing levels of P up to 80 kg P2O5 ha-1; the same trend was shown by cv Schofield but the response was less marked. S. hamata cv Verano did not respond in DM yield but the application of P gave improved seed production and increased P content in the tissue. P levels marginally increased the digestibility of the forage produced. Nodulation was not affected by P application for cv Verano but there was a marked effect in cvs Cook and Schofield. Crude protein was increased by P applications. In the second year, when no additional P was applied, productivity of cvs Cook and Schofield declined by 60-70% but cv Verano remained only slightly affected. P application and legume growth increased organic C and N which suggest possibilities for enhancing integrated crop-livestock systems.