THE PRESENT investigation was carried out in the summer/ ……autumn season of 2010-2011/ 2011-2012 in citrus grove of the Scholl Farm of Universidade Estadual de Londrina – Paraná -Brasil. Eighteen 15-year-old Montenegrina mandarin (Citrus reticulata) trees grafted on Rangpur lime rootstock planted at 7 x 4m apart were selected to study the impact of some cover crop species on various soil and citrus trees properties. Six treatments; cultivating Stylosanthes guianensis var. vulgaris, Clitoria ternatea, Crotalaria juncea, Eleusine coracana, Mix of (Stylosanthes guianensis var. vulgaris, Clitoria ternatea and Eleusine coracana) and the fallow as control. Soil moisture and temperature; mandarin tree canopy and yield, cover crop density, biomass and root system; weed identification and density were measured. Both Clitoria ternatea and the Mix of (Stylosanthes guianensis var. vulgaris, Clitoria ternatea, and Eleusine coracana) gave the best results.