Biodiversity is a key to achieve sustainable agriculture. The use of forage crop can promote biodiversity in small holder farming. This study analyzed the establishment of three forage crops (berseem clover (Trifolium alexandrinum L.), ryegrass (Lolium multiflorum Lam.) and oat (Avena sativa L.) with the aim to introduce them into the farmer’s crop system. Their competitive ability against weeds was also evaluated. Establishment rate was 33, 40.8 and 97% for berseem, ryegrass and oat, respectively. The low establishment for berseem and ryegrass may be attributed to inadequate sowing period characterized by high temperature and low soil humidity. This is in addition to the allelopathic effect of previous crop for berseem. There was a statistically significant interaction between forage crops and sampling dates on weed density (p < 0.000). Berseem was able to suppress weed more than other crops with the lowest weed densities in three sampling dates (56.7, 37.3 and 23.7 plants/m2). Berseem clover was more competitive due to its leaf area and plant architecture as a leguminous plant. Furthermore, its ability to fix atmospheric nitrogen permits to suffer less than ryegrass and oat in deficiency of  fertilizer. At third sampling date, ryegrass was able to restrain weed density with an intermediate developed canopy. It did not differ significantly from weed density in berseem. Oat crop was the most weed invaded along the season. Weeds represented 43.2% and 47.8% in second and third sampling date, respectively. Poor soil, fertilizer absence and lack of moisture influenced negatively oat growth causing this invasion. A negative Pearson correlation (p<0.001) between crop biomass and weed density was assessed in berseem and oat indicating that weed competition was translated into a decrease of these crop biomass. Crop management created a more favorable environment for the success of these forage crops in the small holders crop system.