Tropical Grasslands (2006) Volume 40, 150156
Chemical composition, dry matter production and yield dynamics of tropical grasses mixed with perennial forage legumes
Z. TESSEMA1 AND R.M.T. BAARS2
1 Department of Animal Sciences, Alemaya
University, Dire Dawa, Ethiopia
To evaluate the dry matter (DM) yield, relative yield, relative total yield, aggressivity index and relative crowding coefficient, stability and chemical composition of grass-legume mixtures, an experiment was conducted in a randomised complete block design with 3 replications. Chloris gayana, Panicum coloratum, Phalaris aquatica, Desmodium uncinatum and Medicago sativa were planted as both pure stands and grasslegume mixtures in the first week of June 1996 to give 11 treatments, and observations continued for 3 years. The highest DM yields were obtained from pure Chloris and Panicum plus 4 mixtures: Chloris-Medicago, Chloris-Desmodium, Panicum-Medicago and Panicum-Desmodium mixtures, with 13–15 t/ha per year in Years 2 and 3. Phalaris and its mixtures yielded well in the first year, but declined steadily after that. The relative total yields of mixtures were greater than ‘unity’, indicating that the DM yields of mixtures were higher than those of an average of the pure stands. The mean relative crowding coefficient values of Panicum and Chloris in mixtures with Medicago and Desmodium were high, indicating that they produced high DM yields in the grass-legume combinations. Both Chloris and Panicum showed positive aggressivity index values in the grasslegume mixtures, indicating that both were more competitive than the legumes, with Panicum more competitive than Chloris. Pure legume stands and grass-legume mixtures produced forage with higher CP and lower fibre concentrations than pure stands of grass. Mixtures of Chloris and Panicum with Desmodium and Medicago seem quite productive and these grass-legume mixtures should be evaluated under smallholder farm conditions. Issues to be addressed are animal performance under both cut-and-carry systems and grazing conditions as well as the stability of the mixtures over time.