The Effect of Variable Seed Rate Proportions on Agronomic Attributes, Dry Matter Production, Biological Potential and Economic Viability of Some Grass-Legume Mixed Pastures
An experiment was conducted to assess the agronomic attributes, dry matter (DM) yield, biological potential and economic viability of grass-legume mixtures at Haramaya University in Ethiopia during 2004 and 2005. Chloris gayana, Panicum coloratum, Melilotus alba and Medicago sativa were planted as pure stand and in mixtures using 50:50, 33: 67, 67: 33, 25: 75 and 75: 25 seed rate proportion to give 24 treatments in a randomised complete block design with 3 replications. There were significant (P < 0.05) differences in the number of seedlings per m2 (SLM), row cover, number of tillers per m2, days to 50% flowering (DF 50%) of the grass components among the grass/legume combinations due to seed rate proportions. Moreover, SLM, the number of branches per m2, the height of the plant at harvest, DF 50% of the legume components were significantly (P < 0.05) affected among the mixtures due to seed rate proportions. There was a significant (P < 0.05) difference in the DM yield of pure stand grasses and legumes, and their mixtures due to seed rate proportion. Significant (P < 0.05) effects were also observed on the relative yield (RY), the relative total yield (RTY), the relative crowding coefficient (RCC) and the aggressivity index of both the grass and legume components and their mixtures due to different seed rate proportions throughout the study. The two years\' mean RTY of all grass-legume mixtures were greater than one (range: 1.23-2.11) and Chloris mixed with Melilotus and Medicago with 67: 33 seed rate proportion had higher RTY than other mixtures. Both the grass and legume components in the mixture produced mean RCCs values in excess of unity and almost equal values in both components, indicating that all yielded better in the mixture than expected in pure stands at different seed rates. Chloris gayana mixed with Melilotus alba at 50:50 and 33:67 seed rate proportion gave higher DM yield, average net return/ha and average net return/ha/yr compared to pure stand grasses and legumes and their different mixtures during the study. Therefore, to alleviate the feed scarcity in the area; these grass-legume mixtures could be introduced to smallholder farms. In addition, further studies on animal performances should be conducted using feeding trials and under grazing conditions.
Keywords: Agronomic Attributes; Biological Potential; Dry Matter Yield; Economic Viability; Grass/Legume Mixture; Seed Rate Proportion
East African Journal of Sciences Vol. 2 (2) 2008: pp. 95-104
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