Over a five years period (1980-1985), at La Platina Research Station (INIA, Santiago), threo alfalfa varieties (Rayen, WL-512 and WL-514), established at fivesowing rates (10,15,20,25, arid 30 kg/ha), were evaluated. A split-plot design, in randomized blocks with four replications, was used. Fertilization at establishment was 52.4 kg P/ha and 16 kg N/ha. At the end of each season,a top dressing of 20.1 kg P/ha was applied. Main objectives of the experiment were to determine the effect of sowing rate, in each variety, over quality, persistance and dry matter yield. Results showed that differences in quality of the pasture, with similar regrowth, were higher dueto date of sampling than to treatments. Average crude protein leveis for sowing rates of 10, 20, and 30 kg/ha were 26.98% and 21.22%, for spring 1980 and autumn 1981, respectively. For the same sowing rates and dates, digestibility varied between 79.42% and 66.30%. For varieties, both crude protein and digestibility were as well higher in spring than in autumn. Density of the sward increased in a linear form (P < 0.01) with sowing rates, from stablishment up to 48 months after sowing; then, the sward entered a period of stabilization, to reach the end of the trial with and average of 37 plants/m2, with no differences between sowing rates. During the first season, only WL-514 showed a positive linear response in yield as sowing rate increased (P < 0.05), while WL-512 showed en inverse response (P < 0.01). Varieta! responses for the resi of the trial was quite variable. Atthe end of the experimental period,there were no significatives differences in yield,nor sowing rate x variety interaction, with an average total production, for al! treatments, of 82.56 Ton D.M./hectare, |
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