Performances of legume-grass mixtures under different cutting managements in mediterranean environments

摘要

Annual forage crops have great importance for sustaining animal production in southern Italy. Knowledge of the performance of legume-grass associations under management similar to systems encountered in farm practice is essential for their effective exploitation of the available environmental resources. The purpose of this investigation was to estimate the effects of five cutting managements on the productivity and botanical composition of ten annual fodder crop mixtures in two Mediterranean environments. Ten ternary combinations of one grass (Avena sativa L., oat and Lolium multiflorum Lam., Italian ryegrass), one clover (Trifolium alexandrinum L., berseem; Trifolium incarnatum L., crimson and Trifolium squarrosum L., squarrosum) or burr medic (Medicago polymorpha L.) and common vetch (Vicia sativa L.) were compared in a field trial (split-plot design, 3 replicates) in two locations (Cagliari and Foggia, Italy) during the 2000-2001 growing season. The cutting treatments included a winter grazing simulation (G), a cutting only regime at early (EF) or late flowering (F) of legumes and a combination of treatments (GEF and GF). Plant density (no. m-2) prior to cutting, dry matter yield (g m-2) and botanical composition (%) were evaluated. Considerable differences were observed in the harvestable dry matter yields of mixtures among cutting treatments in both localities, with treatment F showing the higher values (787.1 and 415.7 g m-2 for Cagliari and Foggia, respectively). The forage species were able to compete and establish good growth during their initial phase in both localities. However, the botanical composition between the two sites differed considerably after the winter period. Particularly, at Foggia, grass dominance was a permanent feature of all treatments, and all the mixtures contained about 84% of grass. Italian ryegrass was the most representative species under all treatments in both sites. Mixtures with Italian ryegrass, crimson or berseem clovers and vetch showed higher adaptability to cutting treatments particularly at Cagliari. Our results showed that the forage species associations studied can be grown successfully under simulated grazing treatment during the winter season and under the double land-use system (integrated grazing and cutting) adopted at Cagliari. These treatments provide a reasonably economical means of assessing mixtures under diverse farming conditions. However, as a fraction of the plant population in swards of this experiment diminished over time, particularly at one site, the optimum of species present in these forage species associations have yet to be determined.