Herbage production of red clover cultivars in mixtures with perennial ryegrass and prairie grass under grazing.

摘要

In Balcarce (37degree C45' South, 58degree C18' West), Argentina, an experiment was conducted for 2 years to determine net herbage accumulation (NHA) of red clover (Trifolium pratense) cultivars in mixtures with grasses under grazing. Eight treatments were established: four red clover cultivars (Redland II = RED; Estanzuela 116 = EST; Flare = FLA; and EI Sureno INTA = SUR) were grown in mixtures with perennial ryegrass (Lolium perenne) (PR) or with prairie grass (Bromus willdenowii [B. catharticus]) (PG). Treatments were applied in a factorial arrangement with a randomized complete block design and three replications. When pastures reached 5.9 to 7.9 in. high they were grazed down to 2 in. by dairy cows in 3 days. In the first year, NHA of sown species with PRwas higher than that with PG (6712 vs. 5993 lb/acre, P<0.05). The NHA of red clover with PG was higher than that with PR mixtures (2765 vs. 1324 lb/acre, P<0.01) and NHA of SUR was superior to EST and FLA (P<0.05). In the second year the NHA of sown species with RED and FLA treatments was greater than with EST and SUR (11177 vs. 8088 lb/acre, P<0.01). The NHA of red clover with RED and FLA was higher (9335 lb/acre) than for EST and SUR (5815 lb/acre, P<0.01). Consequently, in the first year PR-red clover mixtures produced more herbage from sown species than PG-red clover mixtures, but with lower red clover contents. In the second year, the contribution from grasses was greatly reduced. Compared with EST and SUR mixtures, the NHA for RED and FLA was 40%greater. The NHA ranking of red clover cultivars was not altered by the associated grass species.