Evaluation of Irrigated Tall Fescue–Legume Communities in the Steppe of the Southern Rocky Mountains

Abstract

Producers in the irrigated steppe of the southern Rocky Mountains are seeking ways to improve the summer productivity of their established cool‐season grass pastures, commonly tall fescue (Festuca arundinacea Schreb.). From 1994 to 1997, a study was conducted under irrigation at the New Mexico State University Alcalde Sustainable Agriculture Science Center, in which dry matter yield of monoculture tall fescue was compared with that of swards containing tall fescue in mixtures with alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), cicer milkvetch (Astragalus cicer L.), and kura clover (Trifolium ambiguum M.B.) in a randomized complete block design with three blocks. Percent tall fescue in the sward and the yield of tall fescue in mixtures declined from 1994 to 1996 and then increased in all mixtures except tall fescue–kura clover in 1997. Dry matter yields of alfalfa and cicer milkvetch increased until 1996 then declined, while birdsfoot trefoil equilibrated in 1996 and 1997 and kura clover continued to increase. Combined dry matter yields followed a trend similar to that of the legume yields except that, in 1996 and 1997, yields of the tall fescue–cicer milkvetch mixture were comparable to those of monoculture tall fescue, which were 5.76 and 6.72 Mg ha−1 for 1996 and 1997, respectively. Over the life of the study, tall fescue–cicer milkvetch yielded less than one‐half that of tall fescue–alfalfa while mixtures of tall fescue with birdsfoot trefoil or kura clover were equal to each other and intermediate to the others.