Decade-long persistence, production, and profitability of tall fescue–alfalfa mixtures and nitrogen-fertilized tall fescue

Abstract

Concerns about forage crop productivity often focus on persistence. Research shows that binary grass–legume mixtures yield more than nitrogen (N)-fertilized grass monocultures. However, their long-term ability to sustain higher production and profits remains uncertain. To address this, a 10-year field study was conducted at the University of Wyoming James C. Hageman Sustainable Agriculture Research and Extension Center at Lingle, WY. The study evaluated forage accumulation, nutritive value, and profitability of tall fescue [Lolium arundinaceum (Schreb.) Darbysh.]–alfalfa (Medicago sativa L.) mixtures compared to N-fertilized tall fescue monoculture. The study comprised 10 treatments in randomized complete blocks with three replications: an alfalfa monoculture, three tall fescue–alfalfa mixtures (75:25, 50:50, and 25:75 seed ratios), and tall fescue monoculture fertilized with 0, 50, 100, 150, 200, and 300 kg N ha⁻¹ year⁻¹. The 50:50 mixture achieved the greatest total annual forage accumulation and was the most profitable ($67 ha⁻¹ year⁻¹). Despite 300 kg N ha⁻¹ year⁻¹-fertilized tall fescue achieving the highest total forage accumulation among monocultures, it was unprofitable ($36 ha⁻¹ year⁻¹). Tall fescue receiving 50–200 kg N ha⁻¹ year⁻¹ was profitable but less so than the mixtures and alfalfa monoculture. Over 10 years, the average annual forage nutritive value was highest for alfalfa monoculture, followed by the mixtures and N-fertilized tall fescue. Results indicate that the 50:50 mixture has great potential for long-term persistence, improved forage production, and profitability. We, therefore, recommend growers to consider cultivating 50:50 mixture under intensive management for successful forage production in the long term.