Forage Yield of Grass-alfalfa and Grass-forage Kochia Mixtures on Semiarid Rangelands

摘要

Increased productivity of semiarid western United States grazing lands is possible with appropriate plant materials. This study compared late summer forage yield of ‘Vavilov’ Siberian wheatgrass (Agropyron fragile) and ‘Mustang’ Altai wildrye (Leymus angustus) in binary mixtures with two alfalfas (Medicago sativa) and two forage kochias (Kochia prostrata) at plant densities on 0.25, 0.5, 0.75, and 1.0-m centers. At the 0.25-m spacing, yield of the Vavilov and Mustang monocultures were 1.34 and 1.12 Mg/ha, respectively. Mustang-alfalfa yields were 11% higher than Mustang monocultures. Vavilov-alfalfa yields were 36% higher than Vavilov monocultures, and 45% higher than the Mustang-alfalfa mixtures. Yield of grass-forage kochia mixtures ranged from 1.78 to 3.89 Mg/ha at the 1.0 and 0.25-m spacings. The increase in yield of these mixtures over grass monocultures was 94% at the 1.0-m spacing to over 200% at the 0.25-m spacing. Mixtures with S-Select forage kochia at all spacings were the highest yielding. Although each mixture contained equal plants of each species, the contribution of each to overall yield was different. In grass-kochia mixtures, the kochia component averaged 79% of the total yield, whereas in the grass-alfalfa mixtures, the alfalfa component varied from 23 to 73%. Revegetated rangelands with forage kochia or a legume such as alfalfa will have increased productivity.