Response of an Irrigated Cool- and Warm-Season Grass Mixture to Nitrogen and Harvest Scheme

Maintaining a mixture of cool-and warm-season grasses under intensive management for season-long production is difficult, due to species shifts, especially to a dominance of cool-season grasses when heavy amounts of nitrogen (N) fertilizer are used. The objective of this study was to determine if high forage yields could be produced season long while maintaining a desirable balance of warm-and cool-season grasses. The study was conducted near Mead, Nebraska on a Sharpsburg silty clay loam (Typic Argiudoll). An irrigated mixture of 3 warm-season grasses and 1 cool-season grass, big bluestem (Andropogon gerardii Vitman), switchgrass (Panicum virgatum L.), and indian-grass [Sorghastrum nutans (L.) Nash] and smooth brome (Bromus inermis Leyss.) was fertilized at low (150 kg/ha), medium (250 kg/ha) and high (350 kg/ha) rates of N in split applications. Three harvest schemes were designed to either produce high quality forage or to maximize yield. Herbage yields showed a quadratic response with N level. A late May/mid July harvest scheme for the first and second cuttings did not produce as much forage as late May/late August or early June/late August harvest schemes. Population of smooth brome and other cool-season grasses declined with the higher N rates. Populations of warm-season grasses were not greatly affected by N level. Density of smooth brome increased under all harvest scheme treatments and the highest increase for other cool-season grasses was with a May 24/July 13 harvest scheme. Warm-season grasses maintained a steady density over the 3 years. Forage was produced from early May until late summer with an irrigated cool- and warm-season mixture. Fall production of smooth brome was minimal, although stand was generally maintained. Nitrate N accumulated in the soil under the medium and high N treatments.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information.Migrated from OJS platform August 202