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United States Department of Agriculture

Agricultural Research Service

Title: Growth, Water Relations and Nutritive Value of Pasture Species Mixtures under Moisture Stress

Authors
item Skinner, Robert
item Gustine, David
item Sanderson, Matt

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 27, 2004
Publication Date: July 1, 2004
Citation: Skinner, R.H., Gustine, D.L., Sanderson, M.A. 2004. Growth, water relations and nutritive value of pasture species mixtures under moisture stress. Crop Science. 44:1361-1369.

Interpretive Summary: A primary goal of grazing land managers in the northeastern USA is to improve forage production during summer months when heat and moisture stress limit growth of cool-season forages. Pastures in the northeastern USA typically are dominated by Kentucky bluegrass and white clover. Both dominant species are sensitive to water deficits and elevated temperatures, providing only limited forage during summer months. Evidence suggests that pasture productivity under harsh environments can be increased by increasing species diversity. This research compared a two-species mixture containing the relatively drought tolerant orchardgrass and red clover, and two five-species mixtures with the typical white clover and Kentucky bluegrass mixture which is predominant in northeastern USA pastures. The five-species mixture containing chicory, orchardgrass, Kentucky bluegrass, perennial ryegrass and white clover had the greatest dry matter production at all moisture levels. Increased yield was primarily due to the robust growth of chicory which dominated the mixture. In addition, white clover growing in the mixture with chicory had improved leaf water relations and greater relative growth rates than white clover growing with Kentucky bluegrass. Inclusion of the deep-rooted species, chicory, appeared to be more important than increasing the number of species in improving productivity under stressful environments.

Technical Abstract: Evidence suggests that pasture productivity under harsh environments can be increased by increasing species diversity. This research was conducted under two large (10.2 x 26.8 m) rainout shelters combined with a drip irrigation system to provide deficit, normal and excessive moisture conditions. A two-species (simple) mixture containing the relatively drought tolerant species, orchardgrass (Dactylis glomerata L.) and red clover (Trifloium pretenseL.) and two five-species (complex) mixtures were compared with a simple mixture containing the drought sensitive species white clover (Trifolium repens L.) and Kentucky bluegrass (Poa pratnesis L.) which are the predominant species in northeastern USA pastures. Plots were clipped from mid-May to early-October in 2000 and 2001 on a schedule that mimicked management-intensive grazing practices. The complex mixture containing chicory (Cichorium intybus L.), orchardgrass, Kentucky bluegrass, perennial ryegrass (lolium perenne L.) and white clover had the greatest dry matter production at all moisture levels. Yield in that mixture was increased by 89% in the dry, 61% in the normal and 43% in the wet treatments compared to the white clover-Kentucky bluegrass mixture. Increased yield was primarily due to the robust growth of chicory which dominated the mixture, accounting for 71% of harvest biomass by the fall of 2001. In addition, white clover growing in the mixture with chicory had improved leaf water relations and greater relative growth rates than white clover growing in the simple mixture. Inclusion of a deep-rooted functional type appeared to be more important than species richness, per se, in improving productivity under stressful environments.

Last Modified: 4/24/2014
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