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ARS Home » Pacific West Area » Dubois, Idaho » Range Sheep Production Efficiency Research » Research » Publications at this Location » Publication #159940
Title: QUANTIFYING THE IMPACT OF A WEED IN A PERENNIAL RYEGRASS (LOLIUM PERENNE) WHITE CLOVER (TRIFOLIUM REPENS) PASTURE

Author
item Seefeldt, Steven
item STEPHENS, JONATHAN - UNIVERSITY OF WAIKATO
item VERKAAIK, MICHELLE - AGRESEARCH
item RAHMAN, ANIS - AGRESEARCH

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2004
Publication Date: 3/10/2005
Citation: Seefeldt, S.S., Stephens, J.M.C., Verkaaik, M.L., Rahman, A. 2005. Quantifying the impact of a weed in a perennial ryegrass-white clover pasture. Weed Science. 53:113-120.

Interpretive Summary: In a pasture are all weeds bad? The purpose of this study was to determine if individual plants of six different broadleaf plants reduced the productivity of the pasture. Plant biomass was measured under (W-zone), near (R-zone), and 1m away (control) from the rosettes of 6 different weed species before and after grazing. These measurements were taken throughout the growing season. The larger weeds, bull thistle and musk thistle reduced the amount of available forage 42 and 72%, respectively, in sheep grazed hill-country pastures. Forage production under and near Canada thistle and hedge mustard in a dairy pasture was slightly greater (136 and 140%, respectively) than in the control areas, whereas under broadleaf plantain and hairy buttercup forage production was significantly greater (178 and 450%, respectively). Although the dairy pasture was grazed following recommended grazing procedures, our results indicate that this grazing system was not maximizing yield potentials, and that these weeds served as an indicator that the pasture was being overgrazed.

Technical Abstract: In improved pastures any plant that is not from a sown seed is often labeled a weed. This is especially true for broadleaf plants. In New Zealand most improved pastures are a mix perennial ryegrass and white clover. Many of these pastures have broadleaf weeds, but little research has been conducted to determine the impact of these plants on pasture productivity. The impact of individual weeds on the pasture were determined using measurements of pasture productivity before and after grazing by dairy cattle or sheep under, near, and far from individual plants of six rosette-forming weed species throughout a growing season. The larger weeds, bull thistle (Cirsium vulgare) and musk thistle (Carduus nutans) reduced the amount of available forage 42 and 72%, respectively, in sheep grazed hill-country pastures. Forage production under and near Canada thistle (Cirsium arvense) and hedge mustard (Sisymbrium officinale) in a dairy pasture was slightly greater (136 and 140%, respectively) than in the control areas, whereas under broadleaf plantain (Plantago major) and hairy buttercup (Ranunculus sardous) forage production was significantly greater (178 and 450%, respectively). Although the dairy pasture was grazed following recommended grazing procedures, our results indicate that this grazing system was not maximizing yield potentials, and that these weeds served as an indicator that the pasture was being overgrazed.