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© 2004 Plant Management Network.
Accepted for publication 6 February 2004. Published 18 March 2004.

Forage Yield and Nutritive Value of Selected Quackgrass

Craig C. Sheaffer, Nancy J. Ehlke, Donald L. Wyse, Donne J. Vellekson, Douglas R. Swanson, and J. L. Halgerson, Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul 55108; and R. D. Mathison, North Central Research and Outreach Center, Grand Rapids, MN 55744

Corresponding author: Craig C. Sheaffer. sheaf001@umn.edu

Sheaffer, C. C., Ehlke, N. J., Wyse, D. L., Vellekson, D. J., Swanson, D. R., Halgerson, J. L., and Mathison, R. D. 2004. Forage yield and nutritive value of selected quackgrass. Online. Forage and Grazinglands doi:10.1094/FG-2004-0318-01-RS.

Abstract

Quackgrass (Elytrigia repens (L.) Desv. ex Nevski) is a widely distributed perennial that colonizes pastures and hayfields in the northern USA and is often considered a weed. Recently, the first quackgrass cultivar, Everett, was released for use in soil conservation. Our objective was to compare the forage yield and nutritive value of Everett quackgrass, common quackgrass, and a leafy quackgrass selection with orchardgrass (Dactylis glomerata L.) and reed canarygrass (Phalaris arundinaceae L.) when each was grown in pure stands and mixture with alfalfa (Medicago sativa L.). Nitrogen fertilized grass and grass-alfalfa mixtures were harvested three times per year for 3 year at St. Paul and Grand Rapids, MN. Yields of quackgrass entries were similar and averaged 5.0 and 2.2 tons/acre at St. Paul and Grand Rapids, respectively, while reed canarygrass yielded 5.4 and 2.8 tons/acre at these same locations. Forage yield of quackgrass-alfalfa mixtures was similar to or exceeded yield of reed canarygrass- or orchardgrass-alfalfa mixtures each year. Quackgrass entries had similar yields in mixtures and contributed an average of 42 and 33% to mixture yield at St. Paul and Grand Rapids, respectively. Nutritive value of quackgrass was similar to reed canarygrass and was sometimes higher than that of orchardgrass. Quackgrass is a valuable forage crop and the availability of seed of Everett quackgrass will allow promotion of its use for soil conservation and forage.

Introduction

Quackgrass is a cool-season perennial grass that is noted for aggressive spreading by rhizomes and persistence. It is considered a noxious weed in cropping systems and can reduce the yield of row crops and the quality of forage crops like alfalfa (4,8). However, quackgrass is adaptable to a range of environments and management regimes and often becomes the predominant grass in hay fields, pastures, and set-aside fields in the northern USA (1,7). Native stands of quackgrass are often harvested for forage. In Minnesota and Wisconsin, quackgrass plants with diverse morphological traits were selected from wild populations growing on agricultural lands (3,6,11,13). These plants differed in forage yield and nutritive value but some had yield and nutritive value similar to cultivated grasses such as reed canarygrass and smooth bromegrass (Bromus inermis Leyss.) (3,10,11). In Wisconsin, highly rhizomatous quackgrass populations had forage yields that were similar to the average yield of a diverse group of orchardgrass, tall fescue (Festuca arundinaceae Schreb.), and timothy (Phleum pratense L.) cultivars (2).

Recently, Everett quackgrass, a cultivar selected for high rhizome production, was released for use in land stabilization and reclamation (15). A leafy and high yielding population of quackgrass (designated as "Hi-For") has also been selected (N. J. Ehlke, personal communication). The forage yield and nutritive value of these quackgrasses has not been compared to that of orchardgrass and reed canarygrass when subject to three-cut schedules used for hay production in the north-central USA. Our objective was to determine the forage yield and nutritive value of Everett, Hi-For, and common quackgrass compared to reed canarygrass and orchardgrass when grown in pure stands and mixture with alfalfa.

Research Design

Research was conducted from 1996 to 1998 at St. Paul in east-central Minnesota on a Waukegan silt loam (fine-silty over sandy, mixed Typic Hapludoll) and at Grand Rapids in northern Minnesota on a Cowhorn very find sand (coarse-loamy, mixed nonacid Aeric Haplaquept) with pH, P, and K levels greater than 6.5, 60 lb/acre, and 300 lb/acre, respectively. Split applications of N fertilizer (total of 150 lb/acre annually), including 50 lb/acre in April and immediately after the first and second harvests, were applied to the pure grass stands.

A randomized complete block design with four replicates was used. Treatments were three quackgrasses, Palaton reed canarygrass, and Orion orchardgrass. The quackgrasses were: Everett, a released cultivar; Hi-For, a population selected for high forage and low rhizome yield; and a common, naturally seeded quackgrass collected from northern Minnesota. The grasses were grown in pure stands and in mixture with Pioneer 5262 alfalfa. Plots were established in August 1995 in 6- by 20-ft plots. Quackgrass, reed canarygrass, and orchardgrass were seeded in pure stands at 10, 8, and 16 lb/acre, respectively. These same grasses were seeded at 5, 5, and 8 lb/acre, respectively, in mixture with alfalfa that was seeded at 7 lb/acre. Excellent stands of all forages (> 20 plants per ft²) were present in the spring of 1996 when cutting was initiated.

All plots were harvested three times per year at each location on about 1 June, 15 July, and 1 September at St. Paul and on 15 June, 25 July, and 18 September at Grand Rapids. At the first harvest each year, orchardgrass was headed and at anthesis, while the quackgrass and reed canarygrass were at early heading before anthesis. At subsequent harvests, grasses were vegetative with quackgrass and reed canarygrass having culm elongation. In mixtures, alfalfa was at early flowering at each harvest. Herbage yields were measured by cutting a 3- by 15-ft area within each plot to a 2-inch stubble height. Wet forage yields were adjusted to dry weight by drying a 1.5-lb subsample from each plot at 135°F to determine dry matter concentration. In 1996 and 1997, an additional 1-lb subsample was manually cut from each plot at harvest and dried at 135°F. The dried subsample was ground and analyzed for crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) concentration using near infrared reflectance spectroscopy (NIRS). Near infrared reflectance spectra were collected using a Pacific Scientific (NIRSystems, Silver Spring, MD) Model 6250 reflectance scanning monochromotor. A set of subsamples for calibration was selected by the SUBSET program (14) and analyzed for CP using the Kjeldahl procedure and for ADF and NDF (5). The wet chemistry results from the subsamples were used with the BEST program to calibrate NIRS for CP, NDF, and ADF. Standard errors of calibration for CP, ADF, and NDF were within acceptable limits and R2 values for all variables were greater than 0.95 indicating that NIRS equations effectively predicted forage nutritive value variables.

All data were subject to analysis of variance using SAS (9). Because of known differences in climate and yield potential between locations, the location by treatment interactions were not evaluated. Yield response to treatments was not consistent over years (a year by treatment interaction occurred) at both locations. Forage nutritive value data was averaged over cuttings each year and for 1996 and 1997 due to similar treatment responses over cuttings and years. Forage subsamples from each harvest were composited for the year using a weighted mean method that adjusts the quantity of each subsample added to the yearly composite based on the relative yield at each harvest.

Forage Yields

Grass yields were greater at St. Paul in east-central Minnesota than at Grand Rapids in northern Minnesota due to the longer growing season and higher growing season temperatures. For the 3-year study at St. Paul, quackgrass, orchardgrass, and reed canarygrass yields averaged 5.0, 5.0, and 5.4 tons/acre, respectively, while at Grand Rapids quackgrass, orchardgrass, and reed canarygrass averaged 2.2, 2.7, and 2.8 tons/acre, respectively. Within years, there were yield differences among species (Table 1). At St. Paul, forage yields were similar for the grasses in 1996 and 1997, but in 1998 yield of reed canarygrass exceeded those of all quackgrass entries and orchardgrass. In that year also, Hi-For quackgrass yielded more than Everett or common quackgrass. At Grand Rapids, all grasses had similar yields in 1998, but all quackgrass entries had lower yields than reed canarygrass or orchardgrass in 1996 and 1997. Previous research in Minnesota (11) and Wisconsin (2) found that diverse quackgrass populations often had similar forage yields.

Table 1. Dry matter yield (tons/acre) of quackgrass, reed canarygrass, and orchardgrass grown in pure stands and mixture with alfalfa at St. Paul and Grand Rapids, MN.

^x LSD, least significant difference at the P < 0.05 level.

^y NS: Means are not different, P = 0.05

^z Numbers in parenthesis are % grass composition of the mixture.

Forage yields of grass-alfalfa mixtures were also higher at St. Paul than at Grand Rapids. At St. Paul, mixture yields of quackgrasses were similar to or greater than for reed canarygrass each year. The alfalfa-orchardgrass mixture was consistently among the lowest yielding. There were no consistent differences in mixture yields among the quackgrass entries. Quackgrass entries had similar contribution to total mixture yield each year with average composition increasing from 38 to 46% from 1996 to 1998. Reed canarygrass and orchardgrass contributions to mixture yield were more consistent among years and averaged 35 and 55%, respectively.

At Grand Rapids, quackgrass, reed canarygrass, and orchardgrass mixtures had similar yield each year. Quackgrass entries had similar average mixture composition that increased from 33 to 40% from 1996 to 1998. During the same period, reed canarygrass composition decreased from 53 to 40%, while orchardgrass composition increased from 63 to 80%. Sheaffer et al. (10) also reported that orchardgrass became a dominant component of mixtures with alfalfa, whereas reed canarygrass was less competitive than orchardgrass and contributed 35% of the mixture DM.

Yields of N-fertilized grass monocultures were not consistently different from those of grass-legume monocultures. Sleugh et al. (12) reported that alfalfa-orchardgrass mixtures yielded more than pure stands of orchardgrass; however, they fertilized orchardgrass with only 60 lb of N per acre, a practice that likely limited its yield potential compared to our application of 150 lb of N per acre.

Nutritive Value

Nutritive value of quackgrass forage was similar to that of reed canarygrass and sometimes was greater than orchardgrass at both locations (Table 2). Quackgrass entries had similar nutritive value. Nutritive value was likely influenced by maturity of the grass at harvest as orchardgrass was somewhat more mature. These results agree with those of Sheaffer et al. (11) who reported that quackgrass biotypes did not consistently differ in nutritive value and were similar to reed canarygrass and smooth bromegrass.

Table 2. Crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF), as a percent of dry matter, of quackgrass, reed canarygrass, and orchardgrass at St. Paul and Grand Rapids, MN.

^x LSD, least significant difference at the P < 0.05 level.

^y NS: Means are not different, P = 0.05

Mixtures of grasses with alfalfa had higher CP and lower fiber than grass monocultures likely because of the higher CP and lower fiber of the alfalfa component relative to grasses. The orchardgrass mixture with alfalfa had the highest grass concentration and was among the grasses with the highest fiber concentration and the lowest CP concentration at both locations. Sheaffer et al. (10) previously reported that grass composition was positively correlated with forage NDF concentration of perennial grass-alfalfa mixtures but not consistently correlated with CP or in vitro dry matter digestibility. Other authors have reported that forage of alfalfa-grass monocultures had greater forage digestibility, CP concentration, and reduced NDF concentration compared to grass monocultures (12).

Conclusions

Although quackgrass is often regarded as a weed, it should be considered as a cultivated hay crop either in N-fertilized pure stands or in mixture with alfalfa in the north-central region. It should not be eradicated to establish other grasses such as orchardgrass and reed canarygrass. When subjected to a three-harvest hay management system, pure stands of quackgrass had similar nutritive value as reed canarygrass but somewhat lower yield. Quackgrass had similar yield as orchardgrass, but its nutritive value was sometimes higher. Its contribution to mixtures with alfalfa was similar to that of reed canarygrass and it was less dominant than orchardgrass. Although selected for different traits, quackgrass entries did not consistently differ in yield or nutritive value. Availability of seed of the newly-released cultivar Everett should aid in planned use of quackgrass as a forage crop and for soil conservation. Everett quackgrass should also be valuable for use in pastures; however, research is warranted on its yield and persistence under grazing. Seed is available for sale in Minnesota by Norfarm Seeds, Inc. Roseau, MN.

Literature Cited

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15. Wyse, D. L., Sheaffer, C. C., Ehlke, N. J., Swanson, D. R., and Vellekson, D. J. 2003. Registration of ‘Everett’ quackgrass. Crop Sci. 43:433.