Submitted to: Forage and Grazinglands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 21, 2013
Publication Date: June 21, 2013
Citation: Bartholomew, P.W. 2013. Productivity of annual and perennial cool-season grasses established by no-till overseeding or by conventional tillage and sowing. Forage and Grazinglands. doi:10.1094/FG-2013-0621-01-RS. Interpretive Summary: In the southern Great Plains (SGP) cool-season grasses can provide a supply of feed for grazing livestock during periods of the year when temperatures are too low to allow active growth of warm-season crops. Cool-season perennial grasses such as tall fescue may be preferred to annual species because their presumed ability to regenerate year after year avoids the risk and cost of replanting that is necessary with annual grasses. However, in limited resource, low-productivity farming systems previous work has found that perennial cool-season species have limited ability to persist from year to year and this reduces their lifetime productivity so that the yield gain may be insufficient to justify the costs of planting. Some of the problem of lack of persistence arises from the very high temperatures and low moisture conditions characteristic of the summer months in the SGP. Recently varieties of tall fescue that may be better adapted to these conditions have been identified (Grasslands Flecha and Texoma MaxQII), and their performance was tested in comparison with a long-term standard variety of tall fescue (Kentucky 31) and with a widely-used variety of annual ryegrass (Marshall). These grasses were tested in combination with conventional and no-till methods of establishing cool-season grasses. Over three years and in two experiments annual ryegrass was the most productive of cool-season grasses tested. Texoma MaxQ II was more productive than K31, which was in turn more productive than Flecha. Neither Texoma MaxQII nor Flecha was significantly more persistent than K31. Warm- and cool-season total production of grass was greatest when annual ryegrass was no-till overseeded on existing warm-season pasture. When existing warm-season pasture was tilled prior to sowing cool-season grass there was a net reduction in year-round grass production, because the yield obtained from cool-season grass was not sufficient to compensate for the loss of production from warm-season grass.
Technical Abstract: In the southern Great Plains (SGP), perennial pasture grasses offer a source of cool-season forage that does not incur costs and risks associated with production of annual cool-season forages. However, persistence and lifetime productivity of perennial cool-season grasses may be compromised by the high temperatures and soil moisture deficits common in the summer months in the SGP. Tall fescue (TF) cv Texoma MaxQII (TMQ), Flecha (FLE) and Kentucky 31 (K31) and annual ryegrass cv Marshall (IRG) were no-till overseeded into existing unimproved warm-season pasture or were sown into a tilled seedbed. Effects of cultivar and establishment method on pasture production and persistence of tall fescue were evaluated. Tillage prior to planting increased cool-season grass yield, compared with no-till overseeding, but the effect on total annual forage production was generally negative. TMQ was the most productive of TF cultivars tested with a mean increase of 53% over K31. Limited persistence of TF, including summer-dormant FLE, reduced lifetime productivity of perennial cool-season pasture, compared with annual ryegrass, which produced the greatest 3-year total yield of cool-season grasses tested. The total yield over 3 years of unmodified warm-season pasture was only surpassed on treatments where IRG was overseeded into existing warm-season pasture.