Search

Switchgrass (Panicum virgaum L.) is a warm-season (C4) perennial grass and a potential bioenergy crop. On-farm switchgrass field scale trials, which were initiated to obtain economic production information for switchgrass grown as a bioenergy crop in the northern Plains, provided information on establishment year stands and post-establishment year yields and stands both within and across fields and were used to determine if a stand threshold exists for switchgrass grown as a biomass energy crop. Switchgrass was seeded in 10 cropland fields, ranging in size from 3 to 9.5 ha, in Nebraska, South Dakota, and North Dakota in 2000 and 2001. The fields were selected to be representative of their region and eligible for the Conservation Reserve Program (CRP). Twelve sites within each field were geo-referenced, and switchgrass stand frequency was measured at each sample site. Biomass yields were estimated in late summer at the same within-field sites using a clipped quadrat. Fields with low initial switchgrass stand frequencies showed a linear relationship between initial switch-grass stands and second year stands and biomass yields. Results from the 10 field, three-state study indicated that establishment year stand frequency level of 40% or greater, determined by a frequency grid, can be considered an establishment year stand threshold for establishment success and subsequent post-planting year biomass yields for switchgrass. An establishment year stand frequency of 25% would be adequate for a switchgrass conservation planting in which no harvests would be planned for several years. [ABSTRACT FROM AUTHOR]

Quantifying toot structure response to multiple defoliation events in a grazing situation is critical in developing management plans for warm-season tallgrasses. A pasture experiment was conducted in 1999, 2000, and 2001 near Mead, NE. The objective of the experiment was to determine the effect of timing and frequency of grazing on big blue- stem (Andropogon gerardii Vitman) etiolated tiller growth and root and rhizome structure Paddocks were grazed at a stocking rate of 9.9 Animal Unit Month (AUM) ha-1 in two to tour cycles from mid-May to early-September. In April 2002, five 6.6- × 132-cm soil cores were extracted from each paddock. Soil cores were subsampled at 30-cm depth increments for estimates of root mass, root surface area, and root volume. Etiolated tiller tents were used to estimate organic reserves of big bluestem in each paddock in spring 2002. Mean number and weight of etiolated tillers were reduced by up to 40% and 50%, respectively, in paddocks grazed in a sequence of June after internode elongation, early August, and early September. Root structure in the top 30 cm of the soil profile was affected most by multiple defoliation events with <40 d of recovery between grazing periods. Root mass decreased by 25%, while mean surface area and volume of roots declined 10 and 15%, respectively, in the upper 30 cm of the soil profile in paddocks grazed in the sequence of post-internode elongation in June, early-August, and early-September. To maintain vigorous big blue-stem pastures, grazing management should concentrate on the elongation and postelongation periods. Grazing at the elongation stage should be rotated among paddocks in successive years and the recovery period following grazing at internode elongation should be >40 d. [ABSTRACT FROM AUTHOR]

Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] use as a turf in the northern USA is limited to a certain extent by its extended winter dormancy. A mixture of buffalograss with cool-season turf-grasses might extend the turf's green appearance and enhance quality. Research was conducted to determine the effects of overseeding fine- leaved fescue (Festuca spp.) in buffalograss turf on turfgrass color and quality and the effects of species, seeding rate and date, and core cultivation on fine-leaved fescue establishment in buffalograss turf. Hard rescue (F. longifolia Thuill.), blue rescue (F. ovina L. var. glauca Lam.), and Chewings rescue (F. rubra L. ssp. commutata Gaud.); seeding rates (10, 20, and 30 g m-2); seeding dates (fall, spring, or split fall-spring); and core cultivation (single or double pass).were evaluated for species composition, turfgrass quality, color, and green cover at the John Seatun Anderson Turfgrass Research Facility located near Mead, NE. Buffalograss turf overseeded with blue rescue in fall had the highest turfgrass quality, color, and green cover ratings. Fall overseeding resulted in the highest shoot density values. Spring overseedings were below acceptable levels. Botanical composition of the mixfures overseeded in fall reached 75 to 80% rescue and 20 to 25% buffalograss after 2 yr. Seeding rate effect was linear with each increment between 10 g m-2 and 30 g m-2 increasing fine-leaved rescue shoot density, tudgrass quality, color, and green cover. Blue fescue- buffalograss mixtures overseeded in the fall exhibited 80% green cover when buffalograss was dormant. Turfgrass green cover in the mixture was extended by 2 months when compared to buffalograss monostands growing in areas adjacent to the study. The results of this study support the use of fine-leaved rescue and buffalograss mixtures to extend turfgrass green appearance and enhance quality. [ABSTRACT FROM AUTHOR]