Productivity and botanical composition of orchardgrass–white clover swards in a cool‐temperate hill land region of the eastern United States

Abstract

Understanding the growth dynamics of grass–legume swards is critical as pastoral management practices are adapted to varying economic constraints and emerging environmental considerations. Efficient management must synchronize the use of accumulated herbage with the needs of grazing livestock. This must be accomplished against the dynamic background of within and among year weather patterns interacting with herbage growth and grazing animal behavior. In the Appalachian region of the eastern United States, pastures often are dominated by orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.). We determined botanical composition and herbage productivity of orchardgrass and white clover swards during four consecutive years when managed as a function of canopy development and regrowth interval. Productivity was influenced by defoliation practices when mixtures were managed according to canopy development. Productivity was greatest when swards were managed as hay or when clipped to a 5‐cm residue each time mean canopy height reached 20 cm. White clover declined and orchardgrass increased in the sward irrespective of defoliation treatment. Botanical composition of mixtures with the erect growing orchardgrass tended to be more stable, whereas swards including the decumbent orchardgrass tended to be invaded by weeds. Some increase in productivity occurred during the first growing season when mixtures were clipped at either 2‐ or 4‐week intervals. Regardless of defoliation practice, white clover, and in some instances orchardgrass, presence declined during two consecutive growing seasons with various other volunteer grasses and forbs contributing to productivity. Productivity and persistence of sown sward components may be less dependent on management practices than on the expression of interactions responding to within and among year weather patterns.

Conditions that favor clover establishment in permanent grass swards

“…White clover populations also can vary unpredictably each year even under management practices that may benefit its persistence (Belesky and Fedders ; Malinowski et al . ).…”

“…Clover seedling densities were comparable to this study, but subsequent clover biomass was much higher eventually exceeding 25% of the total yield. While many factors affect clover establishment, abundant spring rainfall appears to be a necessary prerequisite (Vinther 2006;Black et al 2009;Malinowski et al 2012).…”

“…It also should be noted that large-leaved white clovers, like 'Kopu II' used in this study, may not persist well under stressful conditions compared with smaller leaved clovers (Black et al 2009). White clover populations also can vary unpredictably each year even under management practices that may benefit its persistence (Belesky and Fedders 1995;Malinowski et al 2012).…”

Designed and naturalised sward response to management: I. Patterns of herbage production

“…Swards comprising these species can be a result of intentional pasture renovation efforts, but a more likely scenario is that swards are a combination of sown and volunteer species occurring from past and current management practices interacting with microsite conditions within a given farm (Belesky et al, ). Previous work suggests that environmental conditions and time appear to have a greater influence than management practices, such as canopy use or nutrient input on sward productivity and composition (Archer & Smeins, ; Belesky et al, ; Jones, Alpuerto, Tracy, & Fukao, ; Malinowski et al, ; Marriott, Fothergill, Jeangros, Scotton, & Louault, ). Diverse swards could be used to exploit niche complementarity and interspecific interactions (Finn et al, ; Sanderson et al, ); however, it seems no simple management approaches can be recommended to create and sustain a particular sward composition.…”

“…This is likely in extensively managed hill‐land pasture where harvesting and storing forage may be problematic. Grass‐legume or grass‐legume‐forb forage mixtures buffered variation in productivity associated with growing conditions and microsite, where sward composition changed, while productivity did not (Belesky et al, ; Malinowski, Belesky, Ruckle, & Fedders, ). Forage communities with sustained productivity could provide a measure of stability in hill‐land terrain, where spatial and temporal microsite variability complicates production patterns (Belesky et al, ; Deak, Hall, Sanderson, & Archibald, ).…”