Herbage Productivity and Botanical Composition of Hill Pasture as a Function of Clipping and Site Features
Complex topography and varied soil of hill-land pastures create microsite conditions that support an array of floristic associations and herbage production patterns. This complicates management for forage and livestock production because the seasonal distribution and quantity of forage vary. Our objective was to determine herbage production and floristic composition of a hill pasture as a function of site characteristics and canopy management. An existing 3-ha hill pasture watershed was oversown with white clover (Trifolium repens L.) and orchard-grass (Dactylis glomerata L.) and fertilized with reactive phosphate (PO 4 ) rock (PR). Replicated plots on each of four sites were clipped once (stockpiled), twice (hay harvest), or three times (long rotation) annually. Site had a significant impact on cumulative herbage production, whereas the influence of clipping was mixed. The least (1.9 Mg ha -1 ) amount of herbage production in a given season occurred on a northeast (NE)-facing site and the greatest (4.6 Mg ha -1 ) in a natural drainage area (ND) traversing the pasture. Herbage production increased by about 80% with overseeding and PR, but the relative ranking of production among sites stayed the same. Botanical composition was also strongly influenced by site, with velvetgrass (Holcus lanatus L.) predominating in ND and red fescue (Festuca rubra L.) occurring primarily on the NE site. The stockpiled treatments became dominated by grasses and weeds 4 yr after treatments were imposed, regardless of site, and were similar to the least productive site (NE-facing) in the pasture. Our results suggest that application of amendments to the more productive portions of a site are likely to have greater return.
Grazing Schedule Effect on Forage Production and Nutritive Value of Diverse Forage Mixtures
The use of complex mixtures (mixtures of more than three species) may increase yield of pastures; however, we know little about how grazing management affects the productivity of mixtures. A grazing experiment was performed during 2005 and 2006 near State College, PA, to compare mixtures of grasses, legumes, and chicory (Cichorium intybus L.) for their botanical composition, nutritive value, and forage production under two grazing schedules: when the sward reached 25 cm in height (sward height schedule, SH) or when alfalfa (Medicago sativa L.) reached the bud stage (morphology or MP schedule). The SH schedule produced 30% more dry matter (DM) than the MP schedule averaged for 2 yr. Forage yield of the five-species (6427 kg ha -1 in 2005 and 6624 kg ha -1 in 2006) and seven-species (6816 kg ha -1 in 2005 and 6772 kg ha -1 in 2006) mixtures was stable during the contrasting weather of 2005 and 2006. Grass monoculture with N and simple mixtures (two species, grass-legume) produced 989 kg ha -1 more DM than the complex mixtures in 2006 when weather conditions were favorable. The SH schedule produced forage of better nutritive value compared with the MP schedule at first harvest in both years [20 g kg -1 less acid detergent fiber (ADF) in 2006; 25 g kg -1 in 2005, 53 g kg -1 in 2006 more neutral detergent fiber (NDF); 21 g kg -1 in 2005, 30 g kg -1 in 2006 more crude protein (CP); and 33 g kg -1 in 2006, 53 g kg -1 more in vitro true dry matter digestibility (IVTDMD)]. Complex mixtures of forage species provide more consistent yields of DM than binary grass-legume mixtures or grass monocultures in variable environments.
Leaf and tiller or stolon death of Lolium perenne, Agrostis spp., and Trifolium repens in set-stocked and rotationally grazed hill pastures
Abstract Leaf death rates, leaf longevity, and tiller and stolon death rates of Lolium perenne, Agrostis spp. and Trifolium repens were compared for one year on hill pastures which were set-stocked and rotationally grazed by sheep. Leaf death rates and leaf longevity were largely unaffected by grazing management, and the number oflive leaves per tiller or stolon did not differ greatly between managements. Agrostis spp. had more leaves per tiller than L. perenne. Leaf longevity was least in spring and summer when leaf death rates were fastest, and was greatest in winter when leaf death rates were slowest. In autumn, spring, and summer, mortality of leaves occurred within 3 weeks of their appearance, resulting in the loss of up to 28% of leaves which had been formed soon after one grazing before the next grazing under the rotational management. The long rotation in winter (63 days) resulted in the death of many leaves before they had a chance to be grazed. Leaf utilisation data showed that 20–46% of L. pere...