Browsing Journal of Range Management, Volume 52, Number 1 (January 1999) by Subjects
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Animal and plant response on renovated pastures in western CanadaExtending the present 4 month grazing season in the Aspen parklands of western Canada is of major economic interest to cow-calf producers. A long-term experiment was conducted on 375 ha to compare the present practice of continuous grazing with no fertilizer to a rotational grazing system of 4 paddocks fertilized in alternate years with 90 kg N, 45 kg P2O5, 10 kg S ha-1 and a 6 paddocks rotational grazing system including fertilizing and species replacement by cultivation and reseeding. Compared to the continuously-grazed control, the grazing period was extended by 14-days on the 4-paddock rotation system, and by a further 15-days on the 6-paddock rotation system, divided about equally between spring and fall. Forage yield, cow weight gains and calf growth were significantly improved, and year-to-year variation in forage yield and animal weight gain was reduced. In the 6-paddock rotation system, breaking 1 paddock at a time in summer after grazing, and reseeding the following spring caused no noticeable reduction in grazing capacity. Replacing the bromegrass (Bromus inermis Leyss.) dominated vegetation in 1 of the 6 paddocks with an early-growing grass contributed to the grazing season extension. Crested wheatgrass (Agropyron cristatum (L.) Gaertn.) performed well in this role; Russian wildrye (Psathyrostachys juncea (Fisch.) Nevski) died out within 6 years of seeding.
Effects of management on species dynamics of Canadian aspen parkland pasturesThe effects of grazing, fertilizing, and seeding on persistence of herbaceous species was monitored by point quadrat about every second year from 1975 to 1989 in a low-fertility pasture in the aspen parkland vegetation zone of east-central Saskatchewan, Canada. Ground cover response to continuous grazing was contrasted with that of 4- and 6-paddock rotationally-grazed areas fertilized in the fall of every other year with 90 kg N, 45 kg P2O5, 10 kg S ha-1. The original vegetation in 2 paddocks of the 6-paddock system was replaced with Russian wildrye (Psathyrostachys juncea (Fisch.) Nevski) in 1976, and in 1 of the other 4 paddocks in turn with smooth brome (Bromus inermis Leyss.)-alfalfa (Medicago sativa L.) in 1979 and 1981, crested wheatgrass (Agropyron cristatum (L.) Gaertn.) in 1983, and a meadow brome (Bromus riparius Rehm.)-alfalfa mix in 1985. Initially, smooth brome and creeping red fescue (Festuca rubra L.) dominated the vegetation with ground cover estimates of 10-20% and 40-60%, respectively. Alfalfa ground cover was less than 1%. With the changes in management, Kentucky bluegrass (Poa pratensis L.) replaced creeping red fescue. Alfalfa increased until 1980 and then declined to its original level, apparently in response to precipitation trends. Russian wildrye almost died out and was replaced by brome and Kentucky bluegrass. Reseeding with smooth bromegrass-alfalfa did not consistently increase brome ground cover beyond that obtained by rotational grazing and fertilization, and increased alfalfa only temporarily. Cultivation during the summer before spring seeding resulted in partial recovery of the old vegetation and invasion by Kentucky blue-grass. Total ground cover varied from year to year in response to spring precipitation. Forbs usually increased after reseeding, but declined to their original levels within 5 years.
Yield and feeding of prairie grasses in east-central AlbertaInformation on the yield of grasses as the plants mature is useful to optimize grazing potential and quality hay production. The objectives of this study were to compare the yield and feeding value of 11 common prairie grasses over 2 yearly cycles of growth and determine which of the grasses may require supplementation to meet nutrient requirements of grazing cattle. Dry matter yield (DM), crude protein (CP), acid detergent fiber (ADF), calcium (Ca), and phosphorus (P) values were obtained for brome (Bromus inermis [L.]), creeping red fescue (Festuca rubra [L.]), crested wheatgrass (Agropyron cristatum [L.] Gaertn), intermediate wheatgrass (Agropyron intermedium (host) Beauv), meadow foxtail (Alopecurus pratensis [L.]), orchardgrass (Dactylis glomerata [L.]), pubescent wheatgrass (Agropyron trichophorum Link. richt), streambank wheatgrass (Agropyron riparium Scriba &Smith), slender wheatgrass (Agropyron trachycaulum Link Malte), tall fescue (Festuca arundinacea Schreb), and timothy (Phleum pratense [L.]) at weekly intervals from June to September, in 1992 and 1993. Most grasses reached maximum yields at week 8 in 1992 (drought year) and week 12 in 1993 (normal year). Herbage mass yields (g/0.25m2 at week 8 in 1992 (highest to lowest yielding) were crested wheatgrass (235), intermediate wheatgrass(210), pubescent wheatgrass(173), brome(161), slender wheatgrass(152), meadow foxtail(114), Tall fescue(110), timothy(101), orchardgrass(83), creeping red fescue(56), and streambank wheatgrass(50). Herbage mass yields pattern of the grasses in 1993 was similar to that in 1992 except for crested wheatgrass and brome which ranked first and fourth in 1992 but ranked fifth and second, in 1993, respectively. Quality declined in all grasses as they matured. The average CP content of grasses declined from 24% to 13% in 1992 and from 21.5% to 12.1% in 1993 but were adequate to meet crude protein requirements of growing, pregnant or lactating grazing cattle. The Ca levels in all grasses were adequate for all classes of cattle on pasture but the low P levels of 0.11% in both years indicate that growing, pregnant or lactating cattle grazing on these pastures would require P supplementation.