Suppression of grasshoppers in the Great Plains through grazing management
AuthorOnsager, J. A.
twice-over grazing system
MetadataShow full item record
CitationOnsager, J. A. (2000). Suppression of grasshoppers in the Great Plains through grazing management. Journal of Range Management, 53(6), 592-602.
PublisherSociety for Range Management
JournalJournal of Range Management
AbstractIt was hypothesized that grazing management could mitigate grasshopper outbreaks on native rangeland in the northern Great Plains. Key practices would require deliberate variation in timing and intensity of grazing events, preservation of canopy during critical periods of grasshopper development, and reductions in areas of bare soil. The twice-over rotational grazing system appeared compatible with those requirements. Grasshopper population trends were monitored during 1993–1995 and 1997–1998 on commercial native rangeland under twice-over rotational grazing vs traditional season-long grazing. A ubiquitous pest grasshopper, Melanoplus sanguinipes (Fabricius), occurred at every sample site during each year in numbers sufficient to provide life history parameters for comparison between treatments. Under rotational grazing, the nymphs developed significantly slower and their stage-specific survival rates were significantly lower and less variable. Consequently, significantly fewer adults were produced signifi-cantly later in the season under rotational grazing.Seasonal presence of all grasshopper species combined averaged 3.3X higher under season-long grazing than under rotation-al grazing. Local outbreaks that generated 18 and 27 adult grasshoppers per m2 under season-long grazing in 1997 and 1998, respectively, did not occur under rotational grazing. The outbreaks consumed 91% and 168%, respectively, as much forage as had been allocated for livestock, as opposed to 10% and 23%, respectively, under rotational grazing. Of 9 important grasshopper species, none were significantly more abundant at rotational sites than at season-long sites. Three species that were primary contributors to outbreaks under season-long grazing remained innocuous under rotational grazing. It therefore appears that outbreak suppression through grazing management is feasible in the northern Great Plains.
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Grazing systems, stocking rates, and cattle behavior in southeastern WyomingHepworth, K. W.; Test, P. S.; Hart, R. H.; Waggoner, J. W.; Smith, M. A. (Society for Range Management, 1991-05-01)Grazing systems and stocking rates are used to influence livestock grazing behavior with the intent of improving livestock and vegetation performance. In 1982, a study was initiated to determine effects of continuous, rotationally deferred, and short-duration rotation grazing and moderate and heavy stocking rates on steer gains, range vegetation, and distance traveled by and activity patterns of steers. Steers were observed from dawn to dark on 12 dates during 1983, 1984, and 1985, and activity recorded every 15 minutes. Eight steers per treatment (system X stocking rate combination) per date were observed in 1983 and 1984, and 10 per treatment in 1985. In 1984 and 1985, map locations of all steers were recorded at the same times as activity, and distance traveled summed from distances between successive map locations. In 1984, activity of 3 steers per treatment was electronically monitored during darkness. Steers grazed approximately 8.6 hr per day during daylight and 1.6 hr during darkness. Steers grazed an average of 8.9 hr/day during daylight under moderate vs 8.1 hr under heavy stocking, but stocking rate interacted with date in 1984 and grazing system in 1985. Steers traveled farther under continuous than under short-duration rotation grazing at both stocking rates in 1984, but only at the high stocking rate in 1985. Steers had to travel farther to water in the continuous pastures, and may have had to cover a greater area in an effort to select a more desirable diet, particularly under heavy stocking. These differences were not reflected in differences in gain among stocking rates or grazing systems.
Grazing systems, pasture size, and cattle grazing behavior, distribution and gainsHart, R. H.; Bissio, J.; Samuel, M. J.; Waggoner, J. W. (Society for Range Management, 1993-01-01)Reduced pasture size and distance to water may be responsible for the alleged benefits of intensive time-controlled rotation grazing systems. We compared cattle gains, activity, distance traveled, and forage utilization on a time-controlled rotation system with eight 24-ha pastures, on two 24-ha pastures grazed continuously (season-long), and on a 207-ha pasture grazed continuously, all stocked at the same rate. Utilization on the 207-ha pasture, but not on the 24-ha pastures, declined with distance from water. At distances greater than 3 km from water in the 207-ha pasture, utilization was significantly less than on adjacent 24-ha pastures, at distances of 1.0 to 1.6 km from water. Cows on the 207-ha pasture travelled farther (6.1 km/day) than cows on the 24-ha rotation pastures (4.2 km/day), which traveled farther than cows on the 24-ha continuously grazed pastures (3.2 km/day). Grazing system, range site, slope, and weather had minimal effects on cow activity patterns. Gains of cows and calves were less on the 207-ha pasture (0.24 and 0.77 kg/day, respectively) than on the 24-ha rotation pastures or 24-ha continuously grazed pastures (0.42 and 0.89 kg/da, respectively), with no differences between the latter. Calculated "hoof action" on the rotation pastures was less than that demonstrated to increase seed burial and seedling emergence. Intensive rotation grazing systems are unlikely to benefit animal performance unless they reduce pasture size and distance to water below previous levels, decreasing travel distance and increasing uniformity of grazing.