2004 Annual Report
Dickinson Research Extension Center
1089 State Avenue
Dickinson, ND 58601
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Implementing Biologically Effective Grazing Management
Llewellyn L. Manske PhD
North Dakota State University
Dickinson Research Extension Center
Management of grasslands for a "use", whether for livestock forage, wildlife habitat, or aesthetics, is management of the use, not management of the grassland resources. The typical grassland management for a use is not sustainable on a long-term basis. Plant-friendly grassland management that meets the biological requirements of the plants and facilitates ecological processes enhances the grassland ecosystem as a natural resource for numerous simultaneous uses. A healthy grassland ecosystem managed by biologically effective practices produces more livestock forage, better wildlife habitat, and inspirational beauty. The same results cannot be achieved through practices based on management-for-a-use concepts.
Three biologically effective management practices that benefit the grassland resources and improve plant health are recommended:
Implementation of biologically effective grazing management strategies that meet the biological requirements of the plants, enhance plant health status, and facilitate the operation of ecological processes is the long-term solution to management-caused herbage reduction problems. The result of these management effects is sustained high performance levels of healthy grassland ecosystems.
The twice-over rotation system is a biologically effective grazing management strategy developed for use in the Northern Plains. It was designed to manipulate processes that result in beneficial changes to plant growth, soil organisms, and biogeochemical cycles in the ecosystem. The twice-over rotation system on native rangeland with complementary domesticated grass spring and fall pastures coordinates defoliation with grass phenological growth stages to enhance vegetation, livestock, and wildlife performance.
The twice-over rotation system begins grazing in May, on a spring pasture of crested wheatgrass or other early growing domesticated cool-season grass that has reached the third-leaf stage, the earliest plant-growth stage at which grasses can be grazed without damage. Native grasses begin seasonal development more slowly, and the use of domesticated grass pastures in May protects native pastures by delaying grazing on them until the plants have reached the third-leaf stage.
A 3- to 6-pasture native range rotation system is used from early June until mid October, with each pasture grazed for two periods. Each native rangeland pasture is grazed for 7 to 17 days during the first period, the 45-day interval from 1 June to 15 July. The number of days each pasture is grazed during the first period is the same percentage of 45 days as the percentage of the total season's grazeable forage each pasture contributes.
During the first period, grasses are between the third-leaf stage and flowering phenophase. Grazing that removes a small amount of leaf area from grasses between these stages of plant development stimulates both tillering from axillary buds and enhanced activity of rhizosphere organisms. Increased vegetative reproduction by tillering contributes to the production of greater herbage weight and nutrient quality, and increased activity of the symbiotic soil organisms supplies the plants with greater quantities of nutrients to support additional grass tiller growth. During the second period, after mid July and before mid October, each pasture is grazed for double the number of days it was grazed during the first period. Increasing the number of secondary tillers improves herbage quality and extends the period of improved livestock performance two to two and a half months, until late September or mid October. The biology of native grass plants does not permit extending these conditions beyond mid October, when native rangeland herbage quality is insufficient to meet the nutritional requirements of lactating cows.
Cows and calves graze a fall pasture of Altai wildrye or other type of wildrye from mid October until weaning in early or mid November. Wildryes are the only perennial grasses that retain nutrient quality in the aboveground portions of the plant later than mid October. Removing livestock from native rangeland pastures at the end of the perennial-plant growing season allows native grasses to conserve stored nutrients that will maintain plant processes over the winter and early spring and to retain the leaf area of secondary tillers and the fall vegetative growth that will become next season's lead tillers. This practice ensures healthy plants in the spring and greater herbage production during the following growing season.
The twice-over rotation system's elevation of plant health and stimulation of beneficial ecosystem processes result in increased plant basal cover and aboveground herbage biomass and improved nutritional quality of forage. The twice-over rotation grazing management system with complementary domesticated grass pastures has a grazing season of more than 6.5 months, with the available herbage above, at, or only slightly below the nutritional requirements for a lactating cow for the entire grazing season.
The increase in quantity and quality of herbage on the twice-over rotation system permits an increase in stocking rate levels; improves individual animal performance; increases total accumulated weight gain, weight gain per acre, and weight gain
per day; reduces acreage required to carry a cow-calf pair for the season; improves net return per cow-calf pair; and improves net return per acre. The increase in basal cover and herbage biomass reduces the number and size of bare soil areas and increases the quantity of residual vegetation. These changes in vegetation produce conditions favorable to the limitation of grasshopper pestiferous species populations. The increase in plant density, herbage production, residual vegetation, and ecosystem health improves the habitat for prairie grouse, ducks, and other waterfowl and ground nesting birds.
Effective management practices meet the biological requirements of the plants and help the ecosystem processes function at their full potential. These management practices improve the performance levels of all grassland ecosystem components, elevate plant health status, and increase productivity of grassland ecosystems. The result is sustained greater herbage weight production, higher quality habitat for wildlife, and stronger livestock weight gain performance.
The benefits of biologically effective grazing practices are both ecological and economic. By implementing the twice-over rotation grazing management strategy, producers protect rangeland health, increase their profits, and help to ensure that the grassland will sustain their cow-calf operation for years to come.
I am grateful to Sheri Schneider for assistance in production of this manuscript. I am grateful to Amy M. Kraus for assistance in preparation of this manuscript.
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