The Sustainable Grazing Systems Pasture Model: description, philosophy and application to the SGS National Experiment

Johnson, I. R.; Lodge, G. M.; White, R. E.

doi:10.1071/ea02213

Cited by 113 publications

(69 citation statements)

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“…When precipitation changes negatively impacted pasture growth, more stored forage was required and environmental impact tended to increase. Future analyses should move to a more precise spatial scale and utilize more precise pasture simulation models (Graux et al, 2011;Johnson et al, 2003;Moore et al, 1997;Riedo et al, 1998) to accurately simulate heterogeneity to help identify ideal management practices across a varied landscape. An additional area for future research could be modeling the long-term response of pastures to variation in climate and grazing management system.…”

Section: Trends In Precipitation Impacts Across Regionsmentioning

confidence: 99%

Optimizing diet and pasture management to improve sustainability of U.S. beef production

White

Brady

Capper³

et al. 2014

Agricultural Systems

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a b s t r a c tSystem sustainability balances environmental impact, economic viability and social acceptability. Assessment methods to investigate impacts of enterprise management and consumer decisions on sustainability of beef cattle operations are critically needed. Tools of this nature are especially important given the predictions of climate variability and the dependence of beef production systems on forage availability. A model optimizing nutritional and pasture management was created to examine the environmental impact of beef production. The model integrated modules calculating cradle-to-farm gate environmental impact, diet cost, pasture growth and willingness to pay (WTP). Least-cost diet and pasture management options served as a baseline to which environmental-impact reducing scenarios were compared. Economic viability was ensured by a constraint limiting change in diet cost to less than consumer WTP. Increased WTP was associated with improved social acceptability. Model outputs were evaluated by comparing to published data. Sensitivity analysis of the WTP constraint was conducted. A series of scenarios then examined how forecasted changes in precipitation patterns might alter forage supply and opportunities to reduce environmental impact in three regions in the United States. On a national scale, single-objective optimization indicated individual reductions in greenhouse gases (GHG), land use and water use of 3.6%, 5.4% and 4.3% were possible by changing diets. Multi-objective optimization demonstrated that GHG, land and water use could be simultaneously reduced by 2.3%. To achieve this change, cow-calf diets relied on grass hay, continuously-or rotationally-grazed irrigated and fertilized pasture as well as rotationally-grazed pasture. Stocker diets used rotationally-grazed, irrigated and fertilized pasture and feedlot diets used grass hay as a forage source. The model was sensitive to consumer WTP. When alternative precipitation patterns were simulated, opportunities to decrease the environmental impact of beef production in the Pacific Northwest and Texas were reduced by precipitation changes; whereas opportunities in the Midwest improved. Economic viability, rather than biological limitations, reduced the potential to improve environmental impact under future precipitation scenarios. Decreased spring rainfall resulted in lower pasture yields and required greater use of stored forages. Related increases in diet cost reduced opportunities to appropriate funds toward investment in environmental-impact reducing pasture management strategies. The model developed in this study is a robust tool that can be used to assess the impacts of enterprise management and consumer decisions on beef production sustainability.

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Section: Trends In Precipitation Impacts Across Regionsmentioning

confidence: 99%

Optimizing diet and pasture management to improve sustainability of U.S. beef production

White

Brady

Capper³

et al. 2014

Agricultural Systems

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“…The Sustainable Grazing Systems (SGS) pasture model (version 4.8.6) (Johnson et al 2003) was used to simulate the impact of climate change on rainfed (non-irrigated) pasture growth at each of the five sites. The SGS model has been shown to realistically simulate monthly and annual pasture production for sites across southern Australia, under a wide range of soil types and pasture-management options Lodge and Johnson 2008).…”

Section: Systems Simulationsmentioning

confidence: 99%

“…Growth-limiting factors of temperature (GLF temperature ) and water (GLF water ) are used in SGS to identify the extent of limitation to simulated pasture growth. Threshold temperatures for the simulated pasture species were >288C (Mitchell 1956;Waller and Sale 2001) and <28C, above and below which a recovery period for the pasture is required (Johnson et al 2003). The GLFs are on a scale of 0-1, where pasture growth becomes increasingly limited as the GLF decreases towards zero.…”

Section: Systems Simulationsmentioning

confidence: 99%

Beneficial impacts of climate change on pastoral and broadacre agriculture in cool-temperate Tasmania

et al. 2014

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Abstract. Although geographically small, Tasmania has a diverse range of regional climates that are affected by different synoptic influences. Consequently, changes in climate variables and climate-change impacts will likely vary in different regions of the state. This study aims to quantify the regional effects of projected climate change on the productivity of rainfed pastoral and wheat crop systems at five sites across Tasmania. Projected climate data for each site were obtained from the Climate Futures for Tasmania project (CFT). Six General Circulation Models were dynamically downscaled to~10-km grid cells using the CSIRO Conformal Cubic Atmospheric Model under the A2 emissions scenario for the period 1961-2100. Mean daily maximum and minimum temperatures at each site are projected to increase from a baseline period to 2085 (2071-2100) by 2.3-2.78C. Mean annual rainfall is projected to increase slightly at all sites. Impacts on pasture and wheat production were simulated for each site using the projected CFT climate data. Mean annual pasture yields are projected to increase from the baseline to 2085 largely due to an increase in spring pasture growth. However, summer growth of temperate pasture species may become limited by 2085 due to greater soil moisture deficits. Wheat yields are also projected to increase, particularly at sites presently temperature-limited. This study suggests that increased temperatures and elevated atmospheric CO 2 concentrations are likely to increase regional rainfed pasture and wheat production in the absence of any significant changes in rainfall patterns.

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“…The objective of this study was to quantify the net effect of future climate scenarios on pasture production systems, using the biophysical grazing systems models DairyMod and the SGS Pasture Model (Johnson et al 2003. The specific aims were: (1) to predict plant production responses to elevated CO 2 concentrations; (2) to quantify the net effect of 3 future climate scenarios, based on regional projections for changes to rainfall, temperature, solar radiation, relative humidity, and atmospheric CO 2 concentrations in 2030 and 2070, on the production, species composition, and soil water balance of 5 current pasture systems in eastern Australia; and (3) where large reductions in pasture dry matter (DM) production were predicted, to examine if these changes could be mitigated by increasing plant root depth.…”

Section: Introductionmentioning

confidence: 99%

Climate change effects on pasture systems in south-eastern Australia

Johnson²,

et al. 2009

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Abstract. Climate change projections for Australia predict increasing temperatures, changes to rainfall patterns, and elevated atmospheric carbon dioxide (CO 2 ) concentrations. The aims of this study were to predict plant production responses to elevated CO 2 concentrations using the SGS Pasture Model and DairyMod, and then to quantify the effects of climate change scenarios for 2030 and 2070 on predicted pasture growth, species composition, and soil moisture conditions of 5 existing pasture systems in climates ranging from cool temperate to subtropical, relative to a historical baseline. Three future climate scenarios were created for each site by adjusting historical climate data according to temperature and rainfall change projections for 2030, 2070 mid-and 2070 high-emission scenarios, using output from the CSIRO Mark 3 global climate model. In the absence of other climate changes, mean annual pasture production at an elevated CO 2 concentration of 550 ppm was predicted to be 24-29% higher than at 380 ppm CO 2 in temperate (C 3 ) species-dominant pastures in southern Australia, with lower mean responses in a mixed C 3 /C 4 pasture at Barraba in northern New South Wales (17%) and in a C 4 pasture at Mutdapilly in south-eastern Queensland (9%). In the future climate scenarios at the Barraba and Mutdapilly sites in subtropical and subhumid climates, respectively, where climate projections indicated warming of up to 4.48C, with little change in annual rainfall, modelling predicted increased pasture production and a shift towards C 4 species dominance. In Mediterranean, temperate, and cool temperate climates, climate change projections indicated warming of up to 3.38C, with annual rainfall reduced by up to 28%. Under future climate scenarios at Wagga Wagga, NSW, and Ellinbank, Victoria, our study predicted increased winter and early spring pasture growth rates, but this was counteracted by a predicted shorter spring growing season, with annual pasture production higher than the baseline under the 2030 climate scenario, but reduced by up to 19% under the 2070 high scenario. In a cool temperate environment at Elliott, Tasmania, annual production was higher than the baseline in all 3 future climate scenarios, but highest in the 2070 mid scenario. At the Wagga Wagga, Ellinbank, and Elliott sites the effect of rainfall declines on pasture production was moderated by a predicted reduction in drainage below the root zone and, at Ellinbank, the use of deeper rooted plant systems was shown to be an effective adaptation to mitigate some of the effect of lower rainfall.

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The Sustainable Grazing Systems Pasture Model: description, philosophy and application to the SGS National Experiment

Cited by 113 publications

References 0 publications

Optimizing diet and pasture management to improve sustainability of U.S. beef production

Optimizing diet and pasture management to improve sustainability of U.S. beef production

Beneficial impacts of climate change on pastoral and broadacre agriculture in cool-temperate Tasmania

Climate change effects on pasture systems in south-eastern Australia

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