An Australian temperate pastures database

Pearson, Craig J.; Brown, RF; Collins, WJ; Archer, KA; Wood, M. S.; Petersen, Claus Leth; Bootle, B.W.

doi:10.1071/a96095

Cited by 55 publications

(19 citation statements)

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“…Similar low white clover contents of pastures were reported earlier in a survey of Australian temperate pastures (Pearson et al 1997;Hill and Donald 1998), and also earlier in Victoria (Ward and Quigley 1992). It would thus appear that pasture clover contents, and potential N 2 fixation in Australian perennial pastures has probably not improved in almost 20 years, regardless of the increased application of fertiliser N. Farmers appear reluctant to resow legumes (Ward and Quigley 1992).…”

Section: The Achilles Heel: Low White Clover Content Of Pasturessupporting

confidence: 58%

Nitrogen fixation in Australian dairy systems: review and prospect

Unkovich¹

2012

Crop Pasture Sci.

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Abstract. Quantitative measurement of N 2 fixation has rarely been conducted in Australian dairy pastures. The available data indicate that annual N 2 fixation rates in Australian dairy pastures are generally low, due to low pasture legume content. With typical legume contents of grazed pastures less than 30% of total pasture biomass production, annual N 2 fixation in herbage is usually much less than 50 kg ha -1 year -1 . Other factors which are likely to be able to contribute to increased N 2 fixation input (rhizobia, mineral N management, soil acidity, soil water contents) will have little impact until such time as legume contents are increased. In contrast, for some hay systems, such as those using lucerne, N 2 fixation input is shown to be high (200-300 kg ha). While pasture clover contents remain low there is little value in study or measurement of N 2 fixation, nor in complex modelling, as N 2 fixation will be of little quantitative importance. However, where legume contents, and thus potential N 2 fixation are increased, there is scope for investigation into potential increases in N input from this source, which is invariably linked to fertiliser application, the management of grazing and the N returns in urine and dung. These are the major influences on sward N dynamics and legume N 2 fixation. The inoculant rhizobia used for white clover in Australia (TA1) is likely to be suboptimal. Isolated in Tasmania in 1953 it has been shown to be inferior in N 2 fixation compared with other strains on several occasions. Root pests and diseases are likely to be prevalent and impact directly on clover root growth and perhaps nodulation.Modelling is often used to describe the probable influence of management and/or climate on the operation of agricultural systems. Reliable modelling of N 2 fixation requires capacity to integrate the effects of grazing and pasture composition on soil mineral N dynamics, the influence of this mineral N on nodulation and on suppression of N 2 fixation, and environmental and management influences on soil rhizobial populations. Currently no models have demonstrated this capacity. At present, a suitably calibrated regression model is probably a good option for modelling N 2 fixation in Australian dairy pastures.Environmental benefits ensuing from increasing N 2 fixation and substituting this for fertiliser N are likely to be greater offfarm (reduced GHG emissions at site of fertiliser manufacture) than on, if current fertiliser management is optimal. Nevertheless substituting fixed N for fertiliser N would have modest environmental and feed efficiency benefits.

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Section: The Achilles Heel: Low White Clover Content Of Pasturessupporting

confidence: 58%

Nitrogen fixation in Australian dairy systems: review and prospect

Unkovich¹

2012

Crop Pasture Sci.

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“…In each pot, 20 seeds of Medicago sativa L.(legume) and 10 seeds of Phalaris aquatic L.(C3 grass) were sown and thinned to 5 seedlings of each plant at 7 days after sowing (DAS). These species are the two most widely used perennial species for improved pastures in New South Wales, Australia (Pearson et al, 1997). We added a basal nutrient solution at 10 DAS to all pots with the following nutrients (g m À2 ): K (19.3); S (2.95); Mg (2.15); Ca (1.27); Cu (0.006); Mn (0.083); Zn (0.045); B (0.014); Fe (0.09).…”

Section: Experimental Designmentioning

confidence: 99%

Phosphorus addition enhances loss of nitrogen in a phosphorus-poor soil

Dijkstra

2015

Soil Biology and Biochemistry

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“…Climates and soil types vary widely; for example, annual rainfall at the locations modelled in this study varies from 299 to 1091 mm and mean annual temperature from 11.6 to 19.1 C (Table 1). Forage types are consequently very diverse (Pearson et al 1997). Projected climate changes also vary across the study area (Christensen et al 2007).…”

Section: Variation Of the Effects Of Adaptations Across Space Time Amentioning

confidence: 99%

Climate change and broadacre livestock production across southern Australia. 3. Adaptation options via livestock genetic improvement

Moore

Ghahramani

2014

Anim. Prod. Sci.

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Abstract. Climate change is predicted to reduce the productivity of the broadacre livestock industries across southern Australia; to date there has been no formal evaluation of the potential of genetic improvement in cattle or sheep to ameliorate the impacts of changing climates. We used the GRAZPLAN simulation models to assess selection of five traits of sheep and cattle as adaptation options under the SRES A2 global change scenario. Analysis of the breeding strategies was carried out for 25 representative locations, five livestock enterprises and three future years (2030, 2050, 2070). Uncertainty in future climates was taken into account by considering projected climates from four global circulation models. For three sheep enterprises, breeding for greater fleece growth (at constant body size) was predicted to produce the greatest improvements in forage conversion efficiency, and so it was the most effective genetic adaptation option. For beef cow and steer enterprises, breeding for larger body size was most effective; for beef cows, however, this conclusion relied on per-animal costs (including provision of bulls) remaining stable as body size increases. Increased conception rates proved to be less effective but potentially viable as an adaptation in beef cow and crossbred ewe enterprises. In the southern Australian environments that were analysed, our modelling suggests that breeding for tolerance to heat stress is unlikely to improve the performance of livestock production systems even at 2070. Genetic improvement of livestock was able to recover much less of the impact of climate change on profitability at drier locations where the need for adaptation is likely to be greatest. Combinations of feedbase and livestock genetic adaptations are likely to complement one another as the former alter the amount of forage that can be consumed, while the latter affect the efficiency with which consumed forage is converted to animal products. Climate change impacts on pasture production across southern Australia are likely to have only small effects on methane emissions intensity, as are a range of candidate genetic and feedbase adaptations to climate change; methane emissions per hectare in future climates will therefore be driven mainly by changes in livestock numbers due to alterations in pasture productivity.

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An Australian temperate pastures database

Cited by 55 publications

References 0 publications

Nitrogen fixation in Australian dairy systems: review and prospect

Nitrogen fixation in Australian dairy systems: review and prospect

Phosphorus addition enhances loss of nitrogen in a phosphorus-poor soil

Climate change and broadacre livestock production across southern Australia. 3. Adaptation options via livestock genetic improvement

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