Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia

Approximately 3.1 Mha (22%) of the agricultural area of south-eastern Australia can be classified as native pasture. There is the assumption that, owing to the widespread occurrence of low-fertility soils in Australia, native grass species do not respond to increased phosphorus (P) fertility. Currently, there are no industry recommendations of target soil-test P values for native-grass-based pastures. This paper reviews the responses of perennial native pasture species endemic to south-eastern Australia to P application in controlled environments, surveys, replicated experiments and paired-paddock trials. Eighty-seven site-years of trial data where different levels of P were applied, conducted over the last two decades, on native-based pastures in south-eastern Australia are reviewed. Data indicate that application of P fertilisers to native grass pastures can increase dry matter (DM) production and maintain pasture stability. However, minimum targets for herbage mass (800 kg DM/ha) and groundcover (80%) are required to ensure persistence of perennial native grasses. Stocking rates also need to match carrying capacity of the pasture. Based on previous research, we recommend target soil-test (Olsen; 0–10 cm) P levels for fertility-tolerant native grass pastures, based on Microlaena stipoides, Rytidosperma caespitosum, R. fulvum, R. richardsonii, R. duttonianum and R. racemosum, of 10–13 mg/kg, whereas for pastures based on fertility-intolerant species such as Themeda triandra, lower levels of <6 mg/kg are required to ensure botanical stability.

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Development of a system to rank perennial ryegrass cultivars according to their economic value to dairy farm businesses in south-eastern Australia

Animal Production Science ◽

10.1071/an17815 ◽

2018 ◽

Vol 58 (8) ◽

pp. 1552 ◽

Cited By ~ 9

Author(s):

C. M. Leddin ◽

J. L. Jacobs ◽

K. F. Smith ◽

K. Giri ◽

B. Malcolm ◽

...

Keyword(s):

Perennial Ryegrass ◽

Mixed Model ◽

Linear Mixed Model ◽

Economic Value ◽

Dairy Farm ◽

Grass Species ◽

South Eastern ◽

Eastern Australia ◽

Forage Value ◽

South Eastern Australia

Dairy production systems in south-eastern Australia are based primarily on grazed pasture. Perennial ryegrass (Lolium perenne L.) is the major grass species used in this region and farmers are faced with the challenge of choosing from more than 60 commercially available cultivars. This paper describes the development of a system termed as a forage value index that ranks the overall performance of perennial ryegrass cultivars relative to cultivar Victorian according to the summation of the estimated difference in the value of seasonal dry-matter (DM) yield of the cultivars. Average predicted seasonal DM yields were calculated by analysing the results of eight available perennial ryegrass plot trials across south-eastern Australia, using a multi-environment, multi-harvest linear mixed model. The differences in the model-predicted DM yield of each cultivar was compared with cultivar Victorian in each of five seasonal periods (autumn, winter, early spring, late spring, summer) to generate a series of performance values (1 per period) for each cultivar. Each performance value was then multiplied by an economic value (AU$/kg extra pasture grown) relating to each of four regions (Gippsland, northern Victoria, south-western Victoria, Tasmania) and seasonal period and aggregated to generate an overall forage value index rating for each cultivar. Economic values ranged from AU$0.11 to AU$0.39 per extra kilogram of DM grown, depending on the season and region, which translated into estimated benefits on dairy farms of up to AU$183 per ha per year for farmers that use high-yielding cultivars in place of cultivar Victorian perennial ryegrass.

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Vegetation Changes after 10 Years of Grazing Exclusion and Intermittent Burning in a Themeda triandra (Poaceae) Grassland Reserve in South-eastern Australia

Australian Journal of Botany ◽

10.1071/bt98011 ◽

1999 ◽

Vol 47 (4) ◽

pp. 537 ◽

Cited By ~ 33

Author(s):

Ian D. Lunt ◽

John W. Morgan

Keyword(s):

Temperate Grassland ◽

Vegetation Changes ◽

Vegetation Composition ◽

Themeda Triandra ◽

Grassland Species ◽

South Eastern ◽

The Past ◽

Eastern Australia ◽

Weedy Species ◽

South Eastern Australia

Changes in the vegetation composition of a remnant Themeda triandra Forsskal grassland in south-eastern Australia were documented following the replacement of stock grazing with intermittent burning at 3–11-year intervals. The vegetation was initially sampled in 1986, 1 year after stock were removed, and then 10 years later in 1996. Most frequently encountered grassland species were abundant in both surveys, although there was little correspondence between species richness at the quadrat scale in 1986 and 1996. Total floristic richness increased slightly over the 10-year period, owing to the proliferation of tall forbs with wind-blown seeds, including exotic thistles and colonising native forbs. Unfortunately, most native ‘increasers’ were ‘weedy’ species which are not typical or common components of species-rich temperate grassland remnants in southern Victoria. Thus, replacing grazing with intermittent burning has not resulted in the flora becoming more similar to that of high-quality, species-rich grassland remnants, but instead, has promoted a group of ruderal colonisers. The ability to identify factors contributing to particular botanical changes was hampered by the design of the management regimes implemented over the past decade. Suggestions are provided to overcome these difficulties, incorporating principles from adaptive management.

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