AUSTRALIA
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by
Edwin (Ted) Wolfe  | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1. INTRODUCTION
1.1 Preamble 1.2 Agricultural development 2. SOILS AND TOPOGRAPHY 2.1 Main topographical features 2.2 Soils 3. CLIMATE AND AGRO-ECOLOGICAL ZONES 3.1 Climate 3.2 Agro-ecological zones 4. RUMINANT LIVESTOCK PRODUCTION SYSTEMS 4.1 Australian livestock production 4.2 Dairy cattle 4.3 Sheep 4.4 Beef production 4.5 Other livestock production 5. THE PASTURE RESOURCE 5.1 Native grasslands 5.2 Sown pasture types and species, temperate Australia 5.3 Sown pasture species, subtropical and tropical Australia 6. OPPORTUNITIES FOR IMPROVEMENT OF PASTURE RESOURCES 6.1 Research outcomes 6.2. Pasture management for productivity and sustainability 6.3 Future opportunities 7. RESEARCH AND DEVELOPMENT ORGANIZATIONS AND PERSONNEL 7.1 The current landscape 7.2 List of selected personnel/organizations involved in pasture R & D 8. REFERENCES 9. CONTACTS AND ACKNOWLEDGEMENTS | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1. INTRODUCTION
1.1 Preamble Australia is in the Southern Hemisphere between the Indian and South Pacific oceans (Figures 1a and 1b). The country comprises continental Australia and a southern island State (Tasmania), which together extend from longitudes 113o09’E to 153o38’E and latitudes 12o00’S to 43o40’S, and numerous small islands. The maximum north-south and east-west distances are about 3600 km and 3900 km respectively.
Below, a brief history of the agricultural development of Australia is outlined. Then follow sections on the soil resources and climate, the broad agro-ecological zones and the distribution of sheep and cattle across these zones. The following sections on production systems, pasture/fodder resources and future research/development opportunities are considered from a contemporary perspective, drawing selectively on the rich history of the Australian grazing industries and taking into account the likely future trends in climate, global resources, the demand for livestock products and industry policy shifts. 1.2 Agricultural development Aboriginal tribes occupied the continent and nearby islands for about 60,000 years prior to the arrival of the first white immigrants/settlers from England in 1788 and afterward. The Aboriginal people were distinctive hunter-gatherers who possessed a deep sense of kinship with the lands, animals and geographical features of the continent. By the late 18th century, the Aboriginal population numbered around 300,000 who collectively spoke about 250 native languages. They harvested native animals, insects and plant foods, utilising fire for cooking, warmth and land management. A short history of post-settlement agricultural development in Australia was given by Wolfe and Dear (2001). Early in the 19th century, British immigrants explored and occupied rural Australia, partially displacing the Aboriginal people and disrupting the population of grass-eating macropods (kangaroos) with sheep and cattle, which grazed and multiplied on the vast areas of native grasslands. Early development fanned out to occupy a moist crescent around the semi-arid and arid interior of Australia, from the SE sections of South Australia (SA) (300–650 mm median annual rainfall), temperate Victoria (300–900 mm), the central plains, slopes and tablelands of New South Wales (NSW) (350–900 mm), up and down the wetter coast of NSW (900 –1200 mm), and from sub-tropical SE Queensland to the central and eastern tropical areas of Queensland (500 to 1800 mm median annual rainfall). From the 1840s, the SW corner of Western Australia (WA) (300–650 mm median annual rainfall) was developed. The original native grasslands comprised tall warm-season perennial grasses (e.g. Themeda triandra, Poa labillarderi, Austrostipa aristiglumis and Heteropogon contortus) which, depending on rainfall and grazing intensity, gave way towards shorter native species such as redgrass (Bothriochloa macra), bluegrass (Dichanthium sericeum), the wallaby grasses (Austrodanthonia spp.) and windmill grass (Chloris truncata) (Moore, 1970). In southern Australia, a range of species from around the Mediterranean were introduced accidentally and became naturalised; these included several cool-season annual grasses (Bromus, Hordeum, Vulpia spp.), forbs (Arctotheca calendula, Echium plantagineum) and annual legumes (Trifolium spp., Medicago spp.). During the first century of exploration and exploitation (Shaw, 1990), the expanding flocks of grazing livestock (Table 1) were sustained by way of a combination of activities, such as clearing trees and shrubs, the regular burning of the open woodland-grassland and scrub-grassland communities, the granting of grazing rights and eventual land tenure, fencing/yards and the provision of reliable water supplies, better techniques of animal breeding and husbandry, investment and banking services that followed the discovery of gold in the 1850s, and the building of the Australian railway system from 1855. By 1891, when most of the railway system was in place, more sheep were grazing the Australian landscape than occur today (Table 1); however, the numbers of sheep and cattle were reduced during the next decade by a general economic depression and by the ‘Federation drought’, which began in the mid 1890s and reached its devastating climax in late 1901 and 1902. Scientific agriculture began late in the 19th century with the establishment of experimental farms, which during the early 20th century helped to promote a consolidation phase comprising new techniques of dry farming, purposeful wheat breeding, superphosphate fertilizer and mechanisation (Barr and Cary, 1992). To counteract the depletion of soil organic matter, a technique of ley farming with annual pasture legumes was developed for slightly acidic soils in Victoria (with subterranean clover, Trifolium subterraneum) and alkaline soils in SA (with annual medics, Medicago spp.). However, because of the depression and then war, there was little change in on-farm practices and outputs between 1930 and 1950, and land degradation (erosion of croplands, overgrazing of pasture lands with livestock and rabbits) continued. A highlight during the 1940s was the discovery of several trace element deficiencies (copper, molybdenum, zinc and cobalt) that affected the growth and nitrogen fixation of legumes on large tracts of soils in coastal SA and WA (copper, zinc and cobalt) and in south-eastern Australia (molybdenum) (Williams and Andrew, 1970). There was a rapid expansion in improved pastures from 1950 (5 000 000 ha of improved pastures) until 1975 (>20 million ha), based on prior investments in agricultural research, a wool boom in the early 1950s, incentives for investment in agriculture (taxation concessions, a superphosphate bounty) and the advent of aerial agriculture. However, once again, this expansion was accompanied by problems that were evident during the 1970s and 1980s, including a widespread decline in the productivity of pasture legumes due in part to the occurrence of new plant diseases, insect pests and weeds; a worsening cost-price squeeze; and land degradation phenomena such as eucalyptus tree dieback, soil acidification and salinisation. The collective marketing scheme for wool collapsed and a steep decline in sheep numbers began from 1975. Table 1. Agricultural development in Australia, 1820-2005*
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| 2. TOPOGRAPHY AND SOILS
2.1 Main topographical features Australia, located on the Indo-Australian plate, is the most stable of continents in that it has been least affected by seismic (earthquake), orogenic (mountain-building) and volcanic forces during the past 400 million years. It is also the flattest continent, with an average elevation of 330 m and less than 1% of the total area over 1000 m (Figure 3).
2.2.1 History of soil formation and degradation The underlying geology of Australia was determined 400-100 million years ago. McKenzie et al. (2004) briefly summarised the main implications of climate change for Australian soils over the Cretaceous-Tertiary Periods (100 million years before present), Quaternary Period (2.5 million years) and the most recent 150,000 years. Parts of the Australian continent are extremely old, with the oldest land surface in the world being found in the Pilbara region of WA. Unlike other continents, the scale of soil-enriching events such as mountain uplifts, glaciations and volcanic activity have been low. Low relief, tectonic stability and aridity are factors that account for the deeply weathered regolith, as well as the sandiness and the low fertility of most Australian soils. Furthermore, Australian groundwater resources are relatively high in salt, compared with continents such as North America and Europe, a consequence of periods of inundation of the Australian continent by the sea and a low rate of recharge with rainfall or fresh groundwater. Natural cycles of erosion (water, wind) and deposition (water, wind, lava flows) have further shaped Australian landscapes. However, the human population has had the most impact. The use of fire by the Aboriginal people decreased the vegetation cover and marginally increased the loss of soil nutrients and rate of soil erosion. With the arrival of British convicts, colonists and immigrants from 1788, “the severity of soil degradation, particularly in the 100 years after 1850, was extreme” (McKenzie et al., 2004). Activities and their negative impacts on Australian soils included clearing the deep-rooted native vegetation (loss of cover, changes in hydrology, loss of nutrient cycling, erosion, salinisation), mining (landscape disruption, nil or inadequate repair, sediment damage and pollution of waterways), overgrazing by livestock and rabbits (vegetation cover and type, soil erosion, surface sealing, nutrient removal), excessive cultivation (oxidation of organic matter, soil erosion, surface sealing and compaction, increased wind and water erosion, nutrient losses), machinery and vehicular traffic (loss of cover, compaction), excavation and construction activities on sensitive soils (e.g. acid sulphate soils) and contamination of soil and groundwater systems with fertilizers and chemicals. During the last half-century, the promotion of sustainable production by research organizations, industry bodies and farmers has lowered the rate of soil degradation through understanding the degradation processes and the implementing more sustainable farming systems and practices. These practices include a reduction in sheep numbers, the control of rabbits, the use of fertilizers and legumes to enhance soil fertility, the adoption of reduced tillage, liming to counteract soil acidity, gypsum treatment for sodic soils, the increased use of perennial plants for reducing groundwater accessions and caps to the allocation of water resources. In urban environments, too, there is a renewed focus on land use, subdivision and site development/management policies, stormwater management and waste disposal systems. The implementation of improved processes for agricultural and urban environments is an ongoing process, now stimulated by the phenomena of climate change, greenhouse gas management, dwindling oil reserves and the supply/demand situation for food.
Isbell (1992) outlined the history of soil classification in Australia. Until the 1970s, the Great Soil Group classification (e.g. podzols, red-brown earths, black earths) was the general system used for describing soils in land surveys and for educating agricultural scientists. For an Atlas of Australian Soils project (1960-68), a factual key developed by K.H. Northcote was used, a key that classified soils into 4 divisions (organic O, uniform U, gradational G and duplex D) according to their organic matter content and texture change down the profile; subdivisions were based on features such as texture (U profiles), limestone content (G profiles) and colour of the B horizon (D profiles). However, neither of these classifications incorporated the vast amount of soils knowledge acquired after the 1960s, particularly in northern Australia. Consequently, an Australian Soils Classification system was developed, published and adopted from the 1990s. This system comprises 14 soil orders (Figure 4). The soils that occur in the main agricultural zones are:
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| 3. CLIMATE AND AGRO-ECOLOGICAL ZONES
3.1 Climate The main drivers of the Australian climate are the circulation patterns of atmosphere and oceans that occur in the Southern Hemisphere. Warm air from the equatorial regions rises, depositing rain, and then is deflected southward by the earth’s rotation. This air descends over the subtropics (Tropic of Capricorn) to form a subtropical ridge of warm, stable, dry air across Australia (Hadley cells). This subtropical ridge of high air pressure across the middle of Australia is responsible for the aridity of the central part of the continent. The ridge moves southward during the Australian summer (drawing moist air into northern Australia) and northward in the Australian winter (allowing low pressure systems in the southern oceans to influence southern Australia), thereby producing seasons of Australian rainfall (Figure 5). High levels of insolation (the amount of solar radiation reaching the surface) occur when the high pressure belts track across the continent, heating the ground surface, raising rates of evaporation and limiting plant growth. Australia is a hot continent (Figure 6). Another important air circulation system – the Walker circulation – links warmer and cooler areas of the oceans in equatorial regions, producing moist south-easterly winds over eastern Australia when there is a large pool of warm water adjacent to eastern Australia, as occurs during a La Niña (wet) phase. These winds are drier and less frequent during the El Niño (dry) phase, a phase that is associated with warm water in the central Pacific Ocean and droughts in eastern Australia. Hence, there is interest in monitoring the ENSO (El Niño – Southern Oscillation) phenomenon, which is rather crudely estimated in Australia by differences in air pressure recorded at Darwin and Tahiti (Southern Oscillation Index). The Indian Ocean Dipole, which is based on a comparison of sea surface temperatures near the equator in both the western and eastern Indian Ocean, is another phenomenon that is associated with wet and dry phases on the Australian continent.
The climate records of the past 100 years identify a general global warming. Parts of Australia seem to be following this trend, which appears to have accelerated in recent years. Temperatures in eastern Australia rose by about 0.5 degrees Celsius over the period 1930 to 1988 (Bureau of Meteorology, 1995) and, across Australia, the mean temperature during 2005 was 1.1 0C higher than the mean for the 1961-90 period. The implications of climate change for pastures and livestock are dealt with in sections 4-6.
The interaction between seasonal rainfall (Figure 5) and seasonal temperatures (Figure 6) delineate the main agro-ecological zones (Figure 7) of semi-arid, temperate and tropical Australia, as well as the adaptation of the main pasture species and livestock types in each zone. Agriculture is fragmentary in the wet/dry north-western and north-eastern tropics (remote from markets, lack of infrastructure, land allocation to the Aboriginal people and mining interests), the semi-arid and arid interior (too dry) and the wet temperate highlands (alpine areas, forests); each of the remaining zones is agriculturally important. Pasture adaptation/production in the temperate and tropical zones follows a similar seasonal regime to crops. In southern Australia, self-regenerating annual pastures, dryland temperate crops (wheat, barley, oats, canola, lupins, peas and chickpea) and forages (cereals for grazing and grain) are grown from May (late autumn) to November late spring); there are also significant areas of perennials including native grasses, sown temperate grasses and dryland lucerne (= alfalfa, Medicago sativa) (Section 5). Further north in the subhumid and wet zones of northern NSW and south-central Queensland, subtropical/tropical perennial grasses and legumes, dryland tropical crops (sorghum, sunflowers) and forages/green manures (forage sorghum, lablab, butterfly pea) are grown from October to April (summer); in inland southern Queensland, lucerne, annual medics and forage oats are grown and grazed in winter when sufficient soil moisture is available. Along the eastern Queensland coast, many native grasslands have been improved by the introduction of sown subtropical and tropical species. The wet/dry monsoonal tropics, where sown pastures are infrequent (Figure 8), remain dominated by native tropical grasses (Section 5) but buffel grass (Cenchrus ciliaris) is sown and has become naturalised over large areas. Of the legumes available for north of the Tropic, a range of stylos (e.g. shrubby stylo S. scabra) have a similar potential. In southern NSW and northern Victoria, on either side of the Murray River which receives water from annual snowmelt stored in high-country water storages, summer crops (rice, maize, soybean), winter crops and forage crops are grown under irrigation, as well as subtropical grass + temperate legume pastures for dairy and fat lamb production (Figure 8). On the subhumid subtropical plains on northern NSW and southern Queensland, limited irrigation water is used for the flood irrigation of areas of cotton production with some soybeans and maize, not pastures. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 4. RUMINANT LIVESTOCK PRODUCTION SYSTEMS 4.1 Australian livestock production An historical overview of Australian agriculture, with chapters devoted to ‘beef and dairy products’ and ‘sheep and wool’, can be found in Henzell (2007). As stated earlier, winter temperatures in 99% of Australia are relatively mild, enabling livestock to graze year-round on native pastures, improved pastures, forages and crop stubbles/residues. Dairy cattle occur mainly in coastal and irrigated areas. European breeds of cattle (Bos taurus) are pastured in southern Australia up to the Tropic (Figure 7). Bos indicus cattle such as the Brahman breed and its crosses are better adapted in several ways (thermoregulation, pest tolerance) to the more tropical environments of northern Australia, and these crosses are also popular in herds below the Tropic. Sheep are pastured from the southern tip of Tasmania up to latitude 20oS in northern Australia, avoiding the humid, wet tropical coast of Queensland. In temperate Australia, year-round stocking rates of about 0.5-2 dry sheep equivalents (dse) per hectare (or the equivalent in cattle) are carried on non-degraded native pastures, with about 8-10 dse on good quality improved pastures. In northern Australia, one beef animal or its equivalent in sheep (8 dse) can be carried per ha on well-improved pastures or on 3 ha of the best native pastures, compared with more than 50 hectares being needed to carry the same animal on the least productive pastures. Domestically, Australians annually consume 37 kg beef and veal (steady trend), 13 kg of sheep meat per capita (steady), along with 25 kg pig meat (↑) and 38 kg poultry (↑) (Australian Bureau of Statistics). Livestock production is geared both to this domestic demand and to export markets for livestock products and livestock.
4.2 Dairy cattle The Australian dairy industry [Photo 1.] has undergone substantial restructuring over the past few years. This process has contributed to the continuing long-term decline in Australian dairy farm numbers, from 118,000 farms in 1960 to 15,600 in 1990 and less than 10,000 today. Victoria is Australia’s largest milk producing state, accounting for more than 60% of the national milk production and more than 70% of manufacturing milk production. The average herd size in Victoria has increased from 150 head in the late 1970s to around 250+ head.
Over the last three decades there has been a halving of sheep numbers (Table 1), to 77 million in 2007/08. This decline was due to the unstable marketing and reduced value of wool, and Australian producers responded by severely reducing their numbers of Merino sheep, the medium-fine wool breed. Over the same period, the numbers of crossbred sheep and other meat-producing breeds were stable and receipts from lamb increased. Currently (2007/08), the sheep industry [Photo 2.] is still an important part of Australia’s economy, with production of 510 kt wool, 435 kt lamb and 259 kt mutton, worth $4,777 m ($2,612 m wool, $1,466 m lamb) – about 11% of the gross value of Australia’s agricultural production. In 2007/08, Australia exported 45% of total lamb production, 77% of total mutton production and 4.09 million live sheep, earning about 2% of Australia’s total export earnings.
4.4 Beef production Australian beef producers [see Photo 3.] supply two main market areas; the domestic market and the export markets. Production of beef and veal was 2,155 kt in 2007/08. The domestic market consists of clients such as retail butchers, supermarkets, hotels, restaurants and institutions. The per capita amount of beef consumed by the Australian public (37-38 kg, see above) is now relatively stable. The proportion of production available for export peaked in the 1990s (60%) but this market now comprises 43% to Japan (364 kt in 2007/08), US (238 kt), Republic of Korea (146 kt) and other markets. Feedlot production, mainly to ‘finish’ cattle, accounted for about 40% of the adult cattle slaughtered annually in Australia. The Australian live cattle export trade, 713,000 head in 2007/08, is the largest in the world.
The distribution of broadacre beef cattle farms in Australia is given in Table 3. In northern Australia, many of the farms (stations) also run sheep. In southern Australia, most of the farms also run sheep and many produce crops as well. Up to 400 head or so, the cattle can be managed by one farm family without additional permanent labour. Table 3. The distribution of broadacre beef cattle farms by numbers of cattle (average between 2001/02 and 2007/08) (Mackinnon, 2009)
In retail butcheries and restaurants in major Australian cities and towns, it is possible to purchase a wide range of meat types, including goat, deer, horse, camel, buffalo, kangaroo and crocodile. Information on the organization of these industries and new animal products is available at www.rirdc.gov.au. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 5. THE PASTURE RESOURCE 5.1 Native grasslands Native grasslands are still a significant component of the pasture resource in all Australian agro-ecological zones, even though large areas have been replaced or modified with improved grasses and legumes (exotic species) that were either deliberately or accidentally imported from world temperate and tropical regions. In southern Australia, these modified areas include the higher rainfall areas (coast, tablelands and slopes), where introduced species contribute most to grassland productivity, and the slopes and plains of the wheat-sheep belt, where crops and pasture legumes predominate. In northern Australia, the development and use of introduced species for pastures has occurred mainly in the last half-century, and there is an overall greater reliance on native grasses. Native grasslands, modified by the agencies of grazing, clearing and fire, are the mainstay of the semi-arid grazing areas. 5.1.1 Native grasslands in southern Australia For the slopes and tablelands of NSW, Moore (1970) described the main botanical changes in pastures in typical Eucalyptus woodland–grassland communities during the first 150 years of clearing and grazing with livestock and rabbits, which accompanied the first white settlers. The original vegetation, dominated by tall warm season perennial tussock grasses such as kangaroo grass (Themeda triandra = T. australis), plains grass (Austrostipa aristiglumis) and poa tussock (Poa labillarderi), was presumably well-adjusted to the ebb and flow of the native herbivores (kangaroos, wallabies, bird life) and occasional fires. Once sheep and cattle were introduced to the tablelands and slopes in the 1830-40s, accompanied by tree-clearing operations, there began a sequential progression (Figure 11) in the botanical composition of the grasslands, toward communities that contained an array of grazing-tolerant, cool- and warm-season native grasses, together with various naturalised annual grasses and forbs that had been introduced into Australia in agricultural seeds and feeds. The main agent of change was presumably continuous defoliation by harder-hoofed animals, with the loss of grazing-susceptible plant species (an early casualty was kangaroo grass) opening the sward to native and exotic invading species. Nutrient redistribution and changes in the seasonal extraction and replenishment of soil water are other processes that presumably influenced these earlier changes in Australian grassland communities (Johnston, 1996). Garden and Bolger (2001) and Wolfe and Dear (2001) used the state and transition model to update the nature and timing of changes that occurred in grasslands on the tablelands of NSW since 1950 (Figure 11). These changes were rapid, driven by the popular practice of aerially applying legumes and superphosphate (originally 100-125 kg/ha/year) to native pastures to provide higher quality feed and to provide nitrogen for grasses, as well as sowing exotic grasses and legumes into herbicide-treated or prepared seedbeds. Other agents of change were grazing at higher stocking rates (which enhanced the transfer of fixed nitrogen to the associated species), invasion by nitrophilous weeds, a process of soil acidification (due to changes in the cycling and distribution of nitrogen and carbon in the grazed ecosystem), various good and bad management practices, bursts of enthusiasm and apathy towards pasture improvement, and wet/dry years. As a consequence, pastures along the NSW slopes and tablelands exist in an array of states (Figure 11), some even reverting back to native species after a history of fertilization and legumes. Several native grasses, especially perennials like the wallaby grasses (Austrodanthonia spp.) and redgrass (Bothriochloa macra), [see Photo 4.] are currently regarded as useful because of their tolerance of grazing, their adaptation and their lack of spiny awns. Poa tussock and weeping grass (Microlaena stipoides) are persistent on wetter, more fertile sites. The main impediments to resowing larger areas of native pastures are their relatively low productivity in favoured areas compared with exotics and the lack of seed, or its high cost if available.
Accurate statistics on current pasture areas in Australia are difficult to obtain due to the nature of the questions asked in the official census that is taken every 5 years. Dear and Ewing (2008), who extracted the area data from the Australian Temperate Pastures database (Hill and Donald, 1998), reported an area (excluding Queensland, NT and tropical WA) of 32 M ha of unimproved native pastures and 6 M ha of improved native pastures (fertilized or fertilized + oversown, mainly in areas with >550 mm average annual rainfall). These values compare with an area of up to 25 M ha of sown pastures in southern Australia. The adaptation of sown species and cultivars in southern Australia is discussed in section 5.2. 5.1.2 Native grasslands in northern Australia General maps of the vegetation and grassland areas of tropical Australia are available in Moore (1970); a more detailed map of the native pasture communities in Queensland was published in Walker and Weston (1990). Along the tropical eastern coast of Queensland and into the nearby ranges and plateaus, where much of the original rainforest has been cleared, there are extensive areas of grassland, dominated by bunch speargrass (Heteropogon contortus) in the drier areas and blady grass (Imperata cylindrica) in the more humid areas, both interspersed with kangaroo grass and forest bluegrass (Bothriochloa bladhii). In the seasonal wet/dry tropics, taller grasses occur, such as perennial and annual Sorghum species, wild rice (Oryza rufipogon, Northern Territory), fire grass (Schizachrium spp., Cape York Peninsula) and ribbon grass (Chrysopogon spp.). Further inland from the coast, the central sub-humid zone in Queensland is dominated by woodlands and acacia scrublands, with smaller areas of grasslands dominated by bluegrasses (Dichanthium spp., Bothriochloa spp.), plains grass and satintop (Bothriochloa erianthoides). The woodland areas, comprising gums (Eucalyptus spp. and Corymbia spp.), sheoak (Casuarina spp.) and cypress pine (Callitris spp.), produced a grassy Aristida-Bothriochloa understorey once they were cleared for grazing, and the dominance of these grasses was maintained by periodic burning. The sub-humid acacia shrublands, comprising brigalow (A. harpophylla) and/or gidgee (A. cambagei), were cleared primarily for cropping but these shrublands also support good quality native and improved pastures. Further inland towards the semi-arid zone, there are large areas of native perennial grasslands such as those dominated by Mitchell grass (Astrebla spp.) that are prized for cattle grazing, along with areas of mulga grasslands (dense to scattered Acacia aneura trees with an understorey of Aristida and Enneapogon annual grasses), spinifex (Triodia irritans) and bluebush grasslands (Kochia spp., Bassia spp., annual and perennial grasses). Sheep are grazed with beef cattle in the sub-humid and semi-arid areas of Queensland but not in the humid eastern tropics (Queensland) or the northern tropics (Queensland, Northern Territory, Kimberley region of WA), where the climate (wet hot summers, dry winters) and tall tropical grasses are suitable only for beef cattle, especially the adapted Bos indicus breeds. In 1996 and 1997, Bortolussi et al. (2005a, 2005b, 2005c) comprehensively surveyed 375 producers representing the northern Australian beef industry that is based on these subtropical and tropical native grasslands. In contrast to southern Australia, where cropping and livestock grazing for meat and wool is conducted on properties that are of moderate size (median 2000 ha) with most beef farms having less than 400 head (Table 3), the median size of the survey properties was 1,669 ha (Maranoa and south-west) to 36,310 ha (north-west) in Queensland (range 324-2,133,100 ha), 304,200 ha in the Northern Territory (range 20,000-1,630,433 ha) and 286,216 in northern WA (range 300-914,386 ha). Median herd sizes were from 1,550 head (central coastal Queensland) to 62,000 (Northern Territory). From the survey, the most commonly used native pasture communities (Table 4) were speargrass (high rainfall, near to the coast) and Mitchell grass (inland plains), while improved pastures based on grasses or grasses + legumes were sown mainly in intermediate areas formerly dominated by black speargrass, woodland (Aristida-Bothriochloa association) or acacia scrub (brigalow, gidgee). Table 4. The frequency of native and sown pasture communities and the average annual liveweight gains of cattle (LWG, kg/head) on 375 surveyed beef properties in northern Australia, 1996/97 (Bortolussi et al., 2005b)
5.1.3 Native or exotic? There is a continuing dialogue in Australia between environmentalists and agricultural scientists, groups that are often opposed on matters such as native grasslands, forest policies and water utilisation/conservation. Australia has replaced huge areas of woodlands and grasslands with crops and with grasslands based on exotic species. The inclusion of superphosphate and exotic pasture species (utilising locally produced seed of adapted or bred cultivars) into farming systems has lifted productivity in a country where soil fertility is limited by weathered soils and by a paucity of useful local legumes. Leaving aside for the moment the difficulty of producing abundant supplies of cheap seed from native species, there is a strong case on sustainability grounds for the use of management options that utilise adapted native grasses, and for the inclusion of a wider range of perennial grasses, particularly C4 species, for pastoral use (Johnston et al., 1999). Johnston et al. (1999) questioned the amount of research and development effort that has gone into replacing indigenous grasses with exotic introductions, many of which fail to persist over the frequent droughts that characterise the Australian climate. They reviewed the evidence for the persistence, productivity and nutritive value of several species of native grasses in grazed pastures, and argued for strategies that utilise adapted, palatable grasses such as wallaby grass in low-input situations and C4 perennials in areas that are prone to hydrologic imbalance. Importantly, however, Johnston et al. (1999) acknowledged the folly of a “one-or-the-other” philosophy, compared with an approach that achieves a complementary fit between a low-input, conservative approach to pasture management and the high-input, exotic species approach to pasture improvement. The high-input approach, at least where sown pastures have been properly managed, has produced notable gains in the productivity of Australian grasslands for wool and red meat production (Smith 2000). The low-input approach is important in lands where restoration is a priority (e.g. on degraded or eroded sites, in national parks or in reference conservancy areas) or where disturbance is unwise. In several States, there are native grassland reference areas that are protected; these areas cannot be modified by oversowing with exotic species, fertilized or cultivated. 5.2 Sown pasture types and species, temperate Australia 5.2.1 Map of zones Figure 12 depicts a general map of the main tropical and temperate pasture zones in Australia. This map updates the zones in Map 5 of Moore (1970), taking into account the adaptation zones for temperate species mapped by Moore and by Hill (1996), the map of Australian agro-ecological zones (Figure 7) and the actual distribution of sown pasture species (Figure 8). 5.2.2 Temperate pasture zones The temperate zones are based on the limits to the adaptation of important pasture species, especially the inland limit that is set by moisture, the arid boundary (Donald, 1970) (Figure 13). The arid boundary for each zone is defined mainly by the P/E ratio (Hill, 1996), where P = precipitation and E = potential evaporation (Figure 2). The main pasture zones are:
Both perennial ryegrass and white clover are well-adapted to defoliation by livestock and both compete well for available resources such as nutrients and light. However, the relatively dry environments and lighter textured soils of Australia confine these species to a favourable fringe along the coast and tablelands of south-eastern Australia, with smaller areas of irrigated pastures occurring inland. The coastal fringe contains the major population centres of Brisbane, Sydney, Melbourne and Hobart. Perennial ryegrass/white clover pastures along with Kikuyu (Pennisetum clandestinum) pastures (see section 5.3) have underpinned much of the Australian dairy industry. The link of these species to dairying remains strong but now the system of milk production is more decentralised towards areas that are closer to fodder and water resources due to the encroachment of the urban fringe on agricultural lands, the scarcity of water and better transport services. Attempts to improve the productivity and reliability of the perennial ryegrass/white clover pasture type, either by breeding/selecting for persistence in ryegrass (Blumenthal et al., 1996, Oram and Lodge, 2003) and white clover (Lane et al., 2000; Jahufer et al., 2002) or by using alternative species such as cocksfoot or tall fescue (Nie et al., 2008), have met with limited success. Tall fescue (cv. Demeter) is useful alone or in combination with other grasses where summer growth is required for production or bloat avoidance, while a number of summer-dormant cultivars offer better persistence where summer rainfall is unreliable. Similarly, both phalaris and cocksfoot possess some desirable agronomic attributes but there are negative aspects of their nutritive value compared with ryegrass (Oram and Lodge, 2003). Phalaris, grown on 4.5 M ha, is second to perennial ryegrass in total pasture sowings and is the dominant temperate sown grass where perennial ryegrass will not persist. It characterises important sheep and cattle meat-producing areas in NSW, Victoria, SA and Tasmania. A deep-rooted, prostrate habit, dense tillering, partial summer dormancy and the presence of a large underground rhizome are features associated with the outstanding persistence of the ‘Australian Commercial’ cultivar. This cultivar possesses important deficiencies such as poor seed production due to shattering, slow seedling establishment, a susceptibility to acidic soils and several anti-nutritional components, factors that have been addressed, at least in part, by breeding (Oram and Lodge, 2003; Oram et al., 2009). However, the presence of phalaris in grazed pastures is generally prized, conferring both stable productivity and sustainability (soil protection, competitive ability with weeds, reduction in groundwater accessions). Lucerne, sown either alone or in mixture with other species, is currently grown on more than 3.5 M ha (Dear and Ewing, 2008), with most of this area occurring in the wheat belt. During the 1980s, after the dominant Hunter River cultivar succumbed to the spotted alfalfa aphid and the blue-green aphid, successful breeding programs were developed to produce several aphid-resistant, Australian-adapted lucerne cultivars with boosted winter activity (Williams, 1998; Humphries and Auricht, 2001). A beneficial spin-off from this effort was the improved tolerance of Australian cultivars to diseases such as phytophthora root rot (Phytophthora medicaginis) and colletotrichum crown rot (Colletotrichum trifolii) (Irwin et al., 2001). These diseases limited lucerne survival in humid summer environments found in northern NSW and Queensland, the zone where lucerne is most needed to restore soil fertility. During the 1990s and into the new millennium, a continuing investment in lucerne improvement was justified, at least in part, by the stronger focus on soil health and agricultural sustainability in the main pasturelands and croplands (Cocks, 2001). Several Australian studies (Turner and Asseng, 2005) have confirmed the value of lucerne in utilising water spared by annual crops and annual pastures, thereby reducing the potential of groundwater recharge both directly (water extraction) and indirectly (creating extra water storage capacity prior to winter). Dear and Ewing (2008) outlined the rationale for a targeted effort to increase the available deep-rooted perennial pasture species for the control of dryland salinity in Australia. Hughes et al. (2008) described the systematic process, including the development of a database of priority species (nearly 700); their screening for weed risk; securing the needed germplasm from Australian and overseas collections or by direct collecting; quarantine; nursery and plot evaluation; and species characterisation and multiplication. A preliminary review of the results of this program was given by Dear et al. (2008) who, among other species, mentioned cullen or tall verbine (Cullen australasicum, an Australian native, leguminous shrub), lotononis (Lotononis bainseii, already available from prior work done in subtropical Australia), several available temperate and tropical perennial grasses and, for discharge (salty) environments, certain legumes (e.g. Melilotus siculus, M. sulcatus) and grasses (e.g. Puccinellia ciliata). This program, restricted somewhat by inadequate funding, is an example of what can be done when experienced, committed professionals work towards a clear objective. Finally in this section, mention needs to be made of the potential of subtropical and tropical perennial C4 species such as Kikuyu, Rhodes grass (Chloris gayana), buffel grass and lotononis in temperate areas, especially in the temperate/subtropical transition zone along the NSW-Queensland coast (Figure 8), the border slopes/plains (Boschma et al., 2009) and for specific purposes such as the management of groundwater accessions in southern Australia (Nie et al., 2008). 5.2.4 New temperate annual legumes for pastures Annual pasture legume options were once largely confined to cultivars of subterranean clover and annual medics. The life cycle and dynamics of these species were outlined by Wolfe and Dear (2001). Subterranean clover, in particular, is well adapted to continuous grazing with livestock. During summer, the pool of hard (impermeable) seed is partially protected from grazing by burr (pod) burial. After germination, the emerging seedlings are unattractive to livestock. In winter, when grazing pressure is high, the continued close grazing of the prostrate herbage stimulates seed production and burr burial in spring. During spring, low grazing pressure (growth exceeds consumption) and burr burial protect the developing inflorescences. Compared with subterranean clover, annual medics are more susceptible to grazing but they produce an abundance of flowers and the seed pods are better adapted to drought. During the 1980s, the release of cultivars of yellow serradella (Ornithopus compressus, tolerant of acidic, sandy soils), Medicago murex (tolerant of acid soils) and balansa clover (Trifolium michelianum, suitable for waterlogged, heavy–textured soils) extended annual legumes into specific niches. From 1990, the changing nature of farming systems and a recognised lack of legume biodiversity triggered a new emphasis on annual pasture legume breeding and selection (Loi et al., 2005). A national effort (Nichols et al., 2007) was directed towards producing annual legumes to deal with particular problems and opportunities, such as legume adaptation on difficult soils (acid, waterlogged or saline), weed and insect threats, longer pasture and cropping phases, deeper-rooted plants to reduce groundwater accessions, and the need for easily harvested and sown seed. As a result, a wide range of species and cultivars are now available for the wheat belt in WA and other States (Table 5). Cultivars of pink or French serradella (Ornithopus sativus), gland clover (Trifolium glanduliferum) and biserrula (Biserrula pelicinus) [see Photo 6.] are the most successful outputs from this recent, well-executed program (Loi et al., 2005; Nichols et al., 2007). Yellow and pink serradella are the only species that are well-adapted to the sandy soils of coastal WA. New cultivars of yellow serradella (cvs. Yelbini, Charano, Santorini and King) and French serradella (cvs. Cadiz, Margurita [Photo 6], Erica) were selected for the combination of pod retention and straight (non-segmenting) pods, which allowed direct heading and reduced the need for seed processing. Gland clover (cv. Prima) has resistance to redlegged earth mite and aphids. Biserrula, which can be harvested with commercial headers, is a successful alternative to subterranean clover, which is difficult to harvest. Biserrula (cvs. Casbah, Mauro) offers a high level of hard seeds with a delayed seed softening pattern, a deep-rooted habit and a potential for herbicide-free weed management (Loi et al., 2005). Another legume species that is of particular interest is eastern star clover (Trifolium dasyurum) [Photo 6]. Following the normal break of season (late autumn), eastern star clover germinates several weeks after other pasture legumes and weeds (Loi et al., 2005), a pattern that can be combined with strategic grazing or herbicide application to control crop weeds during the pasture phase. In addition to the recent release of cultivars of these and other new annual legume species (e.g. T. spumosum , bladder clover), new cultivars have also revitalised the use of traditional subterranean clover and annual medic as well as less popular species such as rose clover (T. hirtum) and arrowleaf clover (T. vesiculosum) (Nichols et al. 2007). This program is a further example that illustrates Australian ingenuity in assembling temperate germplasm, ingenuity that also applies to the domestication of a range of genera and species for subtropical and tropical Australia (Section 5.3).
5.3 Sown pasture species, subtropical and tropical Australia 5.3.1 Pasture zones in the subtropics and tropics An expanded range of subtropical and tropical pasture species for use around the world has come from a sustained effort to collect, introduce and manage species for subtropical and tropical pastures in Australia. This effort was mounted during most of the 20th century by the Commonwealth Scientific and Industrial Research Organisation (CSIRO and its antecedent CSIR, initially through the Division of Tropical Pastures and subsequently the Division of Tropical Crops and Pastures), along with three State/Territory Departments of Agriculture (now NSW Industry & Investment; Queensland Primary Industries and Fisheries in the Department of Employment, Economic Development and Innovation, and the Northern Territory Department of Regional Development, Primary Industry, Fisheries and Resources). Eyles et al. (1985) and ‘t Mannetje (2003) outlined the history of this effort, including a pioneering phase up to 1952, a growth spurt towards the creation of a separate CSIRO Division of Tropical Pastures (1959) and a productive period into the 1980s. Although research activity peaked in the 1970s, work has continued on a range of pasture research issues, expanding and characterising tropical pasture resources (e.g., Cook et al., 2005). Directly and indirectly, the Australian work has assisted the development of pastures in a range of tropical countries (e.g. China, Liu et al., 2009; Uruguay, Real et al., 2005). Early successful introductions were Rhodes grass, Kikuyu, lucerne, white clover and various annual forages. As well, experience was gained with a range of tropical grasses and legumes, but pasture improvement was limited until the complex major and trace element deficiencies of the coastal soils were sorted out and corrected during the 1950s. Then, it was clear that certain trailing/climbing legumes, such as centro (Centrosema molle) and puero (Pueraria phaseoloides) in the north, and Desmodium spp., Macroptilium spp. and glycine (Neonotonia wightii) in the south, grew well once their rhizobiology limitations were resolved. Several grass species, belonging to genera including Digitaria, Panicum, Setaria and Paspalum, which were productive and persistent in plots, were adopted commercially. At this time (1960s-70s), constraints to research funding and the declining importance of dairying relative to beef production shifted the emphasis to tropical pastures further north and west of south-eastern Queensland. Concurrently, the emphasis in the main program shifted from species agronomy to pasture utilisation by cattle. It was realised that the impressive growth of tropical species that were tall (grasses) and/or climbing/twining (e.g. legumes such as siratro, Macroptilium atropurpureum) did not necessarily translate well into cattle production. The poorer production from pastures based on tall or climbing species versus shorter, denser pastures occurred both at low stocking rates, where the open sward structure resulted in cattle grazing for relatively long periods to harvest sufficient forage to meet their requirements (Stobbs, 1973), and at moderate to high stocking rates, where twining species persisted poorly under heavy cattle grazing (Jones and Jones, 1978). Hence, subsequent emphasis was on expanding the list of shorter, denser species that were likely to be tolerant of heavy grazing (Cameron et al., 1989), on improving disease and insect tolerance in proven species (Cameron et al., 1993 quoted by ‘t Mannetje, 2003), and overcoming anti-nutritional constraints to cattle production (Jones and Megarrity, 1986). Some of the persistent legumes released were lotononis, jointvetch (Aeschynomene americana, A. falcata and A. villosa) and creeping vigna (Vigna parkeri). The highly persistent and productive, rhizomatous legume Arachis glabrata was released as an option for intensively grazed dairy pastures, but it proved commercially unacceptable since it required vegetative propagation. Pinto peanut (A. pintoi) is now recommended widely. Relatively recently, forage resources in the form of a forage selection tool (SoFT) supplemented with fact sheets in CD-ROM (world database) and online (Australian database) versions have been made available (Cook et al., 2005 – see www.tropicalforages.info). Examples of the output of potentially suitable tropical species from the CD-ROM database are given in Table 6, for perennial grasses and legumes that tolerate heavy grazing on relatively dry sites (500-750 mm annual rainfall) and wet sites (1800-2500 mm). The species that are suitable for intermediate rainfall (800-1500 mm) areas can be inferred from this table. [Details of grass and legume species, with photographs, are also available in the FAO Grassland Species database < /www.fao.org/ag/AGP/AGPC/doc/GBASE/Default.htm >]. In Figure 12 are shown five pasture zones that occur in subtropical and tropical Australia – the subtropical transition zone, the humid coastal perennial pasture zone that is primarily confined to Queensland, the tropical (speargrass) pasture zone in Queensland that was originally colonised by Townsville stylo (Stylosanthes humulis), the wet/dry tropics of northern Australia and an inland, low-moderate rainfall zone (here termed tropical sub-humid/semi-arid perennial pasture zone) in which species must tolerate a long (6+ months) winter drought. These zones, described below, are a convenient simplification of reality. For greater detail concerning tropical pasture species recommended for regions in northern Australia, the reader is referred to the following on-line pasture database: www.tropicalgrasslands.asn.au/pastures/default.htm Recommendations covering pasture species for all Australian pasture locations, temperate and tropical, can now be found at an interactive website www.pasturepicker.com.au. 5.3.2 Subtropical transition zone In this coastal zone, which extends either side of the Queensland-NSW border from Maryborough (N) to Taree (S), systematic work to import and evaluate both temperate and subtropical species for coastal dairy pastures dates back to the 1890s, when paspalum (Paspalum dilatatum) was introduced and adopted enthusiastically. In this zone, temperate annuals/biennials (ryegrass, oats, annual clovers) are often sown as seasonal forages, while perennial ryegrass (or tall fescue), white clover, paspalum and Kikuyu are components of permanent pastures. A system is developing wherein base tropical pastures of pinto peanut or Kikuyu (weakened by glyphosate) are oversown with cool season annuals in March/April. For well-drained sites that are grazed leniently to moderately, other tropical species that are recommended include green and Gatton panics (Panicum maximum), glycine and siratro. On less well-drained soils with moderate to intensive grazing, the grasses pangola (Digitaria eriantha), setaria (Setaria sphacelata) and paspalum, and the legumes pinto peanut and creeping vigna, are sown. Creeping vigna is one of the few tropical legumes that is best under intensive grazing and it can combine successfully with competitive species such as Kikuyu and setaria. This zone strictly could include the tropical upland areas of the Eungella Plateau west of Mackay and Atherton Tableland near Cairns but these are not shown in Figure 12. Table 6. Sown pasture plants suitable for long-term pastures and heavy grazing in Australia’s subtropics and tropics (Cook et al., 2005).
In practice, a long list of grasses and legumes is recommended for the humid tropics of Queensland where there are extremes in latitude, soil fertility and landscape (from hilly to flood-susceptible flats). In the northern part of the zone (former rainforest), the most popular grasses, which may be sown without a legume, are signal grass (Brachiaria decumbens) and guinea grass (Panicum maximum = Megathyrsus maximus) but nitrogen fertilizer is required for maintenance and production. Guinea grass combines well with centro, puero or hetero (Desmodium heterophyllum) in less intensively managed pastures, and signal grass with pinto peanut in intensive pastures. In the central parts of this zone, Kazungula setaria, tall finger grass (Digitaria milanjiana), pangola grass and Rhodes grass are sown with American jointvetch, hairy jointvetch, siratro or centro. If the soil fertility is relatively low and the grazing system is intensive, Indian bluegrass (Bothriochloa pertusa), creeping bluegrass (Bothriochloa insculpta), Caribbean stylo (Stylosanthes hamata) and shrubby stylo (Stylosanthes scabra) are preferred. Several grasses are suitable for seasonally wet areas in this zone, such as para grass (Brachiaria mutica = Urochloa mutica), aleman grass (Echinochloa polystachya) and humidicola (Brachiaria humidicola = Urochloa humidicola). 5.3.4 Tropical (speargrass) pasture zone A notable early introduction into this perennial/annual zone was the free-seeding annual Stylosanthes humilis, Townsville stylo. This accidental introduction, which came into the country at the turn of the 20th century, was spread along the network of stock routes in north-eastern Queensland and northern Australia by animals and stockmen. According to Gillard and Fisher (1978), it was best adapted to land between the 800 and 1200 mm annual rainfall isohyets on most soils except saline coastal soils and heavy cracking clays. Townsville stylo could survive on soils of low fertility but it responded well to phosphatic fertilizers. It was compatible with the native speargrass. While it was often sown with setaria, it fixed insufficient N to maintain the vigour of that grass. Unfortunately, Townsville stylo succumbed to the disease anthracnose caused by Colletotrichum gloeosporioides (Davis et al., 1987) in the 1970s, by which time a number of alternative Stylosanthes species, hybrids and cultivars had been released or were in the pipeline. The Townsville stylo alternatives that are currently popular include shrubby stylo, caatinga stylo (Stylosanthes seabrana), Caribbean stylo and fine stem stylo (Stylosanthes guianensis var. intermedia). While stylos are sometimes used in sown pasture mixtures with less competitive grasses such as sabi grass (Urochloa mosambicensis), their main application is in native pasture amelioration. They are oversown into grassy woodland with minimal intervention, sometimes only after fire or tyne ripping. Walker and Weston (1990) mentioned the replacement of black speargrass with volunteer Indian bluegrass on 0.8 M ha in parts of coastal and sub-coastal north Queensland, as a result of heavy grazing that followed the anthracnose-induced collapse of the Townsville stylo component. When the stylo population “crashed”, leading to near denudation of catchments, the already naturalised Indian bluegrass was fortuitously able to revegetate the bare landscapes, thereby minimising the potentially catastrophic erosion problems that would have otherwise occurred. The current species that are suitable for sowing on sites in this zone include:
A successful coloniser in this zone has been Cloncurry buffel grass (Cenchrus pennisetiformis), which occurs widely in the watershed around the bottom of the Gulf of Carpentaria in north-western Queensland – an area of 1.2 M ha was involved by the late 1980s (Walker and Weston, 1990). According to Bortolussi et al. (2005c), sown grasses include birdwood grass (Cenchrus setigerus), buffel grass, para grass, Rhodes grass and sabi grass; sown legumes include Caribbean stylo, American jointvetch, shrubby stylo and roundleaf cassia. However, there have been few large-scale pasture sowings in the wet/dry tropics of northern Australia (Figure 8). Part of this lack is related to the monsoonal nature (wet summers, dry winters) of the local climate. Local farmers have adopted a cautious approach of trialling new species and mixtures, initially on a small scale. However, there are other important factors operating, such as the traditionally extensive nature of cattle production in northern WA and ‘the Territory’, the allocation of tracts of land as homelands for Aboriginal people, mining leases, defence areas and national reserves/parks. Some potentially useful species for permanent pastures in seasonally flooded areas in the monsoonal Northern Territory include Brazilian centro (Centrosema brasilianum), aleman grass (which can only be established from cuttings), green/Gatton panic and perennial forage sorghum (sorghum hybrid). Shrubby stylo is worth introducing into grassy pastures in inland, drier areas. Centrosema pascuorum is an important legume on the floodplain country and Digitaria milanjiana is also finding application. Andropogon gayanus and the water grass, Hymenachne amplexicaulis, which are very useful forages in their respective habitats, have both become environmental weeds in the region. 5.3.6 Tropical sub-humid/semi-arid zone This zone takes in the subhumid and semiarid agro-ecological zones (Figure 7). Mitchell grass, a prized native grass, grows well on extensive areas of vertosols (Figure 4) in this zone. Sown grass pastures, principally buffel grass, Rhodes grass, purple pigeon grass and bambatsi panic (Panicum coloratum), occur at sites in central and southern Queensland on the fertile brigalow clay soils and gidgee clay loams; the latter two grasses are suitable for seasonally flooded sites in the ‘channel’ (watercourse) country. About 70% of these sown pastures, the most extensive in area in Queensland, were sown to grasses without legumes. These grasses depend on the relatively high N status of the former acacia (legume) shrublands for production but this status and grass productivity are declining. It is hoped that Caatinga stylo, desmanthus and leucaena, recommended as legumes for this zone, will arrest or reverse these declines. On the plains of this zone, there are each year 1-2 M ha of winter and summer crops in northern NSW and southern/central Queensland, principally wheat and sorghum. The cropped areas are grazed after harvest. There has been work done to develop legumes that may be used either in short pasture phases of tropical cropping systems or as a component of a perennial pasture for areas where grazing intensity can be controlled (Cameron, 1996). This legume research was a response to declining grain yields and grain protein levels of cereal crops. Butterfly pea (Clitoria ternatea), burgundy bean (Macroptilium bracteatum) and lab lab (Lablab purpureus) are recommended as ley legumes in central Queensland, and burgundy bean has potential in southern Queensland also (Pengelly and Conway, 2000). Currently, about 1.2 M ha of lucerne pastures are grown to restore soil fertility after several years of cereal crops. These lucerne pastures also are grazed or cut for hay. According to Walker and Weston (1990), annual medics are naturalised on about 1.7 M ha of inland pastures and dry watercourses in southern Queensland. The interface between the temperate and subtropical areas that are either side of the inland NSW-Queensland border poses particular problems for pasture systems, requiring the selection and utilisation of temperate grasses that are either deep-rooted or summer dormant, or subtropical species that are frost tolerant (Boschma et al., 2009). 6. OPPORTUNITIES FOR IMPROVEMENT OF PASTURE RESOURCES 6.1 Research outcomes In Australia, as in many countries, the emphasis of research into pastures and grazing has evolved from a singular focus on factors limiting production to one that encompasses the effect of practices on environmental parameters such as soil pH (Box 1), soil erosion, nitrate leaching, pollution of groundwater by nutrients and chemicals, and the absorption/release of greenhouse gases. Often, broader systemic dimensions are considered, such as the impact of management practices and systems on the changes in the financial capital, social capital and even the political aspects of pasture/animal systems (Kemp and Michalk, 2007). This evolution is a follow-on to ideas on sustainable development espoused by authors such as Gordon Conway (productivity, stability, sustainability and equity – Conway, 1986) and Jules Pretty (external costs of agriculture – Pretty et al., 2000). A recent Australian example of this broad approach was the Sustainable Grazing Systems (SGS) program, which operated across the high rainfall zone (>600 mm/year) of southern Australia (Mason et al., 2003). The SGS program involved researchers and producers working together (the participative approach) in a program that explored natural capital (environmental issues), financial capital (the impact of grazing management or stocking rate on profit and risk) and social capital (adoption, personal growth and satisfaction, networking). In the program, there was a major focus on grazing management. This focus did not resolve the benefits or otherwise of different grazing methods on animal production and sustainability but benefits flowed from the co-learning component of the project, thereby contributing to the producers’ understanding of their grazing systems [Photo 9]. Similar participative approaches have been successfully used in subsequent programs that have explored the management of pasture systems to reduce salinisation in agricultural landscapes (Masters et al., 2006) and the integration of grazing and grain systems (Hacker et al., 2009). A broad approach is now being taken by most of the agencies that are helping Australian farmers adjust to the impact of climate change.
In recent years, the research agenda has broadened to include environmental, financial and social issues on the farm (Mason et al., 2003). Unfortunately, past research into on-farm business management and off-farm supply chains has often not been relevant to farm profits (McCown and Parton, 2006) and, while the need for social indicators in agriculture is acknowledged, there are as yet no agreed protocols for the routine collection of indicators that define the social capital of farm families. From the research and development pool of knowledge accumulated so far, there are a number of aspects of pasture management that are now part of industry best practice in Australia. An example is the widespread use of soil and plant tissue testing services in order to plan fertilizer applications, especially for the major nutrients P and S (soil tests) and trace elements (tissue tests) which are needed by legumes. These aspects are discussed further below. 6.2 Pasture management for productivity and sustainability 6.2.1 Fertilizer rates With the dependence on legumes, nitrogen fertilizer applications to sheep and beef cattle pastures are relatively uncommon in Australia. Hence, the emphasis is on the selection of an appropriate legume, the introduction of appropriate rhizobia (species- or cultivar-specific if needed), the application of fertilizers to correct major and minor element deficiencies that limit the growth of legumes and monitoring soil pH (Box 1).
6.2.2 Grazing management There are several principles relevant to grazing management systems in Australian systems and world agriculture. In spite of frequent advocacy, the majority of studies on temperate and tropical pastures indicate no advantage in animal production from rotational grazing systems compared to continuous grazing (Humphreys, 1997). However, there are some exceptions to this general rule:
6.2.3 Weed management Australia has a thorough system of screening and quarantining plants before they are allowed into Australia. The Future Farm Industries CRC (one of a network of Australian Cooperative Research Centres) has developed an ‘environmental weed risk protocol’ that is available on their website (http://www.futurefarmcrc.com.au). There is an Australian Weeds Strategy at www.weeds.gov.au/publications/strategies/pubs/weed-strategy.pdf, which defines the roles and responsibilities of the Australian government, the governments of States and Territories, local government and individuals in the management of weeds. Following the development of weeds that are resistant to herbicides, integrated weed management strategies are advocated, especially in mixed farming areas (Sindell, 2000). 6.3 Future opportunities 6.3.1 Research capacity (also see Section 7.) A constructive critique of the agricultural R&D system in Australia was made by Hamblin (2004). She acknowledged progress in terms of production research, but was less positive about the levels of investment into or benefits from research into issues of ecological sustainability, innovation beyond the farm gate (processing, distribution, promotion) or improving the budget sheet of farms and the well-being of rural communities. In recent years, these issues continue to provide a challenge for research institutions and funders. So too do shifts in the policies of governments who, noting the decline in the proportion (2.5%) of gross national product contributed by agriculture, lower receipts from production levies due to ongoing droughts and the declines in sheep and dairy cattle numbers, are spending less on agricultural research. Government departments, bureaus and universities also are offering contract rather than tenured employment to scientists and other professional researchers. These trends may limit future gains from agricultural research in Australia. More optimistically, the negative trends could be balanced by better communication between scientists around the world and by improved collaboration between production scientists and environmental scientists. Another issue, the slow adoption of research findings, especially complex technologies that are aligned with sustainable production, is being addressed through the adoption by the livestock industries of participatory extension methodologies (e.g. Pannell et al., 2006; Friend et al., 2009; Hacker et al., 2009) rather than employing the diffusion (trickle down) approach that is effective with simple technologies. 6.3.2 Molecular biology applications for pasture species improvement Spangenberg et al. (2001) outlined a number of opportunities and approaches for the application of transgenic and genomic technologies for the improvement of forage plants. Examples were given on how the genes controlling metabolic pathways might be manipulated to enhance forage quality, transgenic approaches to enhancing resistance to diseases and pests, the deconstruction and reconstruction of plant development, and the use of molecular markers. Biotechnology is justifiable on the basis that it has the potential to achieve what conventional plant breeding might never achieve. However, there are two issues that are likely to ensure that most of the ideas for projects may fail to produce an outcome. First, the pathway from the cell to the ecosystem level is difficult (Giampietro, 1994). The scientific understanding of the plant genome is still poor – substantial effort will be needed to assign function to genes, particularly when protein function is context dependent. There is a complex sequence of steps necessary to insert a gene, alter its level of expression and utilize it (Oram and Lodge, 2003). Biotechnologists have a track record of unrealistic optimism in terms of achieving, on-time and on-budget, the targets that they or their backers have set (e.g. the search for a bloat-resistant lucerne). Second, there is the matter of unintended consequences. The experience of Dear et al. (2003) with transgenic subterranean clover is revealing. A gene for tolerance to bromoxynil herbicide (bxn) was isolated from a soil bacterium and inserted successfully into a range of agricultural plants, among them subterranean clover. Dear and his colleagues explored some of the potential changes that a random insertion of the bxn gene might cause. The inclusion of the bxn gene did not change the agronomic characteristics of one of the three resultant lines, but the gene or transformation process did have unintended effects (reduced seed production, lower levels of hard seed, and changes to the levels of phyto-oestrogens) on the other two transgenic lines. Third, the ongoing, unresolved conflict about GM organisms is another negative complication. However, there are some Australian plant breeding groups, working with a major species for the world market (e.g. lucerne, cotton), that possess sufficient expertise and experience for success at the genome, plant and industry levels. Such groups will utilize molecular marker technologies that are useful in exploring plant genomes and in building up genetic combinations for heterosis and disease resistance (Irwin et al., 2001). 6.3.3 Pasture monitoring and decision support systems Pasture monitoring protocols such as PROGRAZE (Bell and Allan, 2000) and pasture-livestock models such as GrassGro (Clark et al., 2000) and DairyMod (Johnson et al., 2007) have been assembled and used to monitor progress and set targets in Australian pasture-livestock enterprises. Simple pasture-monitoring tools have been tested (Wolfe et al., 2006) to collect basic information on pasture parameters such as cover (%), botanical composition (%), biomass (kg/ha), growth (kg/ha.d) and plant populations (numbers/m2). However, there is as yet no complete and accepted protocol for pasture management on farms, and acceptance of an agreed industry protocol is an important industry need. It could be used to predict and monitor pasture production, environmental parameters and systemic stress. Individual parameters such as botanical composition are useful to assess pastures in terms of the risk of metabolic disorders (grass tetany, bloat) or the benefits likely from procedures such as winter-cleaning, which is the removal of grasses from pastures before the cropping phase to overcome cereal root pathogens and/or boost nitrogen supply. When linked to weather forecasting models, modelling could improve tactical and strategic decision-making, such as predicting periods that are favourable for destocking and restocking at the farm and regional levels. 6.3.5 The impact of global factors on pasture and livestock production in Australia In a global economy, there are several influences that will determine the capacity of Australia to grow pastures and produce livestock. On the demand side is world population and the increasing numbers of relatively affluent consumers, factors that will positively affect the global market for red meat. On the supply side are potentially negative impacts such as the political environment, climate change, and the availability of essential agricultural inputs such as fertilizer, chemicals and energy. Schiere et al. (2006) highlighted the importance of processes that interact rather than behave in a straightforward manner, such as the post-World War II boom in pasture improvement in Australia and economic reforms in China, that produced rapid rather than incremental advances or failures in agricultural systems. Future perturbations to world agriculture arising from climate change or fuel shortages may interact with agro-ecosystem types or government policies, and trigger major changes to agricultural industries. Australian agricultural producers, who receive mild benefits from government policies such as investment and research incentives, have so far adjusted to the realities of free markets. However, there are signs (increasing age of farmers, increasing indebtedness, difficulties in attracting skilled labour on farms) of market failure. One example is the plight of local dairy farmers who run large (250+ cow), multi-million dollar enterprises that do not produce a satisfactory return. Predictions of a hotter continent, a more erratic climate and a drier south-eastern Australia (McKeon et al., 2009) may bring greater operational diversity in Australian agriculture, at least at the regional level (Harle et al., 2007). Resource limitations and other constraints may encourage many livestock producers to seek a lower input, more ecologically-focused production system rather than one that operates at a higher level of production risk. Other graziers will respond to the expanded array of useful pasture species for tropical and temperate areas (Section 5); they will make greater use of perennial species, supplemented strategically with annuals, to convert rainfall to fodder and meat and to protect the soil resource. In the wheat belt, risky crop production areas may be turned over to meat and wool production (Kopke et al., 2008), while crops may extend further into suitable high-rainfall areas (Harle et al., 2007). Before the recent improvement in prices for livestock, extension officers acknowledged the social rather than technical difficulties of improving or expanding livestock production in the wheat belt, where many crop specialists reluctantly tolerate the presence of livestock (Robertson and Wimalasuriya, 2004) as a means of capturing some of the synergies of mixed farming. The strong demand for food may lead to a greater number of larger, specialised farms that achieve synergy through integration with complementary businesses. In Australia, the complexity of managing large, mixed farms may be offset through innovative business partnerships that not only retain mixed farming (diversification) but also encourage simultaneous specialisation, essentially by separating the management of crops and livestock and placing each enterprise into the hands of enthusiasts. For example, a well-organised sheep specialist could run flocks on several farms. Greater benefits may come from innovation in the economic and social aspects of agriculture, rather than by refining the technology of production. During the last two decades, while the Australian agribusiness sector has accepted a need to employ graduate agronomists to supplement the reduced advisory services provided by government, few agricultural specialists have been employed in commercial livestock production, either extensive or intensive. Hence, at least in Australia, there is an opportunity to overcome the lag in technology applied to grazing livestock production, technology that is behind the level applied to crop management or to intensive livestock. The need to manage greenhouse gas emissions, with livestock farms seen as part of the solution rather than as part of the problem (Howden and Reyenga, 1999; Howden et al., 2008), is another factor that may lead to an exciting future. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 7. RESEARCH AND DEVELOPMENT ORGANIZATIONS AND
PERSONNEL 7.1 The current landscape For the agricultural industries, Australia has pursued a strong policy of publicly-funded R&D, but private research investment has been relatively low. R&D support occurs in several forms. The Australian Government provides funding to CSIRO, the universities, the Australian Centre for International Agricultural Research, and Cooperative Research Centres that link several agricultural industries with public institutions and private companies. State Governments invest in their network of agricultural research centres and stations as well as into strategic partnerships. Finally there is a national system of Rural Industry Research Corporations (including Meat and Livestock Australia, Australian Wool International and the Grains Research and Development Corporation), which evolved from ad hoc industry funds. These corporations manage industry production levies that are matched with a $ for $ contribution from the Australian Government; increasingly, co-investment occurs with public and private entities. However, the overall investment into pasture research and development is declining. The main pasture/livestock research centres are located at Perth (WA); Katherine (NT); Townsville, Toowoomba and Brisbane (Qld); Armidale, Tamworth, Orange and Wagga Wagga (NSW); Canberra (ACT); Hamilton and Melbourne (Vic.); Hobart (Tas.); Adelaide (SA) (Figure 12). Pasture plant genetic resource centres are located in Biloela (Qld, tropical species), Adelaide (Medicago spp. and other legumes) and Perth (Trifolium spp. and other legumes). 7.2 List of selected personnel/organizations involved in pasture R&D
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9. CONTACTS AND ACKNOWLEDGMENTS
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Wednesday 9 October 2013
A comprehensive overview of Australian Agriculture
This site has a really excellent information about Australian Agriculture from a historical perspective. We have used some of the information for our cow Udder Brilliance's artwork. Thought we should share. http://www.fao.org/ag/agp/AGPC/doc/Counprof/Australia/australia.htm
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