Temporary cropping in semi-arid shrublands increases native perennial grasses

2011 ◽  
Vol 33 (1) ◽  
pp. 67 ◽  
Author(s):  
Y. Alemseged ◽  
R. B. Hacker ◽  
W. J. Smith ◽  
G. J. Melville
Keyword(s):  
Perennial Grass ◽  
Stable State ◽  
Ground Cover ◽  
Perennial Grasses ◽  
Grazing Management ◽  
Alternative Stable State ◽  
Pasture Production ◽  
Native Grasslands ◽  
Native Shrubs ◽  
Semi Arid

Thickening of native shrubs is a major problem in many ‘semi-arid woodlands’ as significant increase in shrub density is often negatively correlated with herbaceous vegetation and leads to reduced pasture production and soil erosion. This project aimed to test the hypothesis that temporary cropping (up to three crops in 15 years) consistently increases the density of native perennial grasses following the removal of shrubs. A total of 30 paddocks that had been cropped during the last 20 years were randomly selected using a satellite-based database that documented annual clearing and cropping history from 1987 to 2003. Paddocks were classified into four types based on clearing and cropping history and grazing management – not cleared (shrubs), regrowth (re-invaded by shrubs), set stocked (cropped and grazed), light/rotationally grazed (cropped and grazed). The responses of vegetation and soil (chemical and physical) properties to clearing and cropping were evaluated. Results indicated that ground cover, native perennial grass cover and standing dry matter were highest under light/rotationally grazed conditions. The shrub state represents a stable state within the Cobar pediplain brought about due to land-use change in the form of overgrazing and/or the removal of fire from the system. An alternative stable state was achieved as a result of disturbance in the form of clearing, cropping and grazing management thereby directly altering the shrub population. The resilience of this state is largely dependent on the grazing management system used and on the prevention of shrub from re-establishing while failure to control shrubs could lead to the re-emergence of the Shrub State. We conclude that native grasslands do regenerate following cropping after removal of shrubs. The importance of grazing management for restoring perennial ground cover following removal of shrubs and temporary cropping has been clearly demonstrated by the study.

Effects of nitrogen and phosphorus on vegetation dynamics of a degraded native grassland in semi-arid south-eastern Australia

2011 ◽  
Vol 33 (1) ◽  
pp. 87 ◽  
Author(s):  
R. B. Hacker ◽  
I. D. Toole ◽  
G. J. Melville
Keyword(s):  
Vegetation Dynamics ◽  
Plant Density ◽  
Perennial Grass ◽  
Ground Cover ◽  
Perennial Grasses ◽  
Grass Species ◽  
Nitrogen And Phosphorus ◽  
Mineral N ◽  
Eastern Australia ◽  
Semi Arid

The roles of nitrogen (N) and phosphorus (P) in controlling vegetation transitions in a degraded semi-arid grassland were investigated in a factorial experiment that combined two initial levels of perennial plant density (low and high), three levels of N (N+, N0 and N–) and two levels of P (P+ and P0). Increased levels of both N and P were achieved by fertiliser addition while sucrose was used to reduce the level of N. Vegetation dynamics were driven primarily by soil N rather than P. Addition of sucrose, which was inferred to result in the immobilisation of mineral N, reduced the growth of annual species and facilitated the establishment and growth of native perennial grasses. Addition of P generally had no significant effect on dry matter production, either in total or for species grouped as forbs, annual grasses and perennial grasses, or on recruitment and mortality of perennial grasses. However, at some times of observation addition of P increased ground cover and/or the basal circumference of some perennial grass species. Basal circumference for Enteropogon acicularis was also increased by addition of N. Soil biological activity, measured by decomposition of cotton strips, was increased by addition of N, which maintained vegetation in an annual-dominated condition, and was not affected by addition of P. Carbon addition has the potential to assist restoration of this grassland. However, the capacity of some native grass species to respond to increased fertility suggests that once restoration is achieved some increase in fertility may be beneficial for pastoral production.

Increased production and cover in a variable native pasture following intensive grazing management

2017 ◽  
Vol 57 (9) ◽  
pp. 1812 ◽  
Author(s):  
W. B. Badgery ◽  
G. D. Millar ◽  
K. Broadfoot ◽  
D. L. Michalk ◽  
P. Cranney ◽  
...  
Keyword(s):  
Native Species ◽  
Ground Cover ◽  
Perennial Grasses ◽  
Grazing Management ◽  
Landscape Position ◽  
Pasture Production ◽  
Native Pasture ◽  
High Production ◽  
Native Pastures ◽  
Production Zone

Native pastures account for approximately half the grazing area of the high-rainfall zone of southern Australia and the appropriate intensity of grazing management to improve pasture production and to sustain native species composition is still debated. This paper describes differences in pasture herbage mass, ground cover and composition for a native pasture managed under three distinct grazing-management intensities (1-, 4- and 20-paddock grazing systems). Grazing-management treatments were implemented for 4 years across a variable landscape and the interaction of grazing management and landscape position (high-, medium- and low-production zones) were examined. Increasing the intensity of grazing management (number of paddocks in the grazing system) resulted in higher standing, green and litter herbage mass and ground cover of pastures, with differences most pronounced in the high-production zone where selective grazing was regulated with grazing management. Landscape position largely influenced pasture composition, with higher pasture production and more productive species (e.g. Microlaena stipoides, Lolium rigidum and legumes) in the high-production zone. Small increases in the DM of native perennial grasses and lower levels of legumes and broad-leaf weeds developed in the 20-paddock system compared with grazing in 1- and 4-paddock systems. Net pasture growth was higher in the 20-paddock than 1-paddock treatment during spring in the last 2 years of the experiment, resulting in 21% (1.6 t DM/ha) more herbage mass accumulated over the year. While productivity and cover were higher under intensive rotational grazing, grazing management had little influence on pasture composition. A stable perennial pasture (>70% perennial grasses) stocking rates that were not degrading and the strong influence of landscape on pasture composition limited management influences. Practically, the results indicated that, at the same stocking rate, increasing the intensity of grazing management can increase the average pasture herbage mass, ground cover and pasture growth by more evenly distributing grazing.

Herbage mass thresholds rather than plant phenology are a more useful cue for grazing management decisions in the mid-north region of South Australia

2010 ◽  
Vol 32 (4) ◽  
pp. 379 ◽  
Author(s):  
Lewis P. Kahn ◽  
Judi M. Earl ◽  
Millie Nicholls
Keyword(s):  
Perennial Grass ◽  
South Australia ◽  
Plant Phenology ◽  
Perennial Grasses ◽  
Grazing Management ◽  
Plant Production ◽  
Sheep Grazing ◽  
Management Decisions ◽  
Basal Cover ◽  
Seasonal Grazing

Research was conducted in the mid-north of South Australia over the period 2000–05 to evaluate the effects of different grazing management cues on composition and production of a grassland. The management cues were based on calendar, plant phenology or herbage mass thresholds using grazing exclusion as a control. There were five grazing treatments: (i) regional practice (RP), where sheep grazed continuously for the period April–December; (ii) autumn rest, where sheep grazing was restricted to June–December; (iii) spring rest, where sheep grazing was restricted to April–August; (iv) high density and short duration (HDSD), where herbage mass thresholds determined when grazing occurred and for what duration; and (v) nil (NIL) grazing by domestic herbivores. Mean annual estimates of herbage mass were highest for NIL and HDSD and inclusion of the estimate of herbage consumption by sheep resulted in greatest primary plant production in HDSD. The contribution of perennial grasses to herbage mass declined with RP and seasonal grazing treatments. Frequency of perennial grasses was unaffected by grazing treatment but the number of perennial grass plants increased over time in RP and seasonal treatments. HDSD allowed maintenance of basal cover whereas bare ground increased with RP and seasonal treatments. Litter accumulated in NIL but this was associated with a decline in perennial basal cover. Seasonal grazing treatments did not provide an advantage over RP and there appeared to be no benefit from including phenology in management decisions. In contrast, HDSD resulted in a stable and productive grassland ecosystem, with stocking rate estimated at 78% greater than other treatments. These features offer a desirable mix for future industry adoption in the mid-north of South Australia.

Increasing the perennial grass component of native pastures through grazing management in the 400 - 600mm rainfall zone of central western NSW

2009 ◽  
Vol 31 (4) ◽  
pp. 369 ◽  
Author(s):  
A. M. Bowman ◽  
Y. Alemseged ◽  
G. J. Melville ◽  
W. J. Smith ◽  
F. Syrch
Keyword(s):  
Weed Control ◽  
Perennial Grass ◽  
Perennial Grasses ◽  
Grass Species ◽  
Native Grasslands ◽  
Key Species ◽  
Grazing Strategies ◽  
Native Pastures ◽  
Fertiliser Application ◽  
Broadleaf Species

Native grass-based pastures in the 400–600 mm rainfall zone of central NSW are an important basis for extensive grazing industries. However, over time they have been invaded by exotic weeds. This study aimed to evaluate several grazing strategies for the maintenance or improvement of native grasslands based on pasture productivity and species diversity. Seven grazing strategies, ranging from set stocking to permanently removing stock, were employed to evaluate the strategy that would best maintain a high proportion of desirable perennial grass species. Grazing treatments were evaluated based on their effects on pasture composition and on the density of selected key grass species such as Enteropogon acicularis (Lindl.) Lazar. (curly windmill grass). Managing the utilisation of the key desirable species E. acicularis combined with weed control was the most successful strategy in terms of increasing the density of the key species, although no treatment increased the proportion of desirable perennial grasses and desirable broadleaf species. This was followed by a ‘farmer’s choice’ strategy, which involved combining phosphorus fertiliser application, weed control and rest from grazing. In contrast, strategies that involved either a ‘summer lockup’ or ‘weed control’ alone performed poorly. It is concluded that native pastures in this region could be rehabilitated, and their productivity restored, by following strategies that provide rest from grazing, based on the utilisation levels of key, species combined with control of annual weeds.

The Influence of Recent Grazing Pressure and Landscape Position on Grass Recruitment in a Semi-Arid Woodland of Eastern Australia.

1996 ◽  
Vol 18 (1) ◽  
pp. 3 ◽  
Author(s):  
VJ Anderson ◽  
KC Hodgkinson ◽  
AC Grice
Keyword(s):  
Seedling Emergence ◽  
Perennial Grass ◽  
Soil Surface ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Run Off ◽  
Eastern Australia ◽  
Annual Grasses ◽  
History Of ◽  
Semi Arid

This study examined the effects of previous grazing pressure, position in the landscape and apparent seed trapping capability of soil surface micro-sites on recruitment of the perennial grass Monachather paradoxa (mulga oats) in a semi-arid woodland. Seedling emergence was counted on small plots which had been kept moist for one month. The plots were on bare ground, or at grass tussocks, or at log mounds, sited in the run-off, interception and run-on zones of paddocks that had been grazed for six years at 0.3 and 0.8 sheep equivalent/ha. Few naturally occurring perennial grass seedlings emerged on any of the sites. The level of previous grazing pressure influenced the recruitment of grasses from natural sources as well as from seed of M. paradoxa broadcast on the soil surface; significantly more grass seedlings recruited in paddocks stocked at 0.3 than at 0.8 sheep/ha. Emergence of the sown grass did not differ significantly between the three zones in the landscape, but trends in the data suggest the interception zone may have been the most favourable. Recruitment from in situ grass seed was highest in the mulga grove (run-on) zone. Most seedlings of the sown grass emerged around the bases of existing perennial grass tussocks, but recruitment of volunteer perennial and annual grasses was more evenly distributed between the mulga log-mounds and perennial grass tussocks. It is concluded that very low levels of readily germinable seed of perennial grasses remained in the soil at the end of the drought and that areas with a history of high grazing pressure have less probability of grass recruitment when suitable rain occurs.

Managing competitive interactions to promote regeneration of native perennial grasses in semi-arid south-eastern Australia

2017 ◽  
Vol 39 (1) ◽  
pp. 59
Author(s):  
Ronald B. Hacker ◽  
Ian D. Toole ◽  
Gavin J. Melville ◽  
Yohannes Alemseged ◽  
Warren J. Smith
Keyword(s):  
Weed Control ◽  
Biomass Production ◽  
Soil Nitrogen ◽  
Perennial Grass ◽  
Perennial Grasses ◽  
Soil Nitrate ◽  
Nitrogen Reduction ◽  
Eastern Australia ◽  
Semi Arid ◽  
Native Perennial Grass

Treatments to reduce available soil nitrogen and achieve specified levels of weed control were evaluated for their capacity to promote regeneration of native perennial grasses in a degraded semi-arid woodland in central-western New South Wales. Treatments were factorial combinations of nitrogen-reduction levels and weed-control levels. The four levels of nitrogen reduction were no intervention, and oversowing of an unfertilised summer crop, an unfertilised winter crop or an unfertilised perennial grass. The three weed-control levels were defined by the outcome sought rather than the chemical applied and were nil, control of annual legumes and control of all annual species (AA). Regeneration of perennial grasses, predominantly Enteropogon acicularis, was promoted most rapidly by the AA level of weed control with no introduction of sown species. Sown species negated the benefits of weed control and limited but did not prevent the regeneration of native perennials. Sown species also contributed substantially to biomass production, which was otherwise severely limited under the AA level of weed control, and they were effective in reducing soil nitrogen availability. Sown species in combination with appropriate herbicide use can therefore maintain or increase available forage in the short–medium term, permit a low rate of native perennial grass recruitment, and condition the system (by reducing soil mineral nitrogen) for more rapid regeneration of native perennials should annual sowings be discontinued or a sown grass fail to persist. Soil nitrate was reduced roughly in proportion to biomass production. High levels of soil nitrate did not inhibit native perennial grass regeneration when biomass was suppressed by AA weed control, and may be beneficial for pastoral production, but could also render sites more susceptible to future invasion of exotic annuals. The need for astute grazing management of the restored grassland is thus emphasised. This study was conducted on a site that supported a remnant population of perennial grasses. Use of the nitrogen-reduction techniques described may not be appropriate on sites where very few perennial grass plants remain.

Evaluation of native and introduced grasses for low-input pastures in temperate Australia: rationale and scope

2005 ◽  
Vol 27 (1) ◽  
pp. 1 ◽  
Author(s):  
R. D. B. Whalley ◽  
D. A. Friend ◽  
P. Sanford ◽  
M. L. Mitchell
Keyword(s):  
Arid Regions ◽  
Perennial Grass ◽  
Perennial Grasses ◽  
High Input ◽  
Low Input ◽  
Evaluation Phase ◽  
Site Evaluation ◽  
Broad Objective ◽  
Evaluation Project ◽  
Semi Arid

The historical approach to pasture improvement in the high rainfall zone of temperate Australia has been to add introduced herbaceous legumes and to replace perennial native grasses with introduced species requiring high inputs of fertiliser for maintenance. The application of this high-input approach on land with low capability has lead to the loss of perennial grasses, erosion, soil acidification and increasing salinity on the lower slopes. This model of pasture improvement has not been successful on the margins of the wheat belt and in semi-arid regions. The Native and Low-input Grasses Network (NLIGN) was established in 1996 to coordinate research on grasses suitable for land with low capability and for semi-arid regions. The NLIGN multi-site evaluation project was initiated to test promising lines (accessions) of native and introduced grasses for low-input pastures at eight sites across southern Australia. The broad objective of the project was to identify native and/or introduced perennial grass lines that had possible commercial potential for low-input pastures. This objective was achieved in an initial 3-year evaluation phase, which began in 1998 and tested lines for persistence, production and palatability.

Ground cover in temperate native perennial grass pastures. I. A comparison of four estimation methods

2002 ◽  
Vol 24 (2) ◽  
pp. 288 ◽  
Author(s):  
S. R. Murphy ◽  
G. M. Lodge
Keyword(s):  
Image Analysis ◽  
Digital Image ◽  
Digital Image Analysis ◽  
Perennial Grass ◽  
Canopy Cover ◽  
Ground Cover ◽  
Estimation Methods ◽  
Visual Estimation ◽  
Pasture Production ◽  
Point Quadrat

Studies were conducted to compare visual estimates of ground cover and canopy cover by both inexperienced and experienced observers and to compare those estimates with those from more objective methods in native pastures in the high rainfall, temperate rangelands of northern NSW. Ground cover and canopy cover of 60 quadrats was estimated using visual, mapped area, digital image analysis and photo point quadrat methods. Inexperienced observers were trained by estimating ground cover of reference quadrats. Differences between mean visual estimates of ground cover and canopy cover for experienced and inexperienced observers were not significant (P>0.05). Mean ground cover estimates by the mapped area, digital image analysis and point quadrat methods were also not different from each other. The overall relationship between mean visual estimate and mean objective estimate of ground cover was non-linear (second order polynomial, R2 = 0.93), observers tending to underestimate in the mid-range (20 to 80%) of cover compared with objective methods. Mean visual estimate of ground cover was 73.7% compared with the mean objective estimate of 83.7%. Visual estimates of canopy cover (mean 34.6%) were highly correlated (R2 = 0.90) with those of the mapped area method (mean 34.3%) and the relationship was linear. Measurement of ground cover is a standard technique used in many pasture ecology and management studies and is increasingly being used by land managers to monitor pasture production and sustainability. Inexperienced observers were trained quickly and easily to estimate ground cover and canopy cover with sufficient accuracy to identify ranges of cover using visual estimation, indicating that the visual estimation technique should be suitable for estimating ground cover in land management research.

Towards sustainable temperate perennial pastures

2000 ◽  
Vol 40 (2) ◽  
pp. 125 ◽  
Author(s):  
D. R. Kemp ◽  
P. M. Dowling
Keyword(s):  
Management Practices ◽  
Perennial Grass ◽  
Collaborative Study ◽  
South Australia ◽  
Acid Soils ◽  
Perennial Grasses ◽  
Grazing Management ◽  
Grass Species ◽  
Weed Invasion ◽  
Eastern Australia

Naturalised pastures across the higher rainfall (>600 mm) perennial pasture zone of south-eastern Australia are less productive than they were, while sown pastures fail to maintain their initial levels of production. Several factors have contributed to this, including lack of knowledge of suitable grazing practices, weed invasion, increasing acid soils, rising water tables and poor management practices during droughts. A key issue in each case is the decline in perennial grass species which is both a cause and effect of the decline in productivity and sustainability of these ecosystems. This paper introduces a volume devoted to the largest collaborative study done to evaluate tactics for better grazing management and to improve the sustainability of perennial pasture ecosystems. Grazing practices to manage the composition of pastures have been largely neglected in pasture research, but are an important first step in improving pasture sustainability. This paper also outlines a new, open communal grazing experimental design which was developed and used across 24 sites on farms in New South Wales, Victoria, Tasmania and South Australia, to evaluate tactics for grazing management. The general aim across these experiments was to maintain (if adequate) or enhance (if degraded), the proportion of desirable perennial grasses in the sward to achieve more sustainable pastures. The results will provide the basis for building more sustainable grazing systems.

Temperate Pasture Sustainability Key Program: an overview

2000 ◽  
Vol 40 (2) ◽  
pp. 121 ◽  
Author(s):  
W. K. Mason ◽  
G. Kay
Keyword(s):  
Perennial Grass ◽  
Perennial Grasses ◽  
Environmental Benefits ◽  
Grazing Management ◽  
Murray Darling Basin ◽  
Development Corporation ◽  
Management Guidance ◽  
Experimental Protocols ◽  
Grazing Systems ◽  
The Individual

This special edition of the Australian Journal of Experimental Agriculture presents papers from work undertaken as part of the Temperate Pasture Sustainability Key Program (TPSKP; see Fig. 1), and presented at a workshop in Sydney in November 1997. TPSKP was initiated by Meat and Livestock Australia (MLA). The Land and Water Resources Research and Development Corporation, the International Wool Secretariat and the Murray Darling Basin Commission were joint funders of some of the individual projects. Most projects were carried out on private properties, and many had producer groups associated with the sites to provide input into treatment selections as well as management guidance and support. This substantial producer input was provided free to the program. The success of TPSKP relied heavily on physical and financial support from State departments of agriculture and conservation, CSIRO and universities, and also on the enthusiasm of these groups to work collaboratively across the 4 south-eastern states. One of the key results of this cooperation was the development of a set of experimental protocols so that measurements taken anywhere in TPSKP could be directly compared. TPSKP aimed to develop the principles for manipulating pasture composition to make grazing systems more productive and sustainable. The program priorities were to: (i) determine by survey the attitudes of producers to grazing management and identify the characteristics of those producers most likely to adopt the program results; (ii) demonstrate by June 1996 that potentially responsive perennial grass-based pastures could be upgraded using grazing management to become a ‘desirable’ pasture for animal production and sustainability; (iii) demonstrate by June 1996 that newly sown perennial grass-based pastures could be maintained in a desirable condition using grazing management; (iv) determine the critical factors responsible for the capacity of perennial grasses to persist, respond to drought, and ameliorate land degradation; (v) develop producers’ skills in pasture species identification, pasture and animal assessment, and feed budgeting, both to enhance their existing management, and to ‘prime’ them for the outputs from TPSKP; (vi) to demonstrate (in phase 2) that improvements in pasture composition and grazing management can have both economic and environmental benefits.

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